Cold Cranking Amps are a rating system developed by the Battery Council International, to state the power a battery has. The cold cranking rating is how long a battery can put out enough power to start your car for 30 seconds at zero degrees Fahrenheit. For some people, this is the gold standard of how to tell if a battery is good. It is true that it is a measure of strength and it is important to know how strong your battery is, and there are other benefits.
It is also a good way to compare batteries, and since it is done by the battery council, there is no bias toward a single company. There are some battery companies that come up with things like hot cranking amps and other things. The problem is they are all self-defined, and that makes it hard to compare because you don’t know what the criteria are. With cold cranking amps, there is no such ambiguity.
If you live in a warm climate that rarely gets to freezing or below, you may not think it is relevant to know how well it will do at zero degrees or below. But it is relevant because it is a legitimate way to compare batteries. So, even if you may never need to start your car when it is that cold, at least you know how to compare batteries in a store. Another measure is just Cranking amps or marine cranking amps as it is called, which just, measures the same thing at a slightly warmer temperature.
It is important to have at least what your owners manual recommends, which is what your car or truck was designed for. It is debatable as to whether you need more than that if you have not made significant modifications.
The number also means if you have to replace your alternator, and are looking for an aftermarket replacement alternator. The replacement car alternator needs to have adequate power, or the power it was designed to manage. Not matching that up with your battery can shorten the life of both. If you have made modifications, installed a powerful sound system, for instance, you might need a high output alternator. You may also consider a professional alternator, which is a refurbished alternator that returns it to manufacturers standards.
The cold cranking amps are necessary for comparison purposes, but the number also gives you an idea of the starting power of the battery. Alternators also have amp ratings, and they need to match that of your battery. Having more power than your alternator can handle just means wasted power and extra expense, so more is not always better. It may not hurt your car though. However, having less power than needed may damage your battery and alternator, and negatively impact the performance of your automobile.