Corrosion of the battery terminals and cable clamps interferes with both the flow of power out of the battery and the charge flowing into the battery from the charging system. This can result in a ""no start" condition. If the battery becomes completely discharged, battery life may be shortened. In some cases, a totally discharged battery may not readily accept a charge.
To reduce the need for service and to extend battery life, keep the top of the battery, the battery terminals, and the cable clamps clean and free of corrosion. Make sure the cable clamps are tightly fastened to the battery terminals. If corrosion is found, disconnect the cables and clean the clamps and terminals with a wire brush. Neutralize the corrosion with a solution of baking soda and water. After installing the cables, apply a light coating of petroleum jelly to the cable clamps and terminals to help prevent corrosion.
FLUID LEVEL (EXCEPT MAINTENANCE FREE BATTERIES)
Check the battery electrolyte level at least once a month, or more often in hot weather or during periods of extended car operation. The level can be checked through the case on translucent polypropylene batteries; the cell caps must be removed on other models. The electrolyte level in each cell should be kept filled to the split ring inside, or the line marked on the outside of the case.
If the level is low, add only distilled water, or colorless, odorless drinking water, through the opening until the level is correct. Each cell is completely separate from the others, so each must be checked and filled individually. If water is added in freezing weather, the car should be driven several miles to allow the water to mix with the electrolyte. Otherwise, the battery could freeze. If the battery needs water often, check the charging system.
- Loosen the negative battery cable nut using an adjustable or box wrench and battery pliers. The jaws on battery pliers are specially designed for gripping the cable clamp bolts.
Using a battery cable clamp puller, remove the negative battery cable from the battery post.
WARNINGDo not twist or pry the cable clamp off of the post using a screwdriver. This may crack the top of the battery or cause damage to the internal battery components and leakage at the terminals.
- Repeat Steps 1 and 2 to remove the positive battery cable.
- Clean both battery posts and the cable clamps using battery cleaning tools. There are tools available for both top post and side post batteries.
Remove the remaining corrosion deposits from the battery and cables by flushing with a baking soda-water solution comprising 2 teaspoons of baking soda and 1 cup of water.
WARNINGDo not allow the solution to enter the battery as this could weaken the electrolyte. Be careful not to allow the flushed deposits to come in contact with painted surfaces as paint damage may result.
- Follow the negative battery cable to the engine block and check the connection. If it is loose or corroded, remove the cable and clean the cable end and block with sandpaper, then reconnect the cable.
- Follow the positive cable to the starter and clean and tighten, if necessary.
- Apply a small amount of petroleum jelly around the base of each battery post, to help reduce the possibility of corrosion. Do not coat the battery post.
- Install the positive battery cable on the positive battery post. It may be necessary to spread the clamp slightly using a clamp spreader tool. Do not twist the clamp in an attempt to seat it on the post. When the clamp is seated, tighten the clamp nut.
- Repeat Step 9 to install the negative battery cable.
- After the cables are installed, coat the top of each terminal lightly with petroleum jelly.
Specific Gravity (Except Maintenance Free Batteries)
At least once a year, check the specific gravity of the battery using a hydrometer. The hydrometer has a squeeze bulb at one end and nozzle at the other. Battery electrolyte is sucked into the hydrometer until the float is lifted from its seat. The specific gravity is then read by noting the position of the float. If the difference between cells is 50 points (0.050) or more, the battery is bad and must be replaced.
If the difference between cells is less than 50 points (0.050) and one or more cells are less than 1.225, charge the battery for 20 minutes at 35 amps and perform the capacity test. If the battery fails, it must be replaced. If it passes, add water, if necessary, and charge the battery. If the difference between cells is less than 50 points (0.050) and all cells are above 1.225, perform the capacity test. If the battery fails, replace it.
It is not possible to check the specific gravity in this manner on sealed (maintenance free) batteries. 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.
A high rate discharge battery-starter tester and a voltmeter are used for this test.
- Turn the control knob on the tester to the OFF position and set the voltmeter selector switch to the 10 or 20 volt position.
- Connect both positive test leads to the positive battery post and both negative test leads to the negative battery post. The voltmeter clips must contact the battery posts and not the high rate discharge tester clips, or actual battery terminal voltage will not be indicated.
- Turn the load control knob on the tester until the ammeter reads approximately 3 times the ampere hour rating of the battery. For example, a 48 ampere hour battery should be tested at 150 amperes load.
- With the ammeter reading the required load for 15 seconds, record the voltmeter reading. Do not leave the high discharge load on the battery for longer than 15 seconds.
- If the voltmeter reading is 9.6 volts at 70°F (21°C) or more, the battery has good output capacity and will accept a charge, if necessary.
- If the voltmeter reading is below 9.6 volts at 70°F (21°C) and the battery is fully charged, the battery is bad and must be replaced. If you are not sure about the battery's state of charge, charge the battery.
- After the battery has been charged, repeat the capacity test. If the voltage is still less than 9.6 volts at 70°F (21°C), replace the battery. If the voltage is 9.6 or more at 70°F (21°C), the battery is good.
A cold battery will not readily accept a charge, so allow the battery to warm up to approximately 40°F (5°C) before charging, if necessary. This may take 4 to 8 hours at room temperature, depending on initial temperature and battery size.
A completely discharged battery may be slow to accept a charge initially and in some cases may not accept a charge at the normal charger setting. If the battery is in this condition, charging can be initiated using the dead battery switch, on battery chargers so equipped. Follow the charger manufacturers instructions on the use of the dead battery switch.
If the battery will accept a charge, it can be charged using the automatic or manual method. If the charger is equipped with an automatic setting, the charge rate is maintained within safe limits by automatic adjustment of the voltage and current in order to prevent excessive gassing and discharge of electrolyte. It will take approximately 2 to 4 hours to charge a completely discharged battery to a usable state. A full state of charge can be obtained by charging at a low current rate of 3 to 5 amps for a few more hours.
If the charger does not have an automatic setting, the battery will have to be charged manually. Initially set the charging rate for 30 to 40 amps and charge for approximately 30 minutes or as long as there is no excessive gassing or electrolyte discharge. If there is excessive gas emission, slow the charge rate to a level where the gassing stops. Excessive gas emission will result in non-replaceable loss of electrolyte.
- Disconnect the negative and then the positive battery cables from the battery.
- Remove the battery hold-down clamps.
- Remove the battery using a battery carrier. If a battery carrier is not available, grip the battery at opposite corners with your hands and carefully lift the battery from the tray.
- Check the battery tray for corrosion or other damage. Clean the tray with a wire brush and a scraper.
- Clean the battery and the cables.
- Install the battery and retain with the hold-down clamps.
- Connect the positive and then the negative battery cables.