http://www.landiss.com/battery.htm

Actually they are at 12 volts when they are stagnant but the alternator useually keeps the car running around 14.4 volts give or take a little bit based on the size of the alternator

Like i ain't got enough problems.
Now i'll stay awake half the night worrying about my frigin car battery.
Thanks P2.

Actually. A standard car battery has six cells that are 2.1 volts each for a total of 12.6 volts.

Maybe they used to be 12 volts?

x2

batteries take a lot of abuse. the higher temps under the hood in the summer are more damaging than the colder temps in the winter. optimum battery temp is 70F like most electronic components. extreme cold temps can freeze lead-acid batteries making them not conduct very well and split the plastic cases on them so the fluid leaks out making it less conductive. as a battery ages and cycles through charge and discharge some of the lead oxidizing and hard sulfer deposit that occurs in the battery starts to remain on the plates making it less conductive and less able to store a charge. you can de-sulfate or reverse pulse charge the battery to loosen up and dissolve some of that lead oxide/sulfer to help lengthen the life of the battery. if the plate connections open up you will get a open cell condition and the battery will no longer charge to 12.6V. The plates can be covered so severly in oxidation that they fuse together creating a shorted cell condition. this also lessens the batteries ability to take/store a charge. as you draw current from your battery the voltage drops and can sometimes drop to a low enough voltage to affect devices that run on 12V. 10.5V is usually what 12.0 things are designed to run at as a minimum. most digitally active circuits are designed to run on 5Vdcc down to 3.5Vdcc or so. The alternator/generator in your car charges at 14.4V as to allow a higher voltage than the battery so the charge current will flow into the battery. The limiting factor of current from an alternator is the rectifier diodes. They along with the size/type/number of windings/rpm limit the amount of current that can be produced from the alternator. Most cars have a stock 75-115A rating. more useless stuff i know.
Cold Cranking Amps is a rating used in the battery industry to define a battery's ability to start an engine in cold temperatures. The rating is the number of amps a new, fully charged battery can deliver at 0° Farenheit for 30 seconds, while maintaining a voltage of at least 7.2 volts, for a 12 volt battery. The higher the CCA rating, the greater the starting power of the battery. Batteries loose this CCA ability over the life of the battery. Try starting your car in >5sec bursts. This helps you get the most cranking amps possible each time by allowing the voltage to be higher in short pulses of use.

Did anyone actually READ the link?

prob not,

yep.