Thursday, December 17, 2009

Seeing the Nissan Leaf in Person

Things have been nuts this week, but I did get a chance to see the Nissan Leaf come to Portland today. It arrived at OMSI this morning and the OEVA got a private session with the Leaf this afternoon.


Here's Nissan's spokesperson who graciously answered all our geeky questions about the car. The Leaf boasts a 100 mile range on a 24KW battery pack. I have a 14KW battery pack and I only get about 20 miles when going on the freeway. The 100-mile range of the Leaf is based on a profile called LA-4 which is mostly stop-n-go city driving around 25 MPH. Nissan did say that commuting on the freeway at 60mph would probably yield a range of 75-80 miles instead.


Here's the requisite photo op with the Leaf showing the charging plugs at the front of the car. The one on the left takes a 440V 50A input while the plug on the right takes the standard J1772 plug that the EV industry has been trying to settle on for years.

I'm still weighing in on giving up on my homebrew Civic-EV and just buying one a Leaf. I still have a few more months to decide.

Monday, December 14, 2009

When Things Fall Apart

Yesterday was not a good day. My landline and internet connection went dead on Saturday and the lamp globe for my ceiling fan broke apart above my bed, putting glass shards in the covers.

This gave me an excuse to get off my computer and drive over to Home Depot yesterday (Sunday) to try and find a new globe for the ceiling fan. I had recently installed the PakTrakr system, so I cleared out the serial logging attachment and started collecting data. On the way to Home Depot, I missed my exit and ended up going another two miles to the next exit. I knew I had gone farther than my battery pack should have handled, especially in the cold, so I stuck to city streets and slowly drove home.

Halfway home, the battery gave out. I crawled into a Taco Time and asked if I could plug in. The manager pointed me to an outlet outside the building but he didn't think it worked. It didn't. After that, I walked a block away and found an auto parts place that was kind enough to let me plug in. After the car sat for 20 minutes, I had enough juice to get to the auto parts place. I also collected the serial data log on my laptop from the PakTrakr for later analysis.

After plugging in, my friend Ruth picked me up and dropped me off at home. I had an appointment last night near the auto-parts place. My plan was this: have a friend drive me to pick up the Civic (after four hours of charging), drive to my appointment, plug in there for an additional three hours and hopefully have 40% charge left to get home.

We'll, I picked up the car from the auto-parts place, drove to my appointment and plugged in. Three hours later, I came out and realized that the charger hadn't given the batteries any extra charge. After poking around under the hood, I also found a critical resistor that enabled the DC-DC converter had broken off. Without the DC-DC converter to charge my 12V battery, my car would die quickly with the headlights on at night. It was rather moot because I still had little charge in my batteries. It looked like the charger had given up the ghost on me.

I got a ride home from another friend (it's good to have friends when you own a home hacked EV) and called a tow-truck this morning through BWC (the environmentally friendly alternative to AAA). I felt rather sunk all night because the car is basically useless without the charger and the batteries will degrade rather quickly if they sit in a discharged state.

I got the car home later this morning, fixed the resistor for the DC-DC converter and tried the charger again. To my surprise, the charger actually started up. My batteries seemed to be quite out of balance and the charger just wasn't putting much amps into the batteries, even with the shunts not active yet.

I still have to analyze the system more, but here's what I think is happening: The charger can only generate about 175 volts because it gets it's input voltage by rectifying the 120V AC line. When cold, AGM batteries need a much higher charging voltage. If I look at the datasheet for the LifeLine batteries, I actually need to charge each battery up to 14.90 volts at 40 degrees F to get to 80% charge. Let's see, 14.90V x 12 is 178.8V, which is higher than the charger can actually put out. The battery shunts were actually working properly and only shunting the batteries when they reached 14.9V. Since the charger couldn't reach that level for all batteries simultaneously, only a few shunts kicked in before the charge current dropped precipitously, leaving an unbalanced pack.

In short, It doesn't look like the Belktronix charger can actually charge these particular AGM batteries under cold temperatures properly.

My next task was to look at some of the PakTrakr data I gathered. The serial log was heavily garbled, so I couldn't just load it into a spreadsheet. I had similar noise issues with the 914EV here, but adding a 100 ohm series resistor didn't clean up the issues.

I did find that under massive current draws that at least one battery was getting yanked down to 7.2 volts (ouch!). Either that battery is undercharged or I perhaps hurt it over this past year and it's (probably) damaged. It's too bad that the best battery data comes under a high current draw when the serial data is the noisiest.

This being the wintertime, it'll probably be a few months before things heat up to where I can effectively drive the car again. In the meantime I'm going to check out Nissan's Leaf this week and think about ditching all this unreliable homebrew stuff to buy a commercially engineered EV...

Happy Holidays!
Tim

Sunday, December 6, 2009

Replacing and Saving the Aux Battery

Well, the car's back on the road again. Yay! I replaced the 12V auxiliary battery (a group 30 motorcycle battery) and got a 2 year warranty on it just in case.

I remember in the past, I fully drained my 12V accessory battery at least twice by accidentally leaving the headlights on. In fact, I almost did it again yesterday when driving the car over to a friend's place. The car is a bit older and doesn't have an alarm when you leave the headlights on when turning off the ignition.

To prevent leaving on the Civic headlights, I installed a piezoelectric buzzer from Radio Shack with an inline diode.


Here is the buzzer with two fast-on connectors and the inline diode with the positive (red) buzzer lead. The anode of the diode is crimped to the fast-on connector and the cathode is crimped to the positive lead with a red crimp jumper. I probably could have soldered this and added heatshrink tubing, but this was faster.

The reason for the diode is that I only want the buzzer to be on when the headlights are on and the ignition is off. In the event that the headlights are off and the ignition is on, I don't want any current flowing backwards through the buzzer, possibly damaging it.


Here is the buzzer installed to the testpoints on the fuse block. I had already figured out this fuse block in an earlier post, so I knew which ones to tap into. The tachometer is gone, so I can tap into the fuse block where the tach light input was connected.

The second testpoint from the right goes to 12V when you turn on the parking lights or headlights. That gets connected to the positive buzzer wire through the diode. The third testpoint from the right is the ignition signal which goes to 12V when the key is on. The buzzer only activates when the ignition key is off and the parking/headlights are on.

I hope this saves me a lot of headaches with the new auxiliary battery. With temperatures dropping quickly, I don't know if I can get to work, but at least I can cruise around town with a heavy sweater on. (still no heater in this machine... :)

Happy Holidays,
Tim

Saturday, December 5, 2009

Comparing Conversion Costs with Paul

Paul Pancella (see link at right) put together a great spreadsheet comparing his Civic conversion costs with mine. There are a few minor updates, but things are very close for the most part. The only things that have changed on the Open Source Civic are the MES vacuum pump for the brakes and the fact that I ditched the custom tachometer and pillar pod. Even with these differences, the prices only change about $100.

Thanks for assembling this list, Paul!

Tim

(click on the picture below to get a full size version)

Hints from Paul on Paktrakr Installation

I'm just cleaning up my e-mail this morning and found a message from Paul Pancella about more installation issues regarding the PakTrakr system:

I can share my experience with the PakTrakr if you want. Ken Hall was very helpful, but the device itself was a little disappointing. The main thing is to be very careful with installation. The directions mention it, but it can't be emphasized enough, the remotes are easily destroyed if the ring terminals contact any battery terminals out of sequence. Depending on your physical setup, this can be hard to avoid during installation, since long wires are provided for each input. I'd recommend taping over all the ring terminals except the black one before getting near the car, then untaping individually as you install.

The temperature data from the remotes can be very useful, but the calibration on my units is at least 10 F degrees off. This was on my list of complaints when I twice sent the units back to Ken, but he was either unable or unwilling to do anything about it.

The individual module voltages are reported to 0.1 V precision, but again at least in my case, a few channels have offsets larger than this (up to 0.4 V). This magnitude is obviously significant in terms of balancing, so you will want to check every channel against a meter after installation. The offsets appear to be stable, so they can be accounted for if known.

I assume you will still have the Link-10? The PakTrakr has a "fuel gauge" function, but I'd guess the one on the Link-10 is a lot better. It will be interesting to compare them. I think mine is not very useful, maybe in part because it gets fooled by big voltage swings with regen. The whole system probably works better with lead acid than NiMH anyway.


I just wanted to pass this information along to all of you.

Cheers,
Tim

Tuesday, December 1, 2009

Installing the PakTrakr, Dead Aux Battery

Hi All,

The Civic-EV blog has been slow due to my bad batteries and being swamped at work. I got the recalibrated PakTrakr back a few weeks ago and finally had some time to install it tonight.

I've heard of some other folks blowing up their PakTrakr modules, so I tried a few tricks that seemed to work quite well in preventing spurious voltage spikes from killing the modules.

First of all, I needed to install two modules with six batteries apiece, so I split the battery pack into two halves. This does two things: it makes sure there is no current flowing in the cables and it isolates the two halves so that the PakTrakr modules don't see large voltage spikes when removing cables from the battery terminals.

Second, I put all the PakTrakr terminal loops in a plastic bag and only pulled one out at a time. This prevented the loops in the plastic bag from touching anything like the chassis or a battery terminal that could have provided a significantly higher/lower voltage.

Third, I installed each PakTrakr terminal loop from the lowest voltage up to the highest voltage and tightened the battery terminal at each step. This insured that each block of six batteries didn't get split up and introduce wide voltage variation.

The last trick involved connecting the two halves of the pack back together. Since I had to re-install a high current cable onto the battery lug, I removed the PakTrakr terminal first, touched the high-current cable to the battery lug (not to the Paktrakr terminal!) and then attached the PakTrakr terminal with a screw to the fully connected setup. Again, the intent of this was to prevent large voltage differences from blowing up the PakTrakr.

On a sadder note, I must have had a large leak in the system or a bad accessory battery, because it measured 2.9 volts after sitting in the car for a few weeks. This battery has probably been bad for awhile because one of the cells was bulged out, perhaps from the DC-DC converter dumping 40 amps into it. After some wrestling, I wiggled it out and will get a new one by the end of the week.

With the PakTrakr installed, I now have a good tool for seeing which batteries are dying first. Since I ran the car on a rather empty and unbalanced pack, I suspect I killed a battery or two. All batteries are at a nice 13.0-13.1 volts at full charge, but I suspect that some have significant loss in their capacity. We'll see...

Friday, October 30, 2009

John's PakTrakr Display

I shipped the PakTrakr modules back to the owner (Ken Hall) for calibration. Ken mentioned that they were rebuilding their calibration unit and would send the modules back as soon as it was finished.

I also received an e-mail from John Barton who used the open-source Civic battery rack design as a starting point for his own lithium-ion battery racks for his Civic DelSol:

Hi Tim,

I'm finishing up my second ev conversion, this time its a '93 Honda del Sol. My blog is http://mt-ev.blogspot.com. I'm also finishing a display for the paktrakr that runs on windows ce 5.0. I've got a basic version running on a GPS. Since you are using a paktrakr I thought you might like to give the display I wrote a try. Let me know if you are interested and I can send you an early version of the bits. I'll be blogging about it in a day or so.

The display I'm using is this:
http://www.dealextreme.com/details.dx/sku.22067

Also it requires a serial to bluetooth adapter like the IOGEAR.

Regards,
John Barton
It looks like he has a cool display that takes the PakTrakr output and shows in a user friendly format. I'm quite swamped these days, so I'll consider trying it out if things slow down this winter.

Looking forward to getting my PakTrakr back...


Friday, October 16, 2009

Installing the PakTrakr

I took some time to install the PakTrakr modules today. I was a bit disappointed in the voltage measurements from the PakTrakr remotes, so I'll probably send them back for recalibration. Here are the voltages I measured:

Unit #1






Battery # Battery(V) PakTrakr(V) Difference(mV)
1 13.43 13.5 70
2 13.49 13.7 210
3 13.48 13.4 -80
4 13.49 13.9 410
5 13.52 13.9 380
6 13.28 12.9 -380




Unit #2






Battery # Battery(V) PakTrakr(V) Difference(mV)
1 13.41 13.5 90
2 13.46 13.7 240
3 13.47 13.4 -70
4 13.46 13.7 240
5 13.5 13.7 200
6 13.29 13.5 210

Unit #2 isn't too far off, but batteries 4, 5 and 6 on unit #1 have too much error to accurately determine the state of the pack. I contacted Ken Hall at PakTrakr today for advice before I send the units back.

To help with air resistance, I might run to the plastics store and cover the entire front grille with a sheet of ABS plastic to see if that cuts down on the drag as well as the cooling effect on the front batteries...

Saturday, October 3, 2009

Range Anxiety

As you've probably noticed, things have been a bit quiet here. The new vacuum pump is working well and is nicely quiet.

As the temperatures drop, the capacity of my batteries drop as well. After almost a year of hard driving, I suspect the batteries are also losing capacity. Over the past week, I've been driving a gas car because I had long errands after work that would have exceeded the maximum range of the Civic-EV. The few times I did go into work, I ended up crawling along at five miles an hour for the last half-mile.

If I force myself to stay under 55 miles an hour at all times and use hypermiling techniques as much as possible, I don't lose power near the end of my commute, but as temperatures drop, I fear that I won't even be able to even get to work.

This is the classic problem with electric vehicles: range anxiety. I have plenty of power from the Warp9 motor, but the battery current and capacity just isn't enough for my commute anymore. I can't confidently drive on the freeways anymore because I might lose power after ten miles of pushing it past 60 mph. If I stop commuting with the electric vehicle, that takes away 90% of my driving, which makes owning the car somewhat pointless.

The first thing I'm going to do is install a PakTrakr monitor. This is something I should have done a year ago to accurately monitor each battery. The Link-10 E-meter is good, but doesn't monitor individual batteries. For all I know, I might just have one bad battery in the pack. I already have the PakTrakr on my bench, but I haven't had time to install it. I just might do that this weekend.

Some options to consider:
  • Purchase a whole new set of batteries for $3000 (ick!).
  • Spend a lot of time making the car aerodynamic like the Aero-Civic
  • Redo the system with lithium-ion batteries and double the amp-hours for $10,000 and lots of time (ouch!).
  • Sell the vehicle at cost minus the price for the batteries, go with an ICE and buy a Nissan Leaf when it comes out.
After installing the PakTrakr, I'm going to try and commute for a few more days in this colder weather to see if things still work. Perhaps I only need to replace one battery...

Saturday, September 5, 2009

New Vacuum Pump and Fixed Wiper System

Sorry folks, no pictures today. I'm taking this long weekend to just relax and get some things done around the house while avoiding the crazy Labor Day weekend traffic.

One thing that's really been annoying me about the Civic is that the intermittent wiper setting doesn't work. After taking awhile to pry out the ICU (Integrated Control Unit) mounted on the back of the fuse box, I opened it up and tried some tests with a 12V battery to verify failure. After going to LKQ self-service auto-parts, I lucked out and found a Civic with another ICU in it as well as a grey trim piece I was missing. After shelling out a whopping $6.50 for these salvaged parts, I came home, snapped in the spare ICU and the wiper system started working again. Yay! I'm all ready for the long rainy winter here in Portland.

On a more relevant note to you EV folks, I also spent most of the day replacing my old Gast Vacuum pump and vacuum chamber with an MES 70/6E Swiss-made vacuum pump from MetricMind. I was lucky enough that it fit in the same space as the Gast pump and the vacuum tube from the pump to the brake assist chamber is only about 16" long. The MES pump is MUCH quieter than the Gast system, has a built in one-way valve and much less hysteresis than the Gast system. While it cost more ($315 instead of $285), the price difference wasn't that much.

I just finished my first test drive about 30 minutes ago and I really like this new vacuum pump. It's far quieter than the Gast system and has much more even braking pressure due to the smaller hysteresis. While the MES pump does come on much more often, it's so quiet I can only hear it when the car is completely stopped at a light without much noise going on around me. My initial thoughts are very positive and I recommend this for new people converting EVs.

Now that the intermittent wiper system is fixed and brake vacuum pump is upgraded, I don't plan on doing any more work on the Civic for awhile. I think the next major project (If I don't go out and purchase a Nissan "Leaf" outright) is to upgrade the batteries to lithium-ion types when the AGM lead-acid batteries die. Hopefully that will be two years out.

With the downturn in the economy and factory-made EVs being announced for next year, I've noticed far less EV projects happening these days. If people are doing conversions, they're doing them to older, more "classic" cars. These next few years are going to be quite interesting.
Drop me a comment if you're still working on a Civic EV. It's good to hear what projects are going on.

Cheers,
Tim

Saturday, August 22, 2009

Controller Overheating and Vacuum Pump Issues

It's been awhile since I've posted because, well, things are just kinda boring and working well on the Civic-EV. I passed 4,000 EV miles a few weeks ago and things are still moving along.

For those of you who have been keeping track of weather in the NorthWest lately, we had a hot spell at the end of July. One day of that week got up to 107F. I had a bit of a scare coming out of work when I found that the Civic-EV wouldn't start at all. The paint is dark blue (almost black) and the engine compartment was probably up around 115 degrees. After opening the hood and running the fan on the controller for 15 minutes, the car finally started to move forward without faulting.

I made it almost home. Coming off the freeway, I stopped at the stoplight on the exit ramp and the controller faulted and simply refused to go further, despite repeated "reboots" by toggling the ignition key. Fortunately, two wonderful people helped me push the car to a near by parking space across some local light rail tracks (we had to dodge the MAX light rail, yikes!). I let the car sit there until 10pm to cool off. When I came back at 10pm, it started up and I drove home.

Needless to say, I was a bit concerned about this hot weather situation. I contacted Ives, the controller designer at Synkromotive, and told him about the problem. His response: we've had that problem for weeks. All you have to do is turn up your CPU thermal limit from 50C to 85C degrees. Geez, I wish he woulda told me that before the heat wave hit. The car seems to be running just fine now, even on hot days.

Another issue I seem to run into (now that I'm driving a lot more) is that the hysteresis on the pressure switch for the Gast vacuum pump is rather large. This means the vacuum in the system to assist the brakes varies quite a bit. 90% of the time, this is no problem, but the 10% of the time when there is little vacuum in the system, the brakes hardly work at all. I have to pump them a bit to drain more vacuum and get the pump started again. When slowly coming to a stop, this isn't a big deal, but in emergency stop situations, this has been an issue.

To solve this problem, I purchased a $300 vacuum pump from Victor over at Metric Mind that is much quieter than the Gast pump and should have much tigher hysteresis on the levels of vacuum in the system. I haven't installed the pump yet, but I plan to soon.

Other interesting news: I'm resigning as chairperson of the local Oregon Electric Vehicle Association. It's been a good run for the past two years, but I'm tired of running the organization and it's time that someone with better organizational skills to step up.

Ross Peterson just finished his Civic-EV during the past two months based on the open-source Civic-EV kit and he's got the "EV Grin." I was delightfuly surprised to hear that he didn't have many issues building his battery racks based on the open-source plans. His batteries are a slightly different brand than mine, but they are still group 31 size and fit the plans well.

Stay tuned for details on the vacuum pump installation. Otherwise, best wishes on all your projects.

Tuesday, July 14, 2009

Getting a new Synkromotive Controller

After mentioning the motor controller temperature faults to Ives (the designer) at Synkromotive, he suggested we swap it out for a newer one. I went into the shop this evening and swapped out the controller. Ives looked at the old one and basically told me that I had beta test unit #2 with tiny heatsinks, bad ventilation and very little filtering on the temperature fault circuitry. Apparently other customers have had the same issues and the new controller should be far better.

One other thing the folks at Synkromotive showed me was a newer vacuum assist pump for the braking system that's very quiet from EVComponents. It's a bit expensive, but the pump produced very little noise, even with the hood open and my hear near it. Also, to enhance the power steering, they use the electric power steering pump from a Toyota MR2 so that parallel parking isn't as hard. More info here.

So far, the new controller is doing just fine. It also got bumped up to 700 motor amps from 600 when starting from a stop. The tires do a wonderful little "chirp" when I floor it from a stop in first gear before the batteries current maxes out at 300 amps. I could kick both of those up, but choose not to so I can save breaking my transmission and batteries.

I'll try and keep y'all posted on the progress. I'm a bit tired of working through issues right now, so if the car drives well, you might not hear from me for a few weeks.

One other complaint I received was that the open-source Civic plans were not complete on the Civic-EV Google Group. The complaint is valid and I plan on finishing things when the summer is over and I'm past my burn-out stage on this project. I hope to just enjoy driving the car for awhile. The modified charging circuit seems to be doing its job well and I'm happy that problem is over.

In the meantime, I'll be attending the Wayland Invitational at PIR to rub shoulders with the bigwigs in the EV industry at the end of July.

Sunday, July 12, 2009

EV Awareness Day, Synkro faults

Yesterday was our local EV organization's big annual event called EV Awareness Day. We held it at Pioneer Courthouse Square in downtown Portland. I gave a press event with the Mayor Sam Adams and two VPs from local power companies (PGE and Pacific Power).

Probably one of the coolest things about the show is that a Tesla Roadster showed up unexpectedly!


Here I am with the Tesla Roadster.

After talking about electric vehicles to people all day in the sun, I was rather fried at the end of the day.

On the way home the Sykromotive controller faulted three times during initial acceleration up a hill in the summer heat. I suspect these are temperature glitch faults that Synkromotive has been having issues with for awhile. Being fried from the show and caught in heavy traffic on a hill with lines of people behind me, you can imagine this wasn't much fun. Fortunately, I've learned that I just need to toggle to ignition key and wait five seconds to try again.

After clearing the third fault on this hill, I was able to very slowly accelerate up the hill until the motor turned enough to not cause noise issues with the temperature sensors in the controller. I'll be uploading all the fault logs soon and contacting Synkromotive for further advice. Other than the temperature faults, the controller has been excellent. This is still a "beta" unit, so perhaps they've resolved the issues. Let's hope so...

Thursday, July 9, 2009

Super FET working Comments on Sykro Controller

Last week I was mostly on vacation, so I didn't get a chance to really charge the car at full amperage many times. This week was back to work, so I was able to give the charge detector a more reasonable test.

In short, the three huge FETs with heat-sinks seem to work just fine (I should hope so...). I've charged the car seven times in the summer heat and the charger can dump a full 8 amps into the batteries every time without heating up the charge detector box.

I had a little bit of a scare today at work. The Synkromotive controller would instantly fault every time I touched the accelerator. It seems that I had a loose connection between the potbox and the controller. When I wiggled the connector on the TPS (throttle-position-sensor), the controller ceased to go into a fault condition and I drove home. I put anti-corrosion compound on the TPS contacts to help prevent a similar fault in the future. I'll bet that the Sykromotive controller was faulting due to an incorrect input on the potbox wires.

I really like the simplicity of the system. If it fails, it usually fails big and the failure is usually a loose wire somewhere. Get out your Fluke-meter and start debugging.

On my last post, someone left a comment asking about how well the Synkromotive controller was working. In short, it's great. It gives a lot of power when requested and is quite easy to tune various internal parameters through the user-interface over the USB port. Embedded logging makes it really nice as well.

A few nitpicky items I would improve about the controller: The large bus bars that attach to the battery cables are mounted vertically, requiring the use of right-angle lugs or fancy routing of wires. Also, the power given to the motor instantly reflects whatever is specified on the potbox.

If you have a quirky potbox or press the accelerator too quickly, the car seems to lurch a bit. This is especially true if there is slack in the drivetrain from having the motor coast to a complete stop. The lurch instantly takes up the slack in the drivetrain and you can get a jerk that might cause oscillations.

As I've mentioned before, the big solution to this is to use the factory TPS instead of a cheap forklift potbox (like a Curtis PB-5 or PB-6). The factory one is much smoother and more reliable. The downside of the factory potbox is that it never goes to zero ohms which means you can't use it for simpler controllers like a Curtis. The Synkromotive controller has many potbox tuning adjustments so you can set the zero point and the acceleration ramp depending on the travel distance of your throttle cable.

The Synkromotive controller on hot days sometimes gets a temperature noise fault. More recent firmware tends to fix this issue, but I've still stalled once with the latest firmware. Fortunately, you simply need to toggle the ignition switch and wait four seconds for the precharge circuit to run to re-engage the contactor before driving again.

This weekend is the biggest day of the year for our local EV club. We're showing off 30 electric vehicles in Downtown Portland and Mayor Adams is also showing up at our press event to endorse our group. I'm excited but will be happy when it's all over.

Thursday, June 25, 2009

Time to Get a Larger Hammer

After two days of running perfectly, I found yesterday morning that the amps were down and the FET had blown again. This really stumped me because I thought I had done everything to keep it cool and out of the switching region.

After showing the system to the power supply EEs at work, they told me that any FET in a TO-220 case like the one I had would not handle a constant 8-amps for a long time. The heat dissipation comes from the bond wires going to the silicon inside, not the actual silicon itself. They suggested that I put multiple FETs in parallel to lower the resistance and spread the heat over multiple sets of FET bond wires. If you can lower the resistance by half, the power dissipation goes down by a factor of four.

As you might imagine, I'm getting really tired of blown FETs, so I rummaged through our lab stock and got the biggest FET I could find.


Here's a comparison of the FET's I'm using. Instead of one TO-220 case FET on the left, I'm installing THREE of the TO-247 case FETs on the right in parallel with heatsinks. I'll be taking the "on" resistance from 30 milliohms down to 3 milliohms. By dropping the resistance by a factor of 10, I can theoretically lower the power dissipation by 100 (I^2*R from ohms law).


Here are the three high-power FETs installed inside the charge detector box. Note the burnt spot in the lower right corner of the printed circuit board from the smaller, individual FET that burned up yesterday morning.

I just started charging with this new circuit about an hour ago. The charge detector box is COLD. I can barely feel a slight temperature difference between the top of the box and the vehicle chassis.

Some might think this is overkill. Those folks would be right. It probably is, but I'm sick of wasting my own time and the time of all the folks at work who are graciously helping me out. I would rather nuke this one with an overdesigned system instead of having to revisit it several times.


Here's a third schematic (click to enlarge) including the changes to Q1, Q2 and Q3 FETs on the right side.

I sure hope this issue is dead. I've got a few EV shows coming up and I'm done with dealing with this issue. Let's see what happens. Hail Mary.

Monday, June 22, 2009

Cautious Optimism

After talking with the power supply EEs at work, I came home and tried a few experiments to see if I could fix the alternative charge detector circuit.

First, I used an external 12V UPS battery instead of the AUX power output on the Belktronix charger to see if noise on the power supply was causing my problem. Nope: The circuit still behaved as if the opto-coupler latched closed.

Next step was to pull out my oscilloscope and start probing around the system. Fortunately, most of the battery pack and components are floating, so I can attach the ground of the scope to several different high-voltage points to serve as a reference.

Yowzers! There's a hell of a lot of noise in this system. Whenever the Belktronix charger starts up, I get 50V spikes at ~200Khz on the oscilloscope by just holding the tip of the input probe with my finger. Keep this thing away from your pacemaker! I'm guessing that these high voltage noise spikes are causing problems with the opto-coupler.


Here's a modified schematic. The EE folks at work suggested adding C4 (.01uf cap across the opto-coupler input) to help cut down on the noise. I also reduced C3 down to 10uf from 47uf. This reduction increases the maximum switching frequency for the FET (due to the hysteresis in the 555) from 1Hz up to about 5 Hz. While the FET switches at a slightly higher frequency, it's still so slow that the FET stays out of the linear switching region for long periods of time.

I plugged in the system and (gasp), the FET stayed on like I intended it to. After suspiciously pondering the circuit thinking that I had messed something up, I shorted out the OVP signal and the FET quickly turned off and the LED came on. The link-10 meter shows a full 8 amps going into the batteries. In a few hours, the BatMon boards should start lighting up and I'll see if the circuit responds correctly. The charge detector box is a bit warm to the touch, but definitely not hot.

I'm very excited that adding a .01uf capacitor to the opto-coupler input cleared up much of the noise. Someone over in the UK had their Belktronix charge detector blow up too with a lithium ion battery pack, so I hope this circuit can help them too.

After my heated rant last night, I received several supportive e-mails and comments from people. Thanks to all who responded for your ideas and well wishes. I feel good when I hear from folks because I don't know how many people are actually keeping track of this blog, especially since things have quieted down recently.

Let's keep our fingers crossed with cautious optimism. Cheers.

Sunday, June 21, 2009

Failure Again!

I came home this evening after a 20 mile drive with excitement to see the new charge detector circuit work. I plugged in the car and the circuit had an interaction with the optocoupler on the BatMon board and didn't see the correct signal. Nothing is burning up, but the FET is stuck in the off state for now, leaving the system to charge slowly with a really hot 3-ohm resistor.

I'm so angry at this charging system! It's a good thing I just got back from my mindfulness meditation session or I would throw a wrench at the car. God, I'm pissed! It worked so well with the batteries near a full condition, but the circuit fails when the batteries are discharged. I suppose this is a good data point for further analysis, but I'm rapidly running thin on patience.

I'm taking the circuit into a bunch of EE experts tomorrow at work (they always like working on these problems instead of their real jobs) and we're going to get to the bottom of this. I'm running out of energy to get this working. Damn, this sucks.

A New Hope

After the utter failure of the Soneil and the Joule chargers, I did some more research on individual battery chargers. Ideally I was looking for the following:

  • Power factor corrected
  • Weather-proof for mounting under the hood
  • Isolated to work with a series pack of batteries
  • 6-8 amps charging capacity
  • low power enough to put all 12 chargers on one 15 amp circuit (possibly 20 amp circuit)
  • somewhat affordable
I did some more searching and found the BatteryMinder 12248, the Xantrex Trucharge 10, and the Waeco PerfectCharge IU1012. The Waeco units seemed really good but were from Germany with no distributors in the USA. The Xantrex and BatteryMinder units were $150 apiece (ouch!) and didn't meet all the criteria above.

I decided to go back to the drawing board and see what I could do with the Belktronix charger. In concept, the charging system was great. It's a nice power-factor-corrected series charger that dumps out a solid 8 amps and it's sealed so that bugs and dirt don't get in.

Since I've moved to the Synkromotive motor controller, there aren't any more mid-pack taps off the battery pack, so the batteries tend to drift out of balance more slowly. Arguably, the resistive shunts with the Belktronix charging system should be able to handle this quite well.

The problem in the past has been the charge detector. Without going into all the details of operation, the OVP lines from all the BatMon modules would pulse and cause the FET inside the charge detector to turn on and off. Since this pulsing was frequent, the FET was often in the switching region and easily overheated.

The FET inside the charge detector determines if the large 3-ohm 180-watt series resistor is inserted in the charging circuit. If the FET is on, then the 3-ohm resistor is shorted and the batteries get a full 8 amps, which is great for fast charging. This brings up a problem when the BatMon boards detect a "full" condition on the batteries. The small 3-ohm shunt resistors start to burn up if they have to sustain the 8 amp current flow. Thus, the charge detector needs to turn off the FET to insert the large series 3-ohm resistor to limit the current. If you turn off the FET too early, it takes forever to charge your batteries and the large 3-ohm series resistor gets really hot. Turn off the FET too late and all your shunt resistors burn up, causing massive smoke and potential fires in your EV. (ugh)


Here's a picture of the inside of the blown charge detector. The FET is clearly blown in half with burn marks all the way around it. Note the melted region on the case cover in the lower right.

The FET in the charge detector is a very good one with a very low turn-on resistance. If we can limit the amount of FET switching and turn it on/off hard to keep it out of the linear region, it should stay relatively cool, even with 8 amps flowing through it. So, I put on my EE hat and designed a completely new circuit to put inside the charge detector box.


Here's the charge detector box with the new circuit inside of it. The circuit (shown at the end of this post) uses the comparators and flip-flop inside a 555 timer (Radio Shack special!) to drive the FET with hysteresis on the input to limit switching.


Here's my old Radio Shack 555 timer handbook. It's a crying shame they don't sell these anymore. I guess it doesn't make a profit and people just aren't into dinking around with 555 timers anymore. As you can see (click to enlarge picture), this tiny chip contains two comparators, an RS-flop and an output driver. This is just what we need to observe the pulsing OVP signals from the Batmon boards to determine if we should turn the FET on and off to short the large 3-ohm series charge resistor.


I tend to go overboard with these things. This is my kitchen table with all the soldering/test equipment on it.


Here is the simple circuit I put inside the charge detector box to control the FET that shorts out the large 3-ohm series charging resistor. Note that this lacks a few safety features that would prevent a blow-up if the user hooked things up in reverse, so this is not a product-worthy circuit. It's simple enough and you can get most of the parts (except the FET) from Radio Shack. If you click to enlarge the picture, you can see the theory of operation and get more details.

I'm going to try this out for a few days and see if I can charge faster without blowing up the FET. The potentiometer still probably needs adjustment to properly set the duty-cycle detection on the OVP pair, but this is a good start. If this works, I'll have fast charging without setting the small shunt resistors on fire. Here's to hope...

Friday, June 19, 2009

A Very Dark Day with the Joule Chargers

This whole experiment with the individual chargers has been a very humbling experience.

After the whole set of failures with the Soneil chargers, I learned from the distributor that the 1214S model doesn't support series strings of battery packs:

Tim,

Well, based on this email I sent an email to Soneil. Apparently there has a
been a design change in some of their chargers (these included) which
prevents you from being able to charge while in a "series" configuration.
This means that the half with no LED are dead. This also means you can't use
that charger type with that configuration. I apologize for this huge
inconvenience, I have no idea why they would change the design. The closest
12v Soneil charger we have that does not have this design change is the
1212SR, but it is a 5amp and is $89.95ea. We can refund your order or
replace the same value with 1212SR chargers, I'm not sure what else to offer
you. Both issues you have found have been somewhat unbelievable, I apologize
for the "luck" on this. For the electric bike application, both charger
types work great. The electric car application has a few unexpected
differences....

Thanks,
Mike (from ElectricRider)

After hearing the above, I returned the Soneil chargers and asked ElectricRider to ship me a set of their in-house Joule chargers (model JJ12060). Their technician insisted that the chargers should be fine for a series connected battery pack.

About a week later, the box full of Joule chargers arrived on schedule.


Here's the pile of twelve Joule chargers after I stripped off some insulation and added ring terminals for the batteries. I'm really excited because these are smaller than the Soneils and have integrated cooling fans. Despite the 35-40mA current draw, I'm full of hope that these will solve my pack imbalance issues.


After installing several of the chargers, I observed the following:

  • One failed to even start up (LEDs were flickering)
  • Six didn't have their fan come on. I thought that the fan might come on after the charger heated up, so I left one on for 20 minutes. The unit overheated and ceased to work. One of these six had its 100% charged LED stuck on, possibly indicating other issues.
  • Five powered up correctly; however, the fan on two of them seemed to get up to speed very slowly, possibly indicating fan bearing issues.
In short, I'm very disappointed with these chargers. They have a one-year warranty, so I could send the bad ones back for replacements. I purchased thirteen of them, assuming that one would be bad. The > 50% fallout rate greatly concerns me. In addition the PFC (power factor correction) value for these chargers is about 0.6 which roughly means only 60% of the input power gets to the battery and the other 40% gets dissipated as heat in the charger. No wonder these things get so hot!

I'm taking a day to ponder my alternatives. The Belktronix charger has a lot more "spaghetti" to it as well as hot shunt resistors. On the flip side, it has a very high PFC value which means that the primary charger is quite efficient and it doesn't heat up much. The charger is also sealed, making it much more resistant to dirt and bugs.

One option I'm considering is replacing the shunt resistors on the Belktronix charger with 50-watt halogen light bulbs. This means some of the shunted energy gets converted to light instead of heat. I'm also looking into a circuit to replace the charge detector in the Belktronix system.

EV Awareness Day here in Portland is only three weeks away and I've got to get this beast charging correctly. Here's to being stubborn. Stay tuned.

Sunday, June 7, 2009

Sleuthing the Soneils

Against my better judgment, I took apart one of the failed Soneil chargers yesterday afternoon to see if I could find out anything about the failures. There weren't any burned components or obvious damage. After powering up the unit with the cover off, I could verify that the isolation transformer between the AC side and battery side wasn't getting pulsed, and thus passing no power to the battery (or the LED). It seems that the UC3842A chip DC-DC converter chip used to drive the FET which pulses the transformer was dead. It's power supply had a resistance of about 3 ohms to ground (bad).





After mulling over the circuit in my head last night. I tried to compile a list of facts I know about the failure:

Facts:
  • The batteries were all fully charged in the morning, despite the charger failures
  • The batteries with working chargers had ~13.7 volts on them, the failing ones, ~13.4
  • There were far more failures in the batteries in the front of the car
  • The front batteries are closest to the negative pack voltage
  • I plugged in the rear batteries first when testing the chargers
  • The rear batteries typically have slightly more charge on them because they get warmer
  • I started all rear battery chargers simultaneously on a power outlet strip
  • I started all front battery chargers one-by-one by plugging them into power cords with three outlets on the end
  • The components crossing the isolation barrier in each charger are: a transformer, an opto-isolator, and three ceramic capacitors (.01 uF at 250V)
Hypotheses:
  • Since all batteries were at nearly full charge, the failure must have happened at the end of the charge cycle, perhaps when the charger transitioned from acceptance charge (14.7V at 3.5A) to float voltage (13.7V)
  • Since the front batteries typically finish charging last and I also plugged them in last, perhaps a surge from the rear battery chargers (when shutting off) caused failures in the front battery chargers
  • Is suspect that the capacitors at the isolation barrier in the chargers failed because they have a breakdown voltage of 250V. When charging one battery, this is fine. When charging a long series string of batteries (oh, say, 144V), the charger output stage can float +/- 144V relative to the AC voltage on the input stage. 120V AC really becomes 170V DC when rectified. Add this to 144V and you get 314V, which is clearly above the 250V rating in the isolation capacitors.
Based on this, I don't think sending the chargers back for replacements would really help the situation. If all the chargers have the same 250V isolation caps, then they would all fail eventually. I suppose I could take all the chargers and replace the isolation caps with similar values but give them a 1KV voltage rating.

I'm trying to figure out the best option for now. To drive the car, I'll probably need to re-install all the Belktronix resistive shunt balancer modules. The car would be driveable but it would still take a long time to charge. I don't like the idea of hand-modifying twelve Soneil chargers, but that would probably be what it takes to get them working.

I could send all the Soneil's back and get the Joule chargers again. That is, after checking with the designer that they support 1KV of isolation. The Joule chargers draw 35mA of current when sitting there unplugged. This hypothetically translates to 2857 hours of discharge from 100Ahr batteries or about 4 months until the batteries are completely dead. If I went on a long vacation, I guess I would leave the chargers plugged in on float charge anyway. The Joule chargers also only charge with 6A, which means (despite a bad PFC rating), I might be able to plug in all chargers to a 15 amp AC circuit (The Soneils pull about 18 amps for all 12 chargers).

This is a really bad time because we have so many electric vehicle events happening now. Having a dead EV is not too appealing. I'll ponder this for a bit.

Happy Sunday morning.

Saturday, June 6, 2009

A dark day with the Soneils

This morning was a dark morning.

I received the Soneil chargers yesterday around noon and stayed up until 11:30 last night to install them. After installation, I powered them up and all chargers lit up with an orange LED. Yay. This morning, I got up and half of the chargers had a green lit LED and the other half were dark. I used a Kill-a-Watt meter to determine that the dark units were pulling no current at all.

I've heard rumors that Soneils don't like to be attached to a series pack.

It looks like my EV is dead for the near term. Putting the Belktronix system back in with all of its shunt resistors and battery boards does not sound appealing right now.

Ugh.

Friday, June 5, 2009

Fixing the Potbox, Soneil's Arrive

Over the past few days, the car has still been lurching around despite the potbox parameter adjustments that I've made inside the controller. I contact Bob Bath, the original CivicWithACord builder who sold me my PB5 potbox. It was brand new from KTA Services and not used/worn-out. Yesterday in stop-n-go traffic, the car was lurching again and the controller faulted when I haphazardly floored the accelerator with the car out of gear. After expressing my frustration, Ives at Synkromotive highly recommended that I install the factory throttle position sensor (TPS) from the original Civic instead of using the PB5 potbox.


Here's the factory Civic TPS installed. I mounted in the same place as the PB5 potbox, but used a piece of 1.5" angle iron 4" long to mount it. Unlike the PB5 which only has two wires, this TPS has three which allows for higher reliability and more accurate signalling to the controller.


Here is the rear side of the installation. You can see the top of the grey-painted angle iron that I bolted to the engine mount side. I had to chamfer one corner to prevent interfering with the engine mount rubber. The actual electrical potentiometer is black at the far left of the picture, while the cable attachment is on the far side of the large butterfly intake valve. There were some extra bolt holes in the throttle housing, so I just used a piece of all-thread and bolts to suspend a small piece of 3/4" angle iron to support the fixed point on the throttle cable.

After a test drive, the system was sooooooo much better. I can creep forward with the car now and the lurching is gone except when I really stomp on the accelerator. I'm now completely convinced that the PB5/PB6 potboxes are complete crap compared to the factory throttle position sensor. It's too bad the TPS doesn't go down to zero ohms, so it can't be used for many other controllers like a Curtis.



After I arrived back home from the test drive, the FedEx truck showed up and dropped off 13 brand new Soneil 7amp chargers. I've been waiting for these for over a month now and am happy they are here. This will replace the Belktronix charging system and allow me to remove all the spaghetti associated with the shunt resistors and battery monitoring boards.

This is a good day. The car is running smoothly again, and I'm psyched to get these new chargers put in. Have a great weekend everyone.

Cheers, Tim

Sunday, May 31, 2009

Moving the Instrumentaiton

Since the Synkromotive controller has its own motor speed limiter based on input directly from the Zolox sensor, I decided to clean up the instrumentation by removing the RPM gauge and moving the Link-10 E-meter onto the dashboard. While this removes some of the "coolness" factor without a tach, I like the more simplistic look as I tend to be a minimalist.


Here's the empty pillar pod with the gauges and wiring removed. I'll probably run the local Civic used-parts store and simply get a piece of replacement trim.


Here's where I moved the E-meter to. I can actually see it quite well when driving. It's sitting in the same hole where the defroster button used to sit. I simply carved a rectagular hole in the dash and moved the defrost switch down a few inches. It protrudes a bit, but still works fine.

In addition to moving the gauges, I wired up the "oil" light to the warning light on the Synkromotive controller. The oil light requires it's input wire to pull down to ground. Since the motor controller puts out a +12V signal when there's a fault, I used a simple transistor circuit (see the schematic at the end of this post) and drove the transistor gate through a 3.3K ohm resistor.

Synkromotive Potbox Issues and Temperature Faults

Over the past week, I've been able to give the Synkromotive controller some good real-world experience during my commute. The controller is very smooth and has several parameters to keep the battery pack healthy. I also like that the Synkro controller doesn't tap off the main pack for part of its power supply which has led to pack imbalances in the past. You can see several voltage-current graphs on the Synkromotive website here. Click on SynkView at the bottom. You'll have to install MS Silverlight to see the graphs. Click on Logfiles/Civic and then an .XML file on the right to see various drives.

One major issue I had was that the car tended to lurch when first starting up. This isn't too bad on the freeway, but can be a real pain when in stop-and-go traffic. Last Thursday I was driving home in hot weather in stop-and-go traffic on the freeway in the middle lane. The car seemed to get progressively worse during the drive home with its "lurch-starting."

About 2/3 of the way home, the controller faulted and just stopped the car dead in the middle of the freeway. I attempted to clear the fault and get the car started again by turning the ignition key off and on. I must have been impatient (sometimes it takes a full six seconds for the controller to precharge and be ready), but I wasn't able to clear the fault. Traffic was slow, and two kind men helped me push the car off the left side of the road. This was a somewhat unnerving experience, but I guess it's part of the game when trying out a Beta-test motor controller. After propping open the hood, removing the primary 12V power from the controller and hard-booting it, it seemed to start up again and I drove the rest of the way home.

The beta controller units have been having a few issues with noisy temperature sensors. During initial acceleration, the electrical noise tends to cause a spike in the temperature sensors, causing the controller to shut down. After I got home from this incident, I observed some of the potbox inputs (Ainput in the Smi window) and realized that I have a really crummy PB5 potbox. The resistance goes from zero ohms and jumps up erratically to 400 ohms or so and then goes smoothly up to 5K. With this new information, I was able to set the "zero throttle" point above the 400 ohm point which makes acceleration much smoother and bypasses the glitches in the potbox.

Yesterday, I was driving someone home in the Civic. Again, it was a hot day and we were in stop-and-go traffic. The controller faulted again and shut the car down. Fortunately my friend, who was in a hurry, could walk the remaining eight blocks home while I rebooted the system. Ives at Synkromotive gave me some updated firmware with some extra noise filtering on the temperature sensors. After running the car through the same route with the new firmware and doing some extra stop-and-go testing, I couldn't get the controller to fault again. We'll see what happens the rest of the week.

Despite the faulting condition, I've been extremely happy with the power, smoothness, logging and programmability of the Synkromotive controller. This is going to be a really good product when it hits the shelves in July.

Going to the Electrathon/HPV Event at PIR

Last weekend, I took the Civic-EV to Portland International Raceway to show it off at the Electrathon/Human-Powered Vehicles event there. Memorial Day weekend is the one weekend that PIR can't make any loud noises, so they actively recruit electric vehicles and bicycles of all types to race.


Here's Gary's Honda Insight EV with lithium ion batteries and an Siemens AC motor.


This shows some of the velomobiles (encased recliner cycles) present at the event. They really fly.


Here's my humble Civic next to Paul B's Corbin Sparrow.

It was really hot that weekend, but the new controller held up well on the freeway.

Saturday, May 23, 2009

Installing the Synkromotive Controller

I stopped by the Synkromotive shop this morning and picked up my beta-test controller that I've been wanting to try out. After running out and buying some more magna lugs and welding cable, I came home and removed the Belktronix controller and all the associated wiring.


With the old controller gone, I had to figure out how to place the new contactor and controller. Here's my mock placement. I placed the contactor slightly behind the controller to limit the cable lengths I would have to use and keep the high-voltage connections away from eager fingers. After the placement, I removed the piece of thick plastic below, drilled some mounting holes and bolted the controller and contactor in place.


This picture shows all the high-voltage 2/0 gauge cable hooked up. I was very fortunate that I could reuse all the old cables and simply crimp on new lugs. My purchase of 12 extra feet of 2/0 gauge cable was for naught, but I'm glad I got it anyway since the welding shop is only open on Friday.

The high-voltage connections on the Synkromotive controller are well thought out, especially if the controller is near the motor and parallel to it. The funny downside is that the connector bars are vertical instead of horizontal, forcing me to use less-common "L" lugs on the 2/0 cable to attach things. I'll have to give this feedback to Synkromotive.


Here's the preliminary installation. I don't have the motor RPM sensor hooked up yet, but I wanted to get the system going because there's an electric car show this weekend at PIR (we're demonstrating EVs along side the Electrathon and Human-Powered-Vehicle folks).

The Synkromotive controller is fully digital and has a USB port on the side. After firing up the user interface program, I was able to verify that everything was mostly operating. Given that this is a beta program, documentation is slim at best and full of bugs. I've already given much feedback regarding specific points in the document that cause confusion.

After checking all the voltages, I rotated the potbox by hand with the transmission in neutral and (Voila!) the motor spun. As of 11:30pm, I took it for a quick test drive around the block. The acceleration was very smooth; however, it wasn't as peppy as I had hoped. The amps never got above 150, so I'm guessing there's some calibration I need to do with the potbox. Anyhow, after 7.5 hours, I successfully swapped out the old controller for the new.


I'm a big fan of an uncluttered engine compartment. While the Synkromotive controller definitely has some wiring, the Belktronix system was a bit more out of control. Here's a bunch of the "spaghetti" that I removed with the older controller. I like seeing the removed chaos in a box.

Once I get the individual Soneil chargers, I can remove additional wiring and clutter without all the shunt balancer boards on top of each battery.

Whoosh, I'm liking this new controller! Tomorrow I'll tweak settings a bit more and see if I can take it on the freeway to PIR for the show.

Cheers,
Tim

Sunday, May 17, 2009

Installing a New Potbox

As with many EV projects, much time is spent waiting for parts. The replacement Soneil chargers haven't shown up yet. On a more positive note, Synkromotive figured out some of the glitches in their new beta controller, so one should be available this coming Friday. This new system will require a different potbox, contactor and other wiring.

I'm excited to install the controller, so I installed a new potbox to get ready.


Here is a view on the driver side in the engine compartment just above the engine mount. I'm going to use the two holes in the engine mount bracket to mount the potbox.


Here's the PB-5 potbox that I purchased from Bob Bath with an aluminum bracket bolted to it. I was fortunate enough to keep this around in my pile of parts because it fits very well.


Did you notice the shiny silver thing attached to the arm of the potbox above? I had difficulty trying to figure out how to attach the acclerator cable to the arm of the potbox. The guy at the hardware store suggested that I use one of these tiny cable clamps. The "U" bolts fit perfectly in the holes on the arm and I can clamp the cable down tightly.


Here's the potbox mounted in place. Notice how it's tilted slightly to the left and not in parallel with the E-meter DC-DC converter in the black box to the right. This is because the accelerator cable interferes with the top of the shock tower if the potbox is mounted inline with the car. This leftward tilt moves the cable just inside the shock tower so it hangs better.


Not only did I have to attach the acclerator cable to the potbox arm, but I needed to mount the housing on th end of the accelerator cable in something so the cable could pull against something. To accomplish this, I took a spare piece of 3/4" angle iron and drilled a 5/16" hole in one end, near the edge. I then cut out the hole with a hacksaw to get this keyhole-like shape. This will allow the cable housing to slide in at its narrow point but not pull out when I slide it forward so that the wider threads sit in this 5/16" hole. I also drilled a 3/16 hole in the other angle iron face to mount this tiny piece with an 8-32 by 1/2" bolt.


Here's a piece of flat bar that will hold the cable housing. The two holes on the left are the same distance apart as the two posts on the potbox. The hole on the right end is where I'll mount the tiny piece above so the cable has something to push against.


After sawing off the tiny piece from the end of the 3/4" angle iron, I mounted it to the flat bar with an 8-32 x 1/2" bolt and nylock nut to keep it from falling off. This will rotate a bit and allow the cable some play as the potbox arm swings back and forth.


Here's the above bar mounted to the potbox with 8-32 x 1/2 button-head bolts with lockwashers.

Here's the same picture above, but with the cable mounted in it. The trick is to get the bracket on the right in the correct place so that you can use the two adjusting nuts to properly tension the cable so it gives maximum throw and stops at the zero point on the potbox.

Stay tuned for Friday when, hopefully, the controller arrives.

Saturday, April 18, 2009

Researching a Paint Job

One of the downsides of a home-EV conversion is that most of them don't have air conditioning. The AC tends to suck precious power from the battery and adds extra weight to the car while taking up space that could be used for batteries.

Thus, it's often best to get a white (or light colored) donor vehicle to repel the sun's rays during the summer. The conversion vehicle I purchased is dark metallic blue, which get's really hot inside, even on a mild day in the sun.

So I called a bunch of different car painting places to determine the cost of painting the car white. Much to my dismay, the places that got good local reviews wanted at least $3500 to paint the car. The local Maaco paint shop (which got horrible reviews) wanted $550 for their bottom-of-the-line paint option.

In short, I guess I'll be rolling down the windows and using a reflective shield under the glass for the near future. Note to self: purchase a white conversion car next time...

Planning to Replace the EV Components

In a month or so, I'll be getting a beta-test motor controller from Synkromotive which will have a variety of programmable features as well as more power. Since I'm replacing the controller, I looked into replacing the other components with off-the-shelf items that might work better than the current Belktronix system I have.

Here's the plan:
- replace the controller with the programmable Synkromotive unit
- replace the optical potbox with the original Civic TPS (throttle position sensor)
- replace the charging system with a bunch of individual chargers (Joule or Soneil)
- replace the integrated DC-DC converter with an IOTA DLS-45 unit


Here's a picture of the IOTA DLS-45 DC-DC converter on the right that I purchased at Northern Arizona Wind & Sun for about $150.

On the left is a jj12060 Joule individual battery charger from ElectricRider, supposedly modelled after the popular Soneil chargers. I purchased 13 of them, 12 for the batteries and one extra in case something dies or I need to charge an external 12V battery. They were out of Soneil chargers and said that the Joule was a drop-in replacement with the same specification (right!).

As is typical, things didn't go as planned. I saved this weekend for removing the old charging system and installing the Joule chargers. As a safety check, I clipped a Joule charger to one battery to observe its behavior. When I attached the charger, I heard a click (like a relay) from inside the charger. Hmm, if the battery is always powering an internal relay, then there's a constant current drain (that's bad).

I checked the current draw with an ammeter and found that the Joule charger pulls 35ma out of the battery when it's just sitting there! The Soneil chargers have the feature of not pulling ANY current out of the battery when attached but not plugged into the AC source.

In short, the Joule chargers are NOT a drop-in replacement for the Soneils and I'm going to return them and get Soneils instead.

Argh, more delays. At least the weather outside is beautiful and I can go for a hike.

Have a great weekend everyone.

Taking a Vacation

It's been over a month since I've blogged about the Civic and people have started to ask where I've been. I'm still commuting (even with a blown charge detector) and the car has 1500 miles on it. Several events have happened with the Oregon Electric Vehicle Association (of which I'm the Chair) and I also went on vacation.

At the end of march, I went on an amazing backcountry adventure, skiing the Wapta Traverse with a 45 pound pack on with Randonee' skis.


Here I am near the start of the trip. The scenery was mind-blowing.


Here's the group all roped together just behind an enormous crevasse, heading up to our high-point on the trip. The picture just doesn't do this justice.

Now that I've recovered from the trip, I'll be getting back into trying to fix the charging system.

Stay tuned.

Thursday, March 12, 2009

Charge Detector Blown Again

A few days ago, something funny happened to the vehicle. I drove home and my LVP light came on earlier than I expected. When I got home, the front battery was rather lower than the others in the pack. I attributed this to being just behind the front grille where a lot of cold air is blowing in. to remedy the problem a bit, I slide a large sheet of foam-core board between the batteries and the radiator grille which gives a bit of insulation and forces the air go around the side.

After measuring my batteries for several days after that, they seemed much better, but still didn't seem to get fully charged when sitting at work. Again, I attributed that to the low temperature around here (mid 30's).

Today, I drove home, plugged in the charger and just checked to see if the charge detector was working. Sad to say, the FET has probably blown open again since the OVP lights were not on and lots of current was dumping through the large external 3-ohm charging resistor, making it really hot. This would definitely explain the slow charging.

After trying to fix this device several times, I have a few options:

- fix it again (and wait for it to blow again)
- send the charging system back to Belktronix to get upgraded to a Gen2 system without the charge controller for about $400
- dump the Belktronix system altogether and go with something else, like individual Soneil chargers (Rob Connelly did this and is happy with the results)

I'm not sure what I'm going to do. The existing charger works, but it's just a bit slow. I'll ponder this over the weekend. I have an OEVA meeting to lead this evening.

Ugh,
Tim

Saturday, March 7, 2009

1000 Miles and Still Going...

There's not too much to report on the Civic. I just passed 1000 miles yesterday and it still seems to work fine. I've definitely noticed over the past several weeks of commuting that my range is highly dependent on my speed. Even driving at 55mph instead of 60mph on the freeway gives me a few extra percent of battery life on the Link-10 E-meter.

I've ended up driving with the LVP protection disconnected from the Belktronix controller because it tends to make my speed go way down even though I have plenty of battery left. The LVP circuit is still attached to the battery light on the dash, so I know when to start being very careful of my driving habits.

The charging system seems to be working fine now that I have the BatMon boards inside boxes, protected from the elements. I've driven in a hard-driving rain several times without any problems. The final voltage on the batteries differs slightly from battery to battery due to the analog nature of the Batmon circuits. The BatMon boards rely on the calibration and tolerances of analog components to activate the shunt resistors at 14.5 volts or so.

I'm starting an experiment with several prototype digital battery monitoring boards from Synkromotive. I'm going to see if I can determine which battery is causing the LVP fault earliest with this monitoring system. For you circuit geeks out there, the Synkromotive system (prototype only at this phase) has a 12-bit A2D converter which makes it more accurate than the PakTrakr system used in many EVs today. Those extra bits can make a big difference when your batteries are close to the end of charge and the balancing system needs to compensate for small differences like 50mV. The digital nature of the system (each battery gets an 8051 microprocessor) allows for easy adjustment of calibration values in case things drift over time.

I'll report back when I get some more results.

Cheers,
Tim

EV Driven Link

A few weeks ago, I added an "EV Driven" link to the right menu bar of this blog. EV Driven is a group of folks trying to spread the word about EVs and are behind the upcoming movie Revenge of the Electric Car. It contains several searching features for this blog as well as many other blogs related to electric vehicles. Please check it out when you get the chance.

Cheers,
Tim

Thursday, February 12, 2009

Fixing the Charging System...Again

After doing another fix to the Charge Detector box on Monday, I enclosed all the BatMon boxes to prevent them from shorting out due to grime and automotive fluids.


Here are the plastic boxes I talked about in a prior post. They are held in place with velcro adhesive tape and the box lids are held together with red electrical tape. I don't seem to be having any trouble with overheating (yet...) and the clear plastic lets me see the OVP/LVP lights.

This has been my third week of commuting and I've got 550 miles on the car. It's been fun to drive and show off. I sold my other EV (Porsche 914 at 914ev.blogspot.com) last Sunday, so I'm glad to not have three cars to deal with and the associated insurance.

I'm going to take a break now and just enjoy driving the car, hopefully without too many charging issues. About a month from now, things are going to get interesting again because I'll be trying out a beta test controller from Sykromotive. It's much more programmable, so we'll see how it goes.

Have a great week, everyone.

Wednesday, February 4, 2009

Thoughts on the Kit and Belktronix System

With 350 EV miles on the car, I'm ramping down on fixing things and ramping up on commuting. Before I forget all the stuff I've learned, I'd like to capture some thoughts about the Open-Source kit and my experience with the Belktronix system.

Good points about the open-source Civic-Kit:
  • I really appreciate keeping the clutch. It makes shifting much easier and makes the car feel like a regular vehicle
  • Choosing AGM batteries was a great idea. No hassle with plastic boxes and they put out a punch of current. No acid spill either.
  • The kit involves no welding (metal or plastic)
  • There's no cutting of the chassis to attach parts or install batteries, only drilling holes
  • The kit keeps the spare tire and quite a bit of trunk space while still seating four people
  • Choosing the 5th generation Civic was a good choice for curb and gross vehicle weight. It is also simple to tap into the gauges and electrical system since it's before the advent of complex CAN-bus based systems
  • The use of coil-overs with custom springs makes modifying the suspension so much easier than trying to put stock springs from a different car on the Civic struts. It costs a bit more, but allows for variances between Civic models and battery choices.
  • Picking a standard group-31 size of AGM battery makes the kit flexible and upgradeable
Improvements for the Kit
  • As with many engineering projects, documentation is rather sparse at this point. I think I captured quite a bit of stuff in pictures on the blog, but the official document is only about a third done and not reviewed.
  • The trickiest part of mounting the batteries was desigining the firewall rack. The tolerance between the motor adapter and the underside of the hood is very tight. Too low and you put lots of weight on the motor adapter. Too high and the hood won't close, even with denting in part of the support struts.
  • The vacuum pump is loud. period. I still haven't figured out a good valve pressure switch so that it maintains the right pressure at all times, but it's accepatble so far
  • For my car, I would have liked to get a white car to handle the heat in the summer better. Last summer, the dark blue car heated up quite a bit. Maybe I'll opt for a sunroof
Positive notes about Belktronix controller system:
  • I appreciate the holistic package that Belktronix provides with all the needed parts for a reasonable price
  • Documentation is excellent with lots of diagrams and troubleshooting hints
  • Support is excellent and prompt. You get to talk directly with the designer and don't have to escalate issues to get someone who knows how the system works
  • The vehicle Integrator module is great at telling you the status of the system through LEDs. The precharge sequence for the contactor works well.
  • I like the optical potbox. It mounts easily right under the accelerator pedal and will never suffer from mechanical degradation.
  • The controller seems very smooth and puts out good power. I haven't driven with something similar like a Curtis 1231C, but it accelerates smoothly
  • The battery shunt balancing system puts the shunt resistors off-board to prevent heat buildup near the battery. This also allows placement of the shunt resistors near a fan or other vent.
  • The external thermistor on the BatMon boards allows measuring battery temperature where it is most accurate. I've heard that putting it right on the battery terminal offers the least thermal resistance to the actuall internal battery temperature.
  • The Batmon boards offer individual low-voltage protection (LVP). The controller shuts down when the lowest battery reaches 10.8V instead of just monitoring the whole pack voltage. This prevents killing the lowest battery even though other batteries are okay
Improvements to the Belktronix system:
  • My biggest beef with the Belktronix system is the lack of programmability. It's an analog system where one needs to tweak resistor values to change any parameter. I can't argue that much since most other controllers are also analog in nature, but it would have been nice to change the acceleration curve or LVP cutoff voltage through a laptop.
  • I still need to figure out the LVP circuit. When the battery reaches 50% DOD, I lose all power and can barely creep along at 20mph. I have a bypass switch to get around this, but that disables any LVP protection I might have had.
  • The Batmon boards require quite a bit of wiring which makes the engine compartment look much like spaghetti. It also lends itself to reversed wires or shorts with the wrong terminal leading to blown BatMon boards or a blown Charge Detector. One company added two RJ-45 connectors to their battery boards and just used ethernet cable to wire everything up. No hassle with accidentally swapping or shorting wires and a much cleaner install.
  • I'm concerned that the Belktronix system taps off the main traction pack to power the contactor and the controller, where many others use the 12V accessory battery. This exacerbates pack imbalance and puts a higher load on a subset of the pack. I'm concerned this will cause the pack to degrade more quickly (or diverge more quickly).
  • The BatMon boards are just bare boards (with a protective coating). In the trunk, that's not a big issue, but in the front engine comparment, I've already had issues with fluids like the windshield washer fluid causing intermittent OVP faults. These definitely need to be enclosed.
  • One minor issue is that the controller system doesn't have an over-rev input on it. Bryan at Belktronix worked with me to make an interface that plugs into the back of the tach to create this function, but it's a bit messy. I realize this is problematic since it's hard to set the RPM limit without programmability. Many other systems don't have this feature either.
Overall, I think the controller is fine but the charging system needs some big improvements, especially the wiring spaghetti and bare BatMon boards.

Onward to more commuting!