12 volt battery

What reading should I get from a battery sitting on the bench ? I believe it is fully charged. I'm thinking I shouls get a reading of around
12.5 Volts.

12.6 in a perfect world

12.6 if sitting for 2-3 weeks. 12.7 if just off a 10 amp or more charger. Jim

12.5 is a tad bit low but for the common house hold VOM that could well be the voltmeter being off. 12.6-12.7 is a full charged battery but again that is with a calibrated meter which your not likely to own

Michael actually the voltage of a fully charged lead acid battery AT REST AND STABILIZED depends on the temperature. Here are the voltages and specific gravity at different temperatures:

Temperature: 57 degrees Fahrenheit

Percent Hydrometer Unloaded
charge reading voltage
100 1.258 12.59
75 1.203 12.26
50 1.153 11.96
25 1.113 11.72
0 1.093 11.60


Temperature: 67 degrees Fahrenheit

Percent Hydrometer Unloaded
charge reading voltage
100 1.262 12.61
75 1.207 12.28
50 1.157 11.98
25 1.117 11.74
0 1.097 11.62


Temperature: 77 degrees Fahrenheit

Percent Hydrometer Unloaded
charge reading voltage
100 1.265 12.63
75 1.210 12.30
50 1.160 12.00
25 1.120 11.76
0 1.100 11.64


Temperature: 87 degrees Fahrenheit

Percent Hydrometer Unloaded
charge reading voltage
100 1.268 12.65
75 1.213 12.32
50 1.163 12.02
25 1.123 11.78
0 1.103 11.66

John T

Sorry, I copied and pasted the chart but it doesn't come out right when I press submit grrrrrrrrrrrrr so I will try this:

Full charged voltages at X temperature are as follows"

57 Degrees 12.59 Volts,,,,,67 Degrees 12.61 Volts,,,,,,,,77 Degreees 12.63,,,,,,,,,,87 Degrees 12.65

Thats all I have time for lol

John T

Temperature: 57 degrees Fahrenheit

Percent Hydrometer Unloaded
charge reading voltage
100 1.258 12.59
75 1.203 12.26
50 1.153 11.96
25 1.113 11.72
0 1.093 11.60


Temperature: 67 degrees Fahrenheit

Percent Hydrometer Unloaded
charge reading voltage

100 1.262 12.61
75 1.207 12.28
50 1.157 11.98
25 1.117 11.74
0 1.097 11.62


Temperature: 77 degrees Fahrenheit

Percent Hydrometer Unloaded
charge reading voltage

100 1.265 12.63
75 1.210 12.30
50 1.160 12.00
25 1.120 11.76
0 1.100 11.64


Temperature: 87 degrees Fahrenheit

Percent Hydrometer Unloaded
charge reading voltage


100 1.268 12.65
75 1.213 12.32
50 1.163 12.02
25 1.123 11.78
0 1.103 11.66

Every 3 months my Fluke VOMs, scopes, megger,amp clamps and ground tester are calibrated, as well as my torque wrenches,mics calipers,dial bore gauge and dial indicators.

Ah but that is not the common norm for most people

u are good. the average person wont pay attention to .1 or .2 of a volt difference. and if its reading that it will crank your tractor. ideal is to load test before using a battery. volts can fool you.