Battery check, maintenance and charging

Warning: Certain precautions must be followed when checking and servicing the battery. Hydrogen gas, which is highly flammable, is always present in the battery cells, so keep lighted tobacco and all other open flames and sparks away from the battery. The electrolyte inside the battery is actually dilute sulfuric acid, which will cause injury if splashed on your skin or in your eyes. It will also ruin clothes and painted surfaces. When removing the battery cables, always detach the negative cable first and hook it up last!

1. A routine preventive maintenance pro- gram for the battery in your vehicle is the only way to ensure quick and reliable starts. But before performing any battery maintenance, make sure that you have the proper equipment necessary to work safely around the battery (see illustration).

11.1 Tools and materials required for battery maintenance

1 Face shield/safety goggles — When removing corrosion with a brush, the acidic particles can easily fly up into your eyes
2 Rubber gloves — Another safety item to consider when servicing the battery; remember that’s acid inside the battery!
3 Battery terminal/ cable cleaner -This wire brush cleaning tool will remove all traces of corrosion from the battery and cable
4 Treated felt washers — Placing one of these on each terminal, directly under the cable end, will help prevent corrosion (be sure to get the correct type for side terminal batteries)
5 Baking soda — A solution of baking soda and water can be used to neutralize corrosion
6 Petroleum jelly — A layer of this on the battery terminal bolts will help prevent corrosion

Chevrolet Silverado  _

Note: Some models have an auxiliary battery in addition to the standard battery. All of the following care and maintenance should be applied to both batteries.

2. There are also several precautions that should be taken whenever battery mainstem Nance is performed. Before servicing the battery, always turn the engine and all accessories off and disconnect the cable from the negative terminal of the battery.

3. The battery produces hydrogen gas, which is both flammable and explosive. Never create a spark, smoke or light a match around the battery. Always charge the battery in a ventilated area.

4. Electrolyte contains poisonous and corrosive sulfuric acid. Do not allow it to get in your eyes, on your skin or on your clothes. Never ingest it. Wear protective safety glasses when working near the battery. Keep children away from the battery.

5. Note the external condition of the battery. If the positive terminal and cable clamp on your vehicle’s battery is equipped with a rubber protector, make sure that it’s not torn or damaged. It should completely cover the terminal. Look for any corroded or loose connections, cracks in the case or cover or loose hold-down clamps. Also check the entire length of each cable for cracks and frayed conductors (see illustration).

11.5 Typical battery cable problems

Chevrolet Silverado  _

6. If corrosion, which looks like white, fluffy deposits is evident, particularly around the terminals, the battery should be removed for cleaning. Loosen the cable bolts with a wrench, being careful to remove the ground cable first, and slide them off the terminals. Then disconnect the hold-down clamp bolt and nut, remove the clamp and lift the battery from the engine compartment.

7. Clean the cable ends thoroughly with a battery brush or a terminal cleaner and a solution of warm water and baking soda. Wash the terminals and the side of the battery case with the same solution but make sure that the solution doesn’t get into the battery. When cleaning the cables, terminals and battery case, wear safety goggles and rubber gloves to prevent any solution from coming in contact with your eyes or hands. Wear old clothes too — even diluted, sulfuric acid splashed onto clothes will burn holes in them. If the terminals have been corroded, clean them up with a terminal cleaner (see illustrations). Thoroughly wash all cleaned areas with plain water.

11.7a A tool like this one (available at auto parts stores) is used to clean the side- terminal type battery-cable contact area

Chevrolet Silverado  _  A tool like this one (available at auto parts stores) is used to clean the side- terminal type battery-cable contact area

11.7b Use the brush side of the tool to finish the job

Chevrolet Silverado  _  Use the brush side of the tool to finish the job

11.7c. Regardless of the type of tool used on the battery and cables, a clean, shiny surface should be the result

Chevrolet Silverado  _  Regardless of the type of tool used on the battery and cables, a clean, shiny surface should be the result

8. Make sure that the battery tray is in good condition and the hold-down clamp bolts are tight. If the battery is removed from the tray, make sure no parts remain in the bottom of the tray when the battery is reinstalled. When reinstalling the hold-down clamp bolts, do not overtighten them.

9. Any metal parts of the vehicle damaged by corrosion should be covered with a zinc-based primer, then painted.

10. Information on removing and installing the battery can be found in Chapter Engine electrical systems. Information on jump-starting can be found at the front of this manual. For more detailed battery checking procedures, refer to the Haynes Automotive Electrical Manual.


Warning: When batteries are being charged, hydrogen gas, which is very explosive and flammable, is produced. Do not smoke or allow open flames near a charging or a recently charged battery. Wear eye protection when near the battery during charging. Also, make sure the charger is unplugged before connecting or disconnecting the battery from the charger.

Note: The manufacturer recommends the battery be removed from the vehicle for charging because the gas that escapes during this procedure can damage the paint. Fast charging with the battery cables connected can result in damage to the electrical system.

11. Slow-rate charging is the best way to restore a battery that’s discharged to the point where it will not start the engine. It’s also a good way to maintain the battery charge in a vehicle that’s only driven a few miles between starts. Maintaining the battery charge is particularly important in the winter when the battery must work harder to start the engine and electrical accessories that drain the battery are in greater use.

12. It’s best to use a one- or two-amp battery charger (sometimes called a «trickle» charger). They are the safest and put the least strain on the battery. They are also the least expensive. For a faster charge, you can use a higher amperage charger, but don’t use one rated more than 1/10th the amp/hour rating of the battery. Rapid boost charges that claim to restore the power of the battery in one to two hours are hardest on the battery and can damage batteries not in good condition. This type of charging should only be used in emergency situations.

13. The average time necessary to charge a battery should be listed in the instructions that come with the charger. As a general rule, a trickle charger will charge a battery in 12 to 16 hours.

14. Remove all the cell caps (if equipped) and cover the holes with a clean cloth to prevent spattering electrolyte. Disconnect the negative battery cable and hook the battery charger cable clamps up to the battery posts (positive to positive, negative to negative), then plug in the charger. Make sure it is set at 12-volts if it has a selector switch.

15. If you’re using a charger with a rate higher than two amps, check the battery regularly during charging to make sure it doesn’t overheat. If you’re using a trickle charger, you can safely let the battery charge overnight after you’ve checked it regularly for the first couple of hours.

16. If the battery has removable cell caps, measure the specific gravity with a hydrometer every hour during the last few hours of the charging cycle. Hydrometers are available inexpensively from auto parts stores — follow the instructions that come with the hydrometer. Consider the battery charged when there’s no change in the specific gravity reading for two hours and the electrolyte in the cells is gassing (bubbling) freely. The specific gravity reading from each cell should be very close to the others. If not, the battery probably has a bad cell(s).

17. Some batteries with sealed tops have built-in hydrometers on the top that indicate the state of charge by the color displayed in the hydrometer window. Normally, a bright-colored hydrometer indicates a full charge and a dark hydrometer indicates the battery still needs charging.

18. If the battery has a sealed top and no built-in hydrometer, you can hook up a digital voltmeter across the battery terminals to check the charge. A fully charged battery should read 12.5 volts or higher.

19. Further information on the battery and jump-starting can be found in Chapter Engine electrical systems and at the front of this manual.

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