Battery Charging

Charging Procedures
Before recharging a discharged battery, inspect and service the following conditions if they exist:
1. Loose generator drive belt.
2. Pinched or grounded Generator (GEN)/voltage regulator wiring harness.
3. Loose harness connections at the generator.
4. Loose or corroded connections at battery, starter motor solenoid relay switch, and/or engine ground.
5. Excessive battery drain due to hood, glove compartment, and courtesy lamps remaining energized (damaged or misadjusted switch, glove compartment left open, etc.).

Charging Notes
Cold batteries do not readily accept a charge. Allow batteries to warm up to approximately 5°C (41°F) before charging. The warming-up period may require four to eight hours at room temperature, depending on the initial temperature and the battery size.

A battery that has been completely discharged may initially be slow to accept a charge, and in some cases may not accept a charge at the normal charger setting. To charge batteries in such a condition, use the dead battery switch on chargers equipped with such a switch.

Batteries which have been discharged for a prolonged period of time (over one month) and have an open circuit voltage of less than two volts may show no indication of accepting a charge even when the dead battery switch is used. The initial charge rate of batteries in this condition is so slow that the ammeter on some chargers will not show any indication of charge for up to 10 minutes.

A method of determining whether a battery is accepting a charge is as follows:
- Follow the charger manufacturer's instructions for the use of the dead battery switch. If the dead battery switch is a spring-loaded type, hold it in the ON position for up to three minutes.
- After releasing the dead battery switch and while the battery charger is still on, measure the battery voltage. If it shows 12 volts or higher, the battery is accepting the charge and is capable of being recharged. Cold batteries below 5°C (41°F) may require up to two hours of charging before the charging rate is high enough to show on the charger ammeter. All non-damaged batteries can be charged by this procedure. If a battery is damaged, it must be replaced.

A rapid recharge procedure has been developed for recharging batteries that have passed the Load Test and only need a recharge. This can be due to: in-service no-start battery failures (vehicle will not crank due to low battery state of charge) or battery discharged in vehicle due to key OFF loads.

The battery can be rapidly recharged by using either of the following methods:
- Perform a 2-hour charge using 20 A constant current (manual setting on charger).
- Perform a 2-hour charge using a constant potential (automatic setting on charge).