Your car battery voltage range can vary, depending on a variety of factors. Much depends on the health of the automobile battery and all of its cells, the actual chemistry that creates and holds the electricity in storage, and the battery’s state of charge. For starters, most common 12-volt wet-cell or lead-acid batteries are made from six individual storage cells. Each cell of the storage battery supplies around 2.1 volts of electricity, as long as it is functioning correctly.
So, when we do the arithmetic, 6 cells x 2.1 volts each = 12.6 volts in total. And that is a good, healthy voltage for a 12v automobile battery to have.
Car battery voltage range
Now while car and automobile batteries are nominally twelve-volt batteries, their actual measured voltage can be anywhere from just under 11 volts, up to around 13.8 volts; and perhaps slightly higher. The higher voltages can be measured when the vehicle’s motor is running fast and the automobile’s alternator is busy charging the battery at a high rate of charge.
On the other hand, a car battery voltage of less than 11 volts is a very bad sign. At the very least it means the battery is already badly discharged and should not have any more power drained from it. This will happen if you do something like absent-mindedly parking your car with the headlights still on. Over several hours, such as overnight or while you are at work, this will empty all power from the battery and leave you with a flat battery.
A flat or discharged battery should be given a recharge immediately for, if this is not done quickly, the battery may never recover fully. If you apply a volt meter to the battery terminals you will probably see about eleven-point-something volts, instead of the normal twelve-point-something volts. You have probably discovered that the battery doesn’t have enough power to crank over your engine anyhow. You will need to charge up the battery first. And in the meantime, you will have to get a jump-start from somebody to get your car’s engine running once again.
Any voltage below 10.5 volts from your flat battery indicates that one or more of the individual battery cells has died. That means it is time to throw out the old defective battery and buy yourself a replacement auto battery.