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Old 10-03-2009, 05:28 PM   #110 (permalink)
mcmahon.craig
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Quote:
Originally Posted by JasonG View Post
Sorry to rain on your parade but you will only have ~75AH.
Series brings the voltage up but not the AH. That will be an average of all the batteries. To bring the AH up you will need more batts to parallel with the ones you have.
No, it will be the LOWEST of all the batteries. In fact, it's the worst CELL.

Say you have two batteries connected in series. One can provide 20Ah to an EPV to 1.7Vpc, and the other only 15Ah to the same point.

When you discharge the batteries, the cell voltage will obviously drop. At 15Ah the voltage on the 15Ah battery will be 1.7Vpc (about 10V), but the 20Ah will be more like 11.5 volts.

At this point, if you discharge the batteries further, the lower capacity battery WILL be damaged. If you attempt to retrieve the last 5Ah out of the good battery, you will probably reverse a cell in the bad one and destroy it.

If you're going to use mismatched batteries, please at least use one of these to avoid exploding batteries. You could also perform a measured discharge (using a known load, like a headlight) to 10.5V to ensure your batteries are at least somewhat matched.
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Last edited by mcmahon.craig; 10-03-2009 at 05:29 PM.. Reason: Modified Hyperlink
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