- Measure the battery voltage at the battery terminals using a 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. |
- Set the battery charger on the highest setting.
- 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: 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 it appears to be accepting current, followed up by
several hours of the appearance of charging.
- 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. |
- When the green dot appears in the hydrometer, discontinue charging.
- 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.
- After charging, load test the battery. Refer to
Battery Load Test
.
