Generally speaking, a battery of 525 CCA will probably start and run a Street Stock-type of car for the night without an alternator. This is with the understanding your engine starts easily. This won't necessarily be true in other classes with high compression engines. Check a battery in a car similar to yours at the end of a night's worth of racing. Use a good voltmeter. It should be at least 12.00 volts. If so, then this is an adequate size battery for your use. If you use an alternator, a slightly smaller battery may be used. Here you will be using up more "Reserve Capacity" (RC) to start the engine, but the alternator will soon be recharging the battery to a point of maintaining proper voltage for the ignition.

SCR: What if you're not using a charging system?
Kimbrough: The RC of a battery becomes important. Most electronic ignitions need more than 10.5 volts to operate properly. Most batteries don't have the RC on the label. However, if you look in the dealer's book, the RC is listed for all batteries. Remember, the drain of the starter will use up some of this RC each time the engine is started. A 200-amp load imposed by the starter is not uncommon. If the engine starts in 3 seconds, good. If it sometimes takes 30 seconds of winding the starter and heating the cables to get your engine going, this is a sign you may need the insurance of a greater capacity battery.

It is very important for the starter to have adequate power going to it during the starting process. At the instant of electrical contact between the battery and the starter, the battery voltage drops drastically for about 11/43 of a second or so, then it rebounds. When battery voltage is in a low state of charge, or the battery is too small for the job, it does not rebound as it should. Thus, low voltage overheats the starter and the engine turns slowly. Three things can happen here. First, the engine won't start. Second, another larger battery may be needed. Third, the starter itself may be damaged by low voltage and heat. So the battery needed in your race car must have the CCA capacity to start your engine and the RC to maintain ignition voltage. We have made great advances in vibration/impact resistance over the years. The polyethylene sleeve, among other technical advances, has helped automotive batteries to live well in racing applications.

SCR: What about batteries that appear to have dry cells, the ones that look like a battery pack?
Kimbrough: These are especially good when extreme vibration and impact resistance are a prime consideration. They are referred to as Optima AGM batteries. AGM stands for absorbed glass mat. In these batteries each cell (6 in a 12v. battery) is spiral wound with layers of glass mat and lead grid. The acid is absorbed by the glass mat. When tightly wound, there is virtually no internal place in the battery where movement can occur. As such, this type of battery can resist more impact than a conventional battery and still keep functioning. Another factor for race car use is that the AGM can be mounted in any position. While it is lighter, it is also priced somewhat higher than a conventional battery.

SCR: Let's talk about connections and corrosion. This seems to be a never ending problem. What is your advice?
Kimbrough: We need to start by getting all the battery connections clean. This can be done several ways. There are mechanical cleaners that scrape or wire brush the inside and outside of the terminals. A pocketknife should not be used for this purpose. The mechanical cleaners leave a surface in the same shape, round and tapered, as originally made. A soda wash with a small brush can be used to remove all the corrosion. Common baking soda, mixed 50/50 with water, will do. Although it may seem to do so, your favorite cola doesn't really do that good a job. The key with any terminal connection is to get it completely clean.