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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...
MEXICOWANDERER's avatar
MEXICOWANDERER
Explorer
Oct 28, 2016
You MUST use a genuine proved accurate hydrometer for this guesstimate.

For a ROUGH idea use a twelve volt 100-watt light bulb from an auto parts store.

It will consume ROUGHLY 8.1 amperes.

Connect it to a fully charged 100 amp hour battery.

Turn on the bulb.

Six hours later switch off the bulb.

Wait two hours. This is crucial

Then dip all six cells.

Consult a specific gravity to state of charge graph for your battery

Well?

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