Battery Facts and how to test them.

Things to look for in a battery:

1.Damage to the case or terminals.
2.Leaks or the top of the battery being wet
3.Is there enough acid in the battery
4.Voltage level after sitting for at least 8 hours
5.Amount of current the battery can produce.
6.Corrosion on the terminals.
7.Specific gravity.
8.Battery getting hot when car running.

If the top of the battery is wet it may not be able to accept proper charge (Bad cell) or has been overcharged. (Too much voltage) It may also have too much acid in it.

There should be enough acid to at least cover the plates. Usually about 3/8" above them. Don't overfill or they will bubble out of the vents when charging and make a nasty mess. (Sealed batteries can not be checked for acid level)

A battery should read between 12.7 and 13.0 after sitting for at least 8 hours. If you test right after shutting the car off or just removing a charger, it will be significantly higher. If its lower than that, it either needs to be charged or has a cell or two that are not it too good of shape. Make sure you don't have any load on the battery when making this test, like key being on or doors open. This will put a load on the battery and not give you the reading you need.

When load testing a battery for CCA's, it should be able to produce half the CCA rating in amps and the voltage should not fall below 10.5.
A 1000 CCA battery should be able to do 500 amps for 15 seconds and maintain no less than 10.5 volts. If its less, charge the battery and have it tested again or get a new one.
Bat Caps are the same way, the Bat Cap 400 (400 CCA) should be able to produce 200 amps for 8 seconds....not the standard 15 seconds. Not a good comparison to a standard battery because they don't rate them like everyone else.
Never make a battery produce more than half of its CCA rating.

If the terminals are corroded, clean them and you can get treated pads that go under the terminal from just about anywhere that impede the corrosion process. Usually one red and one green one. Sealed batteries usually don't have this problem.

If you have a hydrometer, you can check the state of charge with it. The value should be 1.225 or higher. If its less than that, charge them overnight.

If the battery is hot when charging, your either charging it too fast or have a bad cell. Either charge it with a lower amperage or replace the battery. A battery will get hot when charging but don't let it get too hot.

Its not a good idea to load test batteries right after giving them a high current charge like from a charger. The reversal of electron flow from going into the battery and then out may cause the battery to explode. Not a pretty sight.

Here is a general guideline of charging currents/length of time...(assuming 50% discharge)

Example:
550-875 CCA Starting type battery. (One battery. two batteries would be double)

2 amp charge=35-55 hours
10 amp charge=7-11 hours
30 amp charge=2-7 hours
40 amp charge=2-3 hours
60 amp charge=1-2 hours

If you have a bank of batteries, multiply the number of batteries by the charging amperage or length of charge.