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

Tools Required:

J 39200 Digital Multimeter

1. Use the J 39200 in order to measure the voltage at the battery terminals. If voltage is below 11 volts, the charge current will be very low and the battery may take longer to accept current in excess of a few milliamps.
2. Set the battery charger on the high setting.
3. Connect the charger leads to the battery terminals correctly because some chargers feature polarity protection circuitry that prevents charging. A completely discharged battery may not have enough voltage to activate this circuitry, even though the leads are connected properly. It will appear that the battery will not accept charging current. Follow the charger manufacturer's instructions in order to bypass or override the circuitry. This action will turn on the charger and charge a low-voltage battery.
4. Battery chargers vary in the amount of voltage and current the chargers provide. The following times are required for the battery in order to accept measurable charger current at various voltages:

•	16.0  volts or more up to 4 hours

•	14.0-15.9 volts up to 8 hours

•	13.9 volts or less up to 16 hours

Important: If the charge current is not measurable at the end of the above charging times, replace the battery. If the charge current is measurable during the charging time, the battery is good. Complete the charging in the normal manner.

5. Recharge a completely discharged battery for a sufficient number of ampere hours (AH) in order to restore the battery to a useable state. Use the reserve capacity rating of the battery in order to determine the amount of time necessary in order to completely recharge the battery. For capacity ratings, refer to Battery Specifications in Battery Usage . Divide the reserve capacity rating by the amount of ampere charge in order to determine how many hours of charging are needed. (Rating divided by amps = hours).

For example: A battery with a reserve capacity rating of 75, charged at a rate of 10 amperes, will take 7.5 hours to fully recharge (75 divided by 10 = 7.5). The same battery, charged at a rate of 25 amperes, will take 3 hours to fully recharge (75 divided by 25 = 3).

6. Batteries recharged by this procedure should be load tested in order to determine serviceability. Refer to Charging System Check .