See Figures 1, 2, 3 and 4
All vehicles were originally equipped with a maintenance free battery as standard equipment, eliminating the need for fluid level checks and the possibility of checking specific gravity using a hand held tester. Nevertheless, the battery does require some attention.
At least once a year, the battery terminals and the cable clamps should be cleaned. Remove the post clamps or side terminal bolts and the cables, negative cable first. 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. 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 side terminal clamps and terminals.
Before installing the cables, loosen the battery hold-down clamp, 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 given a coat of anti-rust paint. Replace the battery and tighten the hold-down clamp securely but be careful not to overtighten, which will crack the battery case.
Surface coatings on battery cases can actually conduct electricity which will cause a slight voltage drain, so make sure the battery case is clean. Batteries can be cleaned using a paste made from a mixture of baking soda and water. Spread the paste on any corrosion, wait a few minutes, and rinse with water. Finish the job by cleaning metal parts with a wire brush.
After the clamps and terminals are clean, reinstall the cables, negative cable last. Give the clamps and terminals a thin external coat of nonmetallic grease after installation, to retard corrosion.
Check the cables at the same time that the terminals are cleaned. If a cable insulation is cracked, broken or the ends are frayed, it should be replaced with a new one of the same length and gauge.
TESTING THE MAINTENANCE FREE BATTERY
See Figure 5
Maintenance free batteries, do not require normal attention as far as fluid level checks are concerned. However, the terminals require periodic cleaning, which should be performed at least once a year.
The sealed top battery cannot be checked for charge by checking the specific gravity using a hand-held hydrometer since there is no provision for access to the electrolyte. Instead, the built-in hydrometer must be used in order to determine the current state of charge:
- If the indicator eye on top of the battery is dark, the battery contains sufficient fluid. If the eye is light, the electrolyte fluid is too low and the battery must be replaced.
- If a green dot appears in the middle of the dark eye, the battery is sufficiently charged. Proceed to Step 4. If no green dot is visible, charge the battery as in Step 3.
- Charge the battery referring according to the proper charging rate (amps) for the necessary time span and rate of charge.
- 75 amps - 40 min
- 50 amps - 1 hr
- 25 amps - 2 hr
- 10 amps - 5 hr
It may be necessary to tip the battery from side to side to get the green dot to appear after charging.
- Connect a battery load tester and a voltmeter across the battery terminals (the battery cables should be disconnected from the battery). Apply a 300 amp load to the battery for 15 seconds to remove the surface charge. Remove the load.
- Wait 15 seconds to allow the battery to recover. Apply the appropriate test load, as specified on the battery label, for 15 seconds while reading the voltage, then disconnect the load. Some appropriate loads on original batteries are:
- 75-60 - 260 amps
- 78A-72 - 300 amps
- 83-50 - 150 amps
- 83-60 - 180 amps
- 85A-60 - 170 amps
- 87A-60 - 230 amps
- 89A-60 - 270 amps
- 1981103 - 200 amps
- 1981104 - 250 amps
- 1981105 - 270 amps
- 1981577 - 260 amps
- Check the results against the appropriate minimum voltage based on the battery temperature. If the battery voltage is at or above the specification for the temperature listed, the battery is good. If the voltage falls below specification, the battery should be replaced.
- 70°F or above - 9.6 volts
- 60°F - 9.5 volts