Battery Charging

A battery is considered fully charged when it will meet all the following requirements.
- It has an open circuit voltage charge of at least 12.4 volts (refer to Battery Open Circuit Voltage table).
- It passes the 15 second load test, refer to Battery Load Test Temperatures Table.

WARNING: DO NOT ASSIST BOOST OR CHARGE A FROZEN BATTERY.EXPLOSIVE GASES FORM OVER THE BATTERY, DO NOT SMOKE, USE FLAME, OR CREATE SPARKS NEAR BATTERY.

CAUTION: Disconnect the battery NEGATIVE cable first, before charging battery to avoid damage to electrical systems. Do not exceed 16.0 volts while charging battery. Refer to the instructions supplied with charging equipment.

Battery electrolyte will bubble inside of battery case while being charged properly. If the electrolyte boils violently, or is discharged from the vent holes while charging, immediately reduce charging rate or turn off charger. Evaluate battery condition. Battery damage may occur if charging is excessive.

Some battery chargers are equipped with polarity sensing devices to protect the charger or battery from being damaged if improperly connected. If the battery state of charge is too low for the polarity sensor to detect, the sensor must be bypassed for charger to operate. Refer to operating instructions provided with battery charger being used.

CAUTION: Do not overcharge Battery. Refer to Battery Charging Rate table.

After the battery has been charged to 12.4 volts or greater, perform a load test to determine cranking capacity. If the battery will endure a load test, return the battery to use. If battery will not endure a load test, it must be replaced. Properly clean and inspect battery hold downs, tray, terminals, cables, posts, and top before completing service.

Battery Charging Time Required

WARNING: NEVER EXCEED 20 AMPS WHEN CHARGING A COLD -1 °C (30 °F) BATTERY. PERSONAL INJURY MAY RESULT.

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

Size Of Battery

Battery Charging Timetable:

A completely discharged large heavy-duty battery may require more recharging time than a completely discharged small capacity battery, refer to Battery Charging Timetable for charging times.

Temperature
A longer time will be needed to charge a battery at -18 °C (0 °F) than at 27 °C (80 °F). When a fast charger is connected to a cold battery, current accepted by battery will be very low at first. In time, the battery will accept a higher rate as battery temperature warms.

Charger Capacity
A charger which can supply only five amperes Will require a much longer period of charging than a charger that can supply 20 amperes or more.

State Of Charge
A completely discharged battery requires more charging time than a partially charged battery. Electrolyte is nearly pure water in a completely discharged battery. At first, the charging current amperage will be low. As water is converted back to sulfuric acid inside the battery, the current amp rate will rise. Also, the specific gravity of the electrolyte will rise. Refer to Battery Charging procedures.