Deciding on Battery Replacement
Hello all, my question is: What are the best way(s) to tell if an AGM battery has lost enough of its capacity that it should be replaced? (And if it's anything complicated I will probably need a...
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The 20 hr rate on a 54 AH battery is 2.7 amps. So a full battery ought to be at 50% SOC after 10 hours at 2.7 amps.
So do them one at a time (in case some are good and others not so good while in your parallel bank)
Find the voltage vs SOC table for those AGMs. EG, mine are 13v full and 12.4v at 50%. YMMV so find the right numbers.
Charge each one to full, run a 3 amp load such as a typical RV two bulb lamp and check its voltage after 5 hours. (Disconnect the load and wait half an hour for the voltage to bounce back.) If the battery is as new, it should be about 75% SOC.
If it is lower than that, you know the battery is not like new. Keep going, spot checking each hour from now on. Say it gets to your 50% voltage at 7 hours.
That means your battery is only 70% good as new. 8 hours is 80% and so on.
Now it is up to you how much capacity remaining is enough.
The 20 hr rate on a 54 AH battery is 2.7 amps. So a full battery ought to be at 50% SOC after 10 hours at 2.7 amps.
So do them one at a time (in case some are good and others not so good while in your parallel bank)
Find the voltage vs SOC table for those AGMs. EG, mine are 13v full and 12.4v at 50%. YMMV so find the right numbers.
Charge each one to full, run a 3 amp load such as a typical RV two bulb lamp and check its voltage after 5 hours. (Disconnect the load and wait half an hour for the voltage to bounce back.) If the battery is as new, it should be about 75% SOC.
If it is lower than that, you know the battery is not like new. Keep going, spot checking each hour from now on. Say it gets to your 50% voltage at 7 hours.
That means your battery is only 70% good as new. 8 hours is 80% and so on.
Now it is up to you how much capacity remaining is enough.
