Saturday, February 6, 2010

Analyzing PakTrakr Files with PrestoPlot

I took the Civic out for a spin today with my neatly installed PakTrakr and captured some data while pulling some reasonably high currents.

I programmed the Synkromotive controller to limit the battery amps to 250 to help prolong the life of the batteries. It takes a bit of the acceleration edge off while on the freeway at 60mph, but otherwise, the power is just fine for commuting.

After loading the PakTrakr data into Excel 2000 (yeah, I know it's old...), I experience much frustration with trying to zoom into areas to analyze the data further, especially peak areas.

I turned to a freeware plotting program that we use at work for quickly analyzing performance data called PrestoPlot. After loading the comma-delimited-data from the PakTrakr log file into Excel, I removed all but the battery voltage columns and added an incrementing list of numbers as a first column. I can now export this as a tab-delimited textfile from Excel and import it into PrestoPlot for easy viewing.

Here's an exported image (click to enlarge) from PrestoPlot showing the whole dataset gathered from the PakTrakr. The data seems very spikey and I was concerned that some of my batteries were dipping lower than other.

Upon quickly zooming in with PrestoPlot, I was able to see that the big droops on one battery were accompanied by positive spikes on the adjacent battery. Note the green dashed lines in relation to the red dashed lines in the picture above (click to enlarge). Hmm..., sounds like the PakTrakr isn't filtering out noise quite as well as I'd hoped.

In areas where the system is rather quiet, the batteries seem quite well balanced. Perhaps my pack isn't as dead as I thought it was, but it has just lost a bit of capacity. Perhaps putting some 0.1uF capacitors on the adjacent signal lines going into the PakTrakr might help with this.

Not too sure what to do at this point, but at least I get a good clean sampling stream on the serial port under heavy acceleration.


Thursday, February 4, 2010

Mounting the PakTrakr

It's time to mount the PakTrakr on the dashboard.

Since I have a low-end model Civic, there are several unused accessory plates that I can tap into. Here's one that I popped out just to the left of the steering wheel. I drilled holes in the pop-out plate to match the mounting threads on the PakTrakr as well as a 1" hole to thread the wires through.

After taking off two nuts on the back of the PakTrakr, I decided to disassemble the whole thing just to see what was inside.

Here's the PakTrakr threaded through the pop-out plate with the nuts holding it on.

Finally, the PakTrakr is installed where I can see it reasonably while driving. Most of my information will come from the Link-10 E-meter, but if I want to see any bad batteries, the PakTrakr should display those.

I've routed the signal cable to the PakTrakr. I also routed the serial output cable with a serial extender and a serial to USB adapter around to the passenger side so I can plug my laptop into the Synkromotive controller and PakTrakr at the same time with USB ports. The car is looking much better than it did awhile ago.

One thing I haven't done with the Lifeline traction batteries is to run a conditioning charge on them. Yesterday I ordered a 0-30V 6 amp power supply so I can run a higher voltage charge on each individual battery. Perhaps that will help them regain some of their life.