Batteries

[mclainfarm]

I have 4 6 volt Duracell batteries and trying to figure out the amp hour rating. The specs are
20 amp hour rate 215
5 amp hour rate 157
6 amp hour rate 156
Minutes at 25 amps 395
Minutes at 75 amps 105
Most batteries I read about state they are 100 amp hour batteries. What are mine? I’m trying to put together a solar system and need to know the size of my battery bank. Thanks for any help

[theoldwizard1]

The most commonly used rating is the 20 amp hour rating

"The amount of amp-hours (AH) a battery can deliver when discharged at a constant rate at 80°F (27°C) and maintain a voltage above 1.75 V/cell."

1.75 V/cell is past the typical amount you would discharge a battery to and, if done repeatedly, will shorten the life of the battery. For maximum life, do not discharge past 80% "state of charge" (SOC) which is 2.08V/cell. (12.48V for a 12V battery bank.)

Minutes at 25 amps (also referred to as Reserve Capacity) is another good reference, but not all manufactures publish this.

Yours are 215 amp-hours, typical for most 6V golf cart batteries. If they are wired 2 in series and then 2 in parallel, you have 430 amp hour @ 12V.

[wolfe10]

ON EDIT: Thanks to all who posted below who corrected my "BAD MATH". Concept correct, math not so much. Rather than leave questions, I will edit to supply, as others have done the correct answer: 430 AH @ 12 VDC.



The 20 hour rate is the most common rating.

So, each of your batteries is 215 AH @ 6 VDC. So each pair wired in SERIES is 215 AH @ 12 VDC.

Both pairs together (your battery bank) is 430 AH @ 12 VDC.