Open-Circuit Voltage Test

STANDARD PROCEDURE - OPEN-CIRCUIT VOLTAGE TEST
A battery open-circuit voltage (no load) test will show the approximate state-of-charge of a battery. This test can be used in place of the hydrometer test when a hydrometer is not available, or for maintenance-free batteries with non-removable cell caps.

Before proceeding with this test, completely charge the battery. Refer to Standard Procedures for the proper battery charging procedures.
1. Before measuring the open-circuit voltage, the surface charge must be removed from the battery. Turn ON the headlamps for 15 seconds, then allow up to 5 minutes for the battery voltage to stabilize.
2. Disconnect and isolate both battery cables, negative cable first.

Testing Open Circuit Voltage:

3. Using a voltmeter connected to the battery posts (see the instructions provided by the manufacturer of the voltmeter), measure the open-circuit voltage.

Open Circuit Voltage Table:

See the Open-Circuit Voltage Table. This voltage reading will indicate the battery state-of-charge, but will not reveal its cranking capacity. If a battery has an open-circuit voltage reading of 12.4 volts or greater, it may be load tested to reveal its cranking capacity. Refer to Standard Procedures for the proper battery load test procedures.