Posted: 8/1/2016 9:39:18 PM EDT
| I have two identical 80ah AGM batteries. I've been switching the one charger I have between the two every week or so. One battery still charges to 100%, the other gets stuck at 75% now. Should I discharge it and start over or have I ruined an expensive battery? I was trying to get them charged to the same state so I could hook them up in parallel as suggested in the other thread. |
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Sounds like one of the cells might be dead.
As a general rule don't discharge AGMs below 50%, and definitely not below 80%, depth of discharge. I'd put a mild load on the both, my bet is the 75% charge one folds like a lawnchair under any reasonable load, which would confirm a bad cell. |
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Quoted:
I'll try to check them tonight. I am surprised that they discharge so quickly just sitting there disconnected. If you have access to the individual cells/electrolyte, you can dip your VM probes in the electrolyte with the other lead on the ground terminal and determine if in fact you have a bad cell or two. If you see a relatively even increase across each cell, I'd get a desulphator and try to revive it. I have yet to fail to revive a 12v battery to new at didn't have a bad cell. |
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Just my two cents, take it for what you paid for it: I've done a bit of screwing around with some fancy high-dollar AGM batteries (actually picking up 4 for a member here on Saturday). Anyways, I've done quite a bit of research and experimenting on the topic. What I've learned:
Any more questions let me know, and I will answer to the best of my knowledge. |