Car batteries pack a wallop. They are capable of producing an extraordinary amount of power – about 3 times as much as is required to run a clothes dryer – in a couple of seconds when you turn the ignition key.
Several hundred amps blast through the thick cables coming off your battery into your starter motor, which engages a ring gear that turns your motor and starts it.
Now let’s look at some of the numbers on the battery. There are essentially two that are important – its capacity and starting power.
Capacity it is a measure of how much charge the battery can produce before it is completely flat, and is measured in Amp Hours (Ah). A large battery for example may have a capacity of 60 Ah. This means plant it could theoretically deliver 60 amps for one hour, or one amp for 60 hours, or 2 amps for 30 hours and so on
But this is only a guide, and as you could never get anywhere near the theoretical amount. The reason for this is fact the voltage doesn’t have too drop much below 12 bolts and its essentially useless –an 11.5 V battery will not start your car.
The other number of interests is the Cold Cranking Amps. The CCA is a measure of how many amps the battery can deliver the moment you turn the key. For small cars this is normally 300 or 400 and is part for larger diesel motors it can be as high as 700 or 800 Amps.