Loose, dirty, or corroded battery terminals are a major cause of ""no-start." Every 3 months or so, remove the battery terminals and clean them, giving them a light coating of petroleum jelly when you are finished. This will help to retard corrosion.
Check the battery cables for signs of wear or chafing and replace any cable or terminal that looks marginal. Battery terminals can be easily cleaned and inexpensive terminal cleaning tools are an excellent investment that will pay for themselves many times over. They can usually be purchased from any well-equipped auto store or parts department. The accumulated white power and corrosion can be cleaned from the top of the battery with an old toothbrush and a solution of baking soda and water.
Unless you have a maintenance-free battery, check the electrolyte level (see Battery under Fluid Level Checks in this section) and check the specific gravity of each cell. Be sure that the vent holes in each cell cap are not blocked by grease or dirt. The vent holes allow hydrogen gas, formed by the chemical reaction in the battery, to escape safely.
Two types of batteries are used: Standard and Maintenance-Free. Both types are equipped with a Charge-Test Indicator, which is actually a miniature hydrometer built into the filler cap of the cell. The indicator will show green if the battery is above 75-80% charged, or dark if the battery needs recharging. Light yellow indicates the battery may be in need of water or replacement.
For standard batteries, check the level of the electrolyte every 2 months; more often on long trips or in extremely hot weather. If necessary add mineral free water to the bottom of the filler well.
At least once a year, check the specific gravity of a standard battery.
CABLES AND CLAMPS
Once a year, the battery terminals and the cable clamps should be cleaned. Loosen the clamps and remove the cables, negative cable first. On batteries with posts on top, the use of a puller specially made for the purpose is recommended. These are inexpensive, and often available in auto parts stores. Side terminal battery cables are secured with a bolt.
Clean the cable clamps and the battery terminals with a wire brush until all corrosion, grease, etc..., is removed and the metal is shiny, It is especially important to clean the inside of the clamp thoroughly, since a small deposit of foreign material or oxidation will prevent a sound electrical connection and inhibit either starting or charging. Special tools are available for cleaning these parts, one type for conventional batteries and another type for side terminal batteries.
Before installing the cables, loosen the battery hold-down clamp or strap, remove the battery and check the battery tray. Clear it of any debris, and check it for soundness. Rust should be wire brushed away, and the metal should be given a coat of anti-rust paint. Install the battery and tighten the hold-down clamp or strap securely, but be careful not to overtighten, which will crack the battery case.
After the clamps and terminals are clean, reinstall the cables, negative cable last; do not hammer on the clamps to install. Tighten the clamps securely, but do not distort them. Give the clamps and terminals a thin external coat of grease after installation, to retard corrosion.
Check the cables at the same time that the terminals are cleaned. If the insulation is cracked or broken, or if the ends are frayed, the cable should be replaced with a new cable of the same length and gauge.
TESTING SPECIFIC GRAVITY
Except Maintenance-Free Batteries
At least once a year, check the specific gravity of the battery. It should be between 1.20-1.26 at room temperature. The specific gravity can be checked with the use of a hydrometer, an inexpensive instrument available from many sources, including auto parts stores. The automotive battery hydrometer has a squeeze bulb at one end and a nozzle at the other. Battery electrolyte is sucked into the the hydrometer until the float is lifted from its seat. The specific gravity is read by noting the position of the float. Generally, if after charging, the specific gravity between any two cells varies more than 50 points (.50), the battery is bad and should be replaced.
Most maintenance-free batteries are sealed, therefore it is not possible to check the specific gravity using a typical automotive hydrometer. Instead, the indicator built into the top of the case must be relied on to display any signs of battery deterioration. If the indicator is dark, the battery can be assumed to be OK. If the indicator is light, the specific gravity is low, and the battery should be charged or replaced. The indicator on some aftermarket batteries may vary, so be sure to check the instructions included with your battery if in doubt.
A true test of a battery's condition is the load test. It requires the use of a special carbon pile to simulate an electrical load on the battery. Normally, a battery is tested at half it's cold cranking amps rating or at three times the amp-hour rating for 15 seconds.
Generally, if after 15 seconds the battery voltage is not at 9.6 volts or more, the battery either needs to be recharged or replaced.
A battery should be charged at a slow rate to keep the plates inside from getting too hot. However if some maintenance-free batteries are allowed to discharge until they are almost ""dead", they may have to be charged at a high rate to bring them back to ""life". Always follow the battery charger manufacturer's instructions.
The cold power rating of a battery measures battery starting performance and provides an approximate relationship between battery size and engine size. The cold power rating of a replacement battery should match or exceed your engine size in cubic inches.