Minimum voltage reading?

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Minimum voltage reading?

Postby Mountainhwy4 » Mon Apr 19, 2021 6:53 pm

So I’ve looked at the battery FAQ site and I didn’t see any definitive answer to what the minimum voltage for a 12V AGM battery should read. I’ve been drawing it down to around 11V before charging it back up (I’ve only charged it 3 times), can/should I be taking it lower?
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Re: Minimum voltage reading?

Postby saltydawg » Mon Apr 19, 2021 8:32 pm

You are going to kill the battery very quickly doing that, in fact you probably have already damaged it, but not to the point its trash. You probably have taken a couple % of the capacity from the battery in those few discharges. 12.3 is the lowest you should take it, and thats a 50% discharge, but some say 70 to 80% is okay for agm.

There are some who say the total amp hours you will get out of it is the same at a 70% discharge as a 50%. ie 500 cycles pulling 50 amps gives you 25,000 ah's or 70 amps at 350 cycles is also about 25,000 ah's ( based a 100 amp battery ). You should also not use volts as the level of discharge, as it will read higher when fresh off the charger, and it will recover some after a load is taken off of it. Ideally it should rest for 12 to 24 hours to give a true state of charge based on voltage. Buy the ali battery monitor from amazon for 42 bucks, and see the actual discharge in %, not voltage.

11 volts is is a 100 % discharge.

https://www.energymatters.com.au/components/battery-voltage-discharge/
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Re: Minimum voltage reading?

Postby friz » Mon Apr 19, 2021 8:47 pm

I never pull mine below 12v.

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Re: Minimum voltage reading?

Postby RJ Howell » Tue Apr 20, 2021 7:25 am

I also agree not to bring it lower than 12.3v, heck my lithium's I don't go below 13v..

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