J 39200 Digital Multimeter

Use the following procedure in order to recharge a very low or completely discharged battery. Carefully follow the procedure in order to avoid the replacement of a usable battery.

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

•	A reading of less than 11 volts 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 high 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.

Important: If the charging current is not measurable at the end of the charging time, replace the battery. If the charging current is measurable during the charging time, the battery is good.

4. The required battery charge time varies according to the voltage capabilities of the battery charger. Charging time at various voltages may be as follows:

•	16.0 volts or more -- up to 4 hours

•	14.0-15.9 volts -- 8 hours

•	13.9 volts or less -- 16 hours

5. In order 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 in order to determine how many hours of charging is needed.

6. When the green dot appears in the hydrometer, discontinue charging.
7. 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 .
8. After charging, load test the battery. Refer to Battery Not Operating Properly .