Approximately how long should it take for a battery that has been run all day to recharge?

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Any Day Above Ground Is A Good Day

this would depend on the AH rating of your battery and the rate of charge from your charger.

In an ideal world you can compute that. Say you have a battery rated at 100 AH (amp hours) and the battery is depleted to 75%. If you have 5 amp charger, it would take 5 hours to charge it. (25 divided by 5). Unfortunately we don't live in an ideal world so that would be very approximate.

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Work is for people that don't know how to fish!

Bill H. PTC USN Ret
Chesapeake, Va

You can roughly figure the charging cycle is about 50% efficient, so it's roughly double what it would be in the perfect world. Much of what could be charging the battery is lost as heat.

I use a battery tester (shows % of discharge) ... then hook up my Shumacher Deep Cycle 10amp charger, and set it to charge about 5hrs per each 25% of discharge.
It's not an "automatic" type of charger, but I think it does reduce the amp output as the battery charges up.

After charging ... check the water levels and add distilled water, if needed to fill the cylinders back up to the bottom of the holes (if you have a lead acid battery).

My "battery tester" is a Firstmate (model 12-3) and came with a formula for determining charge time. Canepole might be able to figure it out, for accuracy

It says :
Charging time = battery amp hours x (100 minus reading in %) x .01 .... divided by 0.7 x charger output amps

SO ... with a 125AH battery, reading 50% discharged, and using a 10amp charger .... it would take about 9hrs.

That's 125 x 50 x 0.01 = 62.5 ... divided by 7 = 8.9

(on my Everstart Maxx-29 ... at 50% discharge ... it would take 14hrs)

... cp

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