12 volt batteries

I would expect 13-13.2 v but its not a fine art

At rest, with no ingoing or outgoing current, 12.7 to 12.8 is regarded to be fully charged.

I suggest having a look at this site

http://www.windsun.com/Batteries/Battery_FAQ.htm#Battery%20Voltages

You'll need to copy and paste it into your address bar; I'm not good with links.

Most places I have checked conform with the following chart:



Regards
David

Hi Lewjack

That question cannot be answered without knowing the type and roughly the temperature.

The 12.6 v shown in chart above is for normal lead acid at mid twenties which is a common measurement standard , becomes 12.8 for most AGMs

Robin Miller

Yeppers agree with Robin depends a lot the temp-batteries don't like being cold!!

Don't have on me the exact figures, but recently were told from the supplier of AGM deep cycle batteries,

12.8v = 100%
12.6v = 80%
12.4v = 60%
12.2v = 40%
12.0v = 20%

not recommended to go below 20% so don't go below 12.0v.

Barnesy

As you alluded to in your original post, but for the benefit of others as well ....
Those voltage figures are useless UNLESS the battery has been sitting for at least 12 and preferably 24 hours with no charge or discharge.
Cheers