Battery Capacity Testing

NOTE: Whenever possible, test and charge battery at or near room temperature.

Read the battery open circuit terminal voltage with a digital voltmeter, such as Rotunda 73 Digital Multimeter 105-R0051 or equivalent, capable of reading 0.01 volt. If open circuit voltage is below 12.4 volts and the battery passes the capacity test, charge the battery.

Capacity Testing
1. Use a high rate discharge tester with a variable rate control or a fused rate tester with meter compensation for different battery electrical sizes. Follow instructions supplied with tester for the battery capacity test.
2. Discharge rates at 27°C (80°F) should equal one-half of the cold cranking amps. Review the table showing battery Capacities.
3. For Voltage readings at 15 seconds for good battery (battery capacity test), Review the table showing battery capacities.

BATTERY CAPACITY

Approximate Battery Temperature Minimum Load voltage
27°C (80°F) and above 9.6
21°C (70°F) 9.6
16°C (60°F) 9.5
10°C (50°F) 9.4
4°C (40°F) 9.3
-1°C (30°F) 9.1
-7°C (20°F) 8.9
-12°C (10°F) 8.7
-18°C (0°F) 8.5

4. Wait two minutes and check the open circuit voltage. Measure open circuit voltage with a digital voltmeter capable of reading 0.01 volt.
5. Charge battery for 20 minutes at 35 amps.
6. Repeat steps 1 through 5.