Battery Load Test

A fully charged battery must have cranking capacity. To provide 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 capability of the battery.

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

1. Disconnect and isolate the battery negative remote cable first. Then disconnect and isolate the positive Jump Start cable.

Volt-Ammeter-Load Tester:

Volt-Ammeter-Load Tester Connections:

2. Use a suitable Volt/Ammeter/Load tester connected between remote battery terminals. Check the open circuit voltage of the battery. Voltage should be equal to or greater than 12.4 volts. If below 12.4 volts charge battery, perform the same test at the battery. Remove both battery cables the negative cable first. If the voltage is still below 12.4 perform Battery Charging procedures.

Remove Surface Charge From Battery:

3. Rotate the load control knob of the carbon pile rheostat to apply a 260 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 two minutes, and then verify open circuit voltage.

Load 50% Cold Crank Rating:

5. Rotate the load control knob on the tester to maintain 50% (260) 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 off.

Battery Load Temperature Table:

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 Battery Load Test Temperatures 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.