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...


David Harrington said...

Did you insulate your batteries? I did and it made a huge difference, from crawling the last 2 miles of my trip to getting there with lots of power left. Outside temp would be 48F and I could have the batteries at 89F when charging.

And all it takes it one battery to take down your pack. I had a single battery die early and it took my whole pack down in an instant. I ended up replacing most of my pack under warranty, but it actually needed some equalization.

Ross Cunniff said...

I'm actually adding a heating system to my battery pack. In addition to reduced range at lower temperatures, I found I was undercharging my pack since my chargers do not have temperature compensation. I'm planning on using Gro-Quick soil warmers with a built-in 74 degree thermostat.

David Harrington said...

What is your range currently? And have you gotten a PakTrakr or taken a volt meter to each battery?

TimK said...

Hi Ross and David,

Thanks for the suggestions. Ross, I like your idea for the Gro-Quick warmers. David, I just installed the PakTrakr today, but the calibration was way off (see next post).