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 passed the capacity test, charge the battery. Battery Charging
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.
3. Voltage readings at 15 seconds for good battery (battery capacity test).

BATTERY CAPACITY

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

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.