To clean the terminals, remove the cables and inspect the terminal posts to see if they are deformed or broken. Clean the terminal posts and the inside surfaces of the cable clamps with a cleaning tool before replacing them on the terminal posts.

CAUTION
Do NOT use a scraper or knife to clean battery terminals. This action removes too much metal and can ruin the terminal connection.

When reinstalling the cables, coat the terminals with petroleum or white grease. This will keep acid fumes off the connections and keep them from corroding again. Tighten the terminals just enough to secure the connection. Overtightening will strip the cable bolt threads.

CHECKING BATTERY CONDITION.- When measuring battery charge, you check the condition of the electrolyte and the battery plates. As a battery becomes discharged, its electrolyte has a larger percentage of water. Thus the electrolyte of a discharged battery will have a lower specific gravity number than a fully charged battery. This rise and drop in specific gravity can be used to check the charge in a battery. There are several ways to check the state of charge of a battery.

Nonmaintenance-free batteries can have the state of charge checked with a hydrometer. The hydrometer tests specific gravity of the electrolyte. It is fast and simple to use. There are three types of hydrometers- the float type, the ball type, and needle type.

To use a FLOAT TYPE HYDROMETER, squeeze and hold the bulb. Then immerse the other end of the hydrometer in the electrolyte. Then release the bulb. This action will fill the hydrometer with electrolyte. Hold the hydrometer even with your line of sight and compare the numbers on the hydrometer with the top of the electrolyte.

Most float type hydrometers are NOT temperature correcting. However, the new models will have a built-in thermometer and a conversion chart that allow you to calculate the correct temperature.

The BALL TYPE HYDROMETER is becoming more popular because you do not have to use a temperature conversion chart. The balls allow for a change in temperature when submersed in electrolyte. This allows for any temperature offset.

To use a ball type hydrometer, draw electrolyte into the hydrometer with the rubber bulb at the top. Then note the number of balls floating in the electrolyte. Instructions on or with the hydrometer will tell you whether the battery is fully charged or discharged.

A NEEDLE TYPE HYDROMETER uses the same principles as the ball type. When electrolyte is drawn into the hydrometer, it causes the plastic needle to register specific gravity.

A fully charged battery should have a hydrometer reading of at least 1.265 or higher. If below 1.265, the battery needs to be recharged. or it may be defective. A discharged battery could be caused by the following:

Defective battery
Charging system problems
Starting system problems
Poor cable connections
Engine performance problems requiring excessive cranking time

Electrical problems drawing current out of the battery with the ignition OFF defective battery can be found by using a hydrometerto check each cell. If the specific gravity in any cell varies excessively from other cells (25 to 50 points), the battery is bad. Cells with low readings may be shorted. When all of the cells have equal specific gravity, even if they are low, the battery can usually be recharged.

On maintenance-free batteries a charge indicator eye shows the battery charge. The charge indicator changes color with levels of battery charge. For example, the indicator may be green with the battery fully charged. It may turn black when discharged or yellow when the battery needs to be replaced. If there is no charge indicator eye or when in doubt of its reliability, a voltmeter and ammeter or a load tester can also be used to determine battery condition quickly.