Monday, October 22, 2012

Battery Woes

The last few days I have been trying to get my battery pack in as good of condition as possible. This is relatively speaking, of course, because these are all used "dual purpose" group 31 batteries taken out of heavy trucks.

Last week I replaced one battery because after it took forever to charge, it failed my half CCA (350 amp) 15 second load test, sagging to 7.0V. 9.6V is minimum for a good battery.

The next day I went out for some errands on an 11 km long run and I barely made it home because the pack was sagging so hard by the end (down to 49V on acceleration at one point!). So the next day after driving to work and before charging, I gave each battery a 200 amp load test and found all batteries sagging to 10.3V-10.8V except one that was sagging to 8.5V, so I replaced it.

Now I have one battery that performs well, but once charged drops in voltage to 0.2V below all others. It slowly discharges and takes it's "buddy" down with it unless I keep the car plugged in, and then the charger cycles on and off to keep these two fully charged. Today at work I will swap it out for my very last free spare battery and hope for the best.

I am not sure what I will do if (or when?) the next battery lays an egg because my free battery supply is dwindling. I hope that the batteries I murdered so far were faulty all along (which is likely because they were removed from trucks for a reason) and that they are not being prematurely murdered by my car. I guess I will know soon enough.

If these Paccar Dual-Purpose batteries cannot handle duty in my electric car I may start replacing them two at a time with new deep cycle batteries from Interstate Battery. Through my work I get a smoking deal at Interstate and I would have 30 month warranty that way. But I wonder if I should replace dead ones with new as they fail or just pull the pin and drop $1000 on a new pack so I can just forget about it and be happy....

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