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profdant139's avatar
profdant139
Explorer II
Oct 27, 2016

Is there a real-world test of a battery's true capacity?

My two group 31 batteries are rated at 110 amp hours -- and I never discharge them past 12.1 volts, or 50 percent state of charge. So that means, I think, that I should be able to get 55 amp hours ou...
KD4UPL's avatar
KD4UPL
Explorer II
Oct 27, 2016
Hook up some 12v bulbs totaling around 5 amps. The standard time frame for listing AH rating is 20 hours so your batteries should support 5.5 amps for 20 hours until they drop to 10.5 volts.
Connect your load of as close to 5.5 amps as you can get and check the battery voltage every 15 minutes or so. See how long it takes to drop to 10.5.
It's that simple.

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