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...

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