Checking the condition of the battery by testing the state of charge.

VISUAL INSPECTION OF THE BATTERY. - Battery maintenance should always begin with a thorough visual inspection. Look for signs of corrosion on or around the battery, signs of leakage, a cracked case or top, missing caps, and loose or missing hold-down clamps.

CHECKING ELECTROLYTE LEVEL AND ADDING WATER. - On vent cap batteries, the electrolyte level can be checked by removing the caps. Some batteries have a fill ring which indicates the electrolyte level. The electrolyte should be even with the fill ring. If there is no fill ring, the electrolyte should be high enough to cover the tops of the plates. Some batteries have an electrolyte-level indicator (Delco Eye). This gives a color code visual indication of the electrolyte level, with black indicating that the level is okay and white meaning a low level.

If the electrolyte level in the battery is low, fill the cells to the correct level with DISTILLED WATER (purified water). Distilled water should be used because it does not contain the impurities found in tap water. Tap water contains many chemicals that reduce battery life. The chemicals contaminate the electrolyte and collect in the bottom of the battery case. If enough contaminates collect in the bottom of the case, the cell plates SHORT OUT, ruining the battery.

If water must be added at frequent intervals, the charging system may be overcharging the battery. A faulty charging system can force excessive current into the battery. Battery gassing can then remove water from the battery.

Maintenance-free batteries do NOT need periodic electrolyte service under normal conditions. It is designed to operate for long periods without loss of electrolyte.

CLEANING THE BATTERY AND TERMINALS. - If the top of the battery is dirty, using a stiff bristle brush, wash it down with a mixture of baking soda and water. This action will neutralize and remove the acid-dirt mixture. Be careful not to allow cleaning solution to enter the battery.

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. 2-8