For 1990-2009 cars

Important: Load testing requires the use of battery side terminal adapters (AC Delco part number ST-1201, GM part number 12303040 or equivalent) to ensure good connections. Do not load test a frozen battery. Replace it instead.

1. Use a voltmeter to check the voltage across the terminals. With all loads off, and the green dot showing in the hydrometer, the voltage should be 12 volts or higher. If not, replace the battery.
2. With voltmeter still attached, connect a battery load tester across the battery terminals.
3. If the battery has been on charge, apply a 300 ampere load test for 15 seconds to remove surface charge from the battery. Remove the load. (Do not complete this step if the battery has not been recently charged.)
4. Wait 15 seconds to let the battery recover. Apply the specified load located on the battery label or Refer to Battery Usage . Read the voltage after 15 seconds, them remove the load.
5. If the voltage does not drop below the minimum, the battery is good and should be returned to service. (The battery temperature must be estimated by feel and by the temperature the battery has been exposed to for the proceeding few hours). Refer to Battery Voltage vs Temperature .
6. If the voltage drops below the minimum listed, replace the battery.