Battery Load Test

A fully charged battery must have reserve cranking capacity. This will enable the starter motor and ignition system enough power to start the engine over a broad range of ambient temperatures. A battery load test will verify the actual cranking performance based on the cold crank rating of the battery.

WARNING: IF BATTERY SHOWS SIGNS OF FREEZING, LEAKING, LOOSE SIDE TERMINALS OR EXCESSIVELY LOW ELECTROLYTE LEVEL, DO NOT TEST. ACID BURNS OR AN EXPLOSIVE CONDITION MAY RESULT.

1. Remove both battery cables, negative first. Battery top, terminals and cables should be clean. If green dot is not visible in indicator, charge the battery. Refer to Battery Charging Procedures.

Volt-Ammeter-Load Tester:

Volt-Ammeter-Load Tester Connections:

2. Use a suitable Volt/Amp Meter Load tester connected to the battery side terminals. Check the open circuit voltage of the battery. Voltage should be equal to or greater than 12.4 volts with the green dot visible in test indicator.

Remove Surface Charge From Battery:

3. Rotate the load control knob Carbon pile rheostat to apply a 300 amp load. Apply this load for 15 seconds to remove the surface charge from the battery, and return the control knob to off.
4. Allow the battery to stabilize for 15 seconds, and then verify open circuit voltage.

Load 50% Cold Crank Rating:

5. Rotate the load control knob on the tester to maintain 50 percent of the battery cold crank rating for a minimum 15 seconds.
6. After 15 seconds, record the loaded voltage reading and return the load control to the off position.

Load Test Temperature:

7. Voltage drop will vary according to battery temperature at the time of the load test. Battery temperature can be estimated by the temperature of exposure over the preceding several hours. If the battery has been charged, boosted, or loaded a few minutes prior to the test, the battery would be slightly warmer. Refer to Load Test Temperature table for proper loaded voltage reading.
8. If battery passes load test, it is in good condition and further tests are not necessary. If it fails load test, it should be replaced.