•	Use a charger, with an end voltage of 16 V, equipped with a voltmeter that is accurate to within 1 percent.

The time required to charge a battery will vary depending upon the following factors:

1. The size of the battery -- A completely discharged, heavy-duty battery requires more than twice the recharging time as a completely discharged, light duty battery.
2. The temperature -- The colder the battery, the more time it takes to recharge. When a fast charger is connected to a cold battery, the current accepted by the battery is very low at first. Then, as the battery warms, the battery accepts a higher rate of current.
3. The charging capacity -- The higher the charger amperage, the less time it will take to charge the battery.
4. The state-of-charge -- A completely discharged battery requires more than twice as much charge time as a half charged battery. Because the electrolyte is nearly pure water and a poor conductor in a completely discharged battery, the battery accepts very low current at first. Later, as the charging current causes the electrolyte acid content to increase, the charging current also increases.

Tools Required

GM P/N 12303040

Notice: Turn OFF the ignition when connecting or disconnecting the battery cables, the battery charger or the jumper cables. Failure to do so may damage the PCM or other electronic components.

1. Do not charge a battery with a green hydrometer dot unless it has just been discharged, such as in cranking.
2. When charging side-terminal batteries while on-vehicle, use the following procedure:

2.1.	Turn OFF the charger.

2.2.	Connect the charger positive lead to the positive cable terminal located in the engine compartment on the right side.

2.3.	Connect the negative charger lead to a solid engine ground, such as the generator mounting bracket.




3. When charging side-terminal batteries out of vehicle, install battery side terminal adapters.

Tighten
Tighten the battery side terminal adapters to 15 N·m (11 lb ft).

4. Make sure all battery terminals are clean and tight.
5. Best results occur when charging a battery that is at room temperature. A battery that is extremely cold may not accept current for several hours.
6. Charge the battery until the hydrometer has a green dot.
7. Inspect the battery every half hour after starting the battery charger.
8. Tap the hydrometer lightly to dislodge any air bubbles. The bubbles may cause a false indication.
9. After charging, load test the battery. Refer to Battery Load Test .

Tools Required

J 39200 Digital Mulitmeter

The following procedure should be used to recharge a very low or completely discharged battery. Unless the procedure is properly followed, a perfectly good battery may be needlessly replaced.

The required battery charge time varies according to the voltage capabilities of the battery charger. A charger of less than 14 volts could take up to 16 hours before the battery appears to be accepting current.

1. Measure the battery voltage at the battery terminals using the J 39200 Digital Multimeter.

•	A reading of less than 11 V indicates that the initial charging will be very low.

•	It could take some time before the battery accepts current in excess of a few milliamperes.

2. Set the battery charger on the highest setting.
3. If necessary, disable the polarity protection circuitry:

•	This circuitry, available on most chargers, prevents charging unless the charger leads are properly connected to the battery terminals.

•	A completely discharged battery may not have enough voltage to activate this circuitry, even though the leads are properly connected, implying that the battery will not accept a charge.

•	Most chargers have an override or a bypass function so that the charger will turn ON and charge a low voltage battery.

4. To determine the amount of hours the battery may need to be charged, the following calculation can be made:

•	The reserve capacity rating on the battery label is the number of ampere-hours of charge required in order to produce the green hydrometer dot.

•	After the meter on the charger starts to show current flow, note the number of amps being accepted.

•	Determine the reserve capacity of the battery. Refer to Battery Usage .

•	Divide the reserve capacity by the number of amps shown on the meter to determine how many hours of charging is needed.

5. When the green dot appears in the hydrometer, discontinue charging.
6. If the green hydrometer dot is not visible after an ampere-hour charge equal to twice the reserve capacity rating, replace the battery. Refer to Battery Replacement .
7. After charging, load test the battery. Refer to Battery Load Test .