a friend of mine at the marina just gifted me three huge agm batteries.

submitted by ababydog from self.whatever

they are almost brand new.

new, they cost almost $1,200 each.

not bad for a day's work.

im gonna put them into my boat for my 12volt system.

these batteries are 150 pounds each.

ALL THREE OF THEM HOLD A CHARGE OF APPROX 12.8 TO 13.2 SITTING IDLE, WHICH IS THE EQUIVALENT OF BRAND NEW.

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[–]aqop 1 insightful - 2 fun1 insightful - 1 fun2 insightful - 2 fun -  (6 children)

damm. i put one of them on a slow charge and then removed the charger and twenty minutes later it is holding a voltage of 12.99 volts.

i am gonna offer to give these back to the guy, cuz he thought they were not good, boy was he wrong.

[–]Zapped 1 insightful - 2 fun1 insightful - 1 fun2 insightful - 2 fun -  (5 children)

Have you tested the batteries under load?

[–]aqop 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (3 children)

yes, i have a 12 volt spotlight that i run on it..

[–]iamonlyoneman 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (0 children)

That is not a proper test. Refer to page 19 for how to load test large batteries https://dekabatteries.com/assets/base/0656.pdf

Also read the rest of it because if you have big batteries you should really know most of that stuff!

[–]Zapped 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (1 child)

I'm not sure if the spotlight would be enough for a proper test. You can charge them and take them to an auto parts store and they will load test it for free, or you can but a load tester and do it yourself. They run form $50-$100 but you can find them at Harbor Freight for around $20.

[–]aqop 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (0 children)

i just put a digital voltmeter on it and i know how a "bad" battery behaves... and i know how a fresh battery behaves.. if the battery is bad and i put a heavy load on it and it drops low maybe below 12 volts, it aint good.

[–]iamonlyoneman 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (0 children)

Nice.