On a car battery, what is a good charge/voltage?

Question

I took my car in for an oil change and they gave me a battery test. Their results were that the charge on my car battery was low, about 12.46 voltage. So I took my car to Les Schwab and they said that it was fine. I asked them what the voltage was and they said about 12.1 voltage. Then I tried looking online and from what I've read, anything around 12.1 is about 25-30% charged. I'm a bit confused. So can someone explain to me what a good charge/voltage is on most car batteries?

Answer 1

There seems to be some confusion here, A fully charged (90-100% state of charge) 12volt battery is 12.60 volts! Each cell produces 2.1 volts and there are 6 cells in a standard battery. The best way to check a battery is not by the "Static" voltage (because the battery could have a 1.75-2.50 surface charge) the Specific Gravity must be 1.265 (I like to see 1.275) and a fully discharged battery would show 1.120 or lower until it is just water. Also load testing a battery @ a specified load for 15 seconds and voltage should not drop below 10.25 volts!

Answer 2

That's fine if they only looked at the battery. With the engine running, the voltage should kick up to almost 14 volts as the alternator charges the battery. The alternator only puts out this extra voltage when the battery needs to be charged back up, and that is not constantly. If you aren't having problems with the car, just drive it. Those guys are just worrying you to make you buy a new battery.

Answer 3

The voltage when you shut off your car should settle down to 12.6 or so. 12.1 is low but if your doors are open, that will make a difference. I go by starting it up and measuring the charging voltage. If its over 14.9, you have a low battery. If you in doubt, or if its a couple years old (or older) replace it. It cost more for a tow than a new battery.

Answer 4

i assume you mean what your batt volt reads with eng not running.



your alternator charges at about 14.0 volts all the time .



so just after you turn off your car the batt will read higher .



anyway , that is not how you test a batt.



but the oil change place must have been trying to sell you something.



because 12.46 v would be HIGH not low for resting 12 volt batt.



they were LYING !! to you Girl ;(



not sure what you were looking at on the net that said 12.1 is 25% charged , because that is not correct at all . You have a 12 volt batt.



low would be more like 11.2 volts



EDIt ; hahaha



well , james and don are clueless and have no idea what they are blabbering about so you can just ignore them.



and mastec is correct ,



but he likes to impress himself by , blabbering a bunch of stuff to confuse you and think it makes him feel smart ; , hahahaha.