Zenn DC Controller(or parts)AndChevyBoltPack+gauge questions

MitchJi

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Jun 2, 2008
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Marin County California
I hired Brian at Thunderstruck EV to install two Chevy Volt 22S modules (he trimmed two cells off of two 12S modules to get 22S) in parallel (90AH) into my Zenn NEV.

That configuration should have (22 x 4.1v x 90Ah) 90.2 x 90 = 80.18kWh, which should give a range of about 50 miles. But 84 volts is all we can get out of the battery pack before we get an over voltage error from the controller (a Sepex GE IC3645SR7A353E1).

Which means that we can only charge the cells to 3.81 volts which is limiting the range to about 20 miles.
Our choices are (I think):
1. find another sepex controller that can handle the higher voltage. If it's simple to install, and cheap that's the preferred solution.
2. flashing the controller so that would allow 90+ volts. I was told that this is impossible (?).
3. Use only 20S of the cells. We would just leave them in and by wiring around four groups of cells (I hate to waste the cells, but that might be the only cheap option?).

Two related questions are:

1. What's a good charge voltage to use? Is 4.1v too high for good cell life?
I believe that the Volt charges to about 390V at full and discharges to around 330V at empty - or about 4.06V / cell when full and 3.44V / cell when empty.

There is a 9ah difference between 4.06v and 4.17v. That's 20% of the pack. From what I've heard, the Volt cells have a lot of capacity near the top of the charge. This test supports that.
2. What's the easiest to install and configure, and accurate, gauge to measure the remaining range?
 
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