Battery Capacity Test

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. Voltage readings at 15 seconds for good battery (battery capacity test) are shown in the following table:

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.