Read the Disclaimer . Automotive batteries are 12 volt negative ground. The amperage ratings on batteries will very depending on the amount of power accessories your car has. If your car has a small 4 cylinder motor with no power accessories, your battery does not need a lot of reserve amperage. On the other hand, if your car has a big V-8 motor and all the power options you can get, your battery will need a lot more amperage in reserve.
Amperage is the amount of current required to overcome the resistance of an electrical item.
Each cell has positive and negative plates in it, separated by a cardboard like material so that the plates do not touch together. If this material breaks down and the plates touch it can short out your battery. This can happen at any time with out any warning. As the battery gets run down it needs to be recharged by the alternator. Alternators like batteries, will very in amperage output.