The following general information has been assembled as a guide for battery inspection and testing. Refer to the appropriate Original Equipment Manufacturer’s service manual for specific information pertaining to battery inspection and testing procedures and safety precautions for your vehicle. Before performing any electrical system diagnosis or repair, make sure the battery has been:
- Visually inspected.
- Fully charged.
- Performance tested.
Before a performance test can be conducted, it is necessary to inspect the battery for visual defects and adjustments.
- Make sure the battery is the proper size and type for the vehicle application. Compare each of the following characteristics to the vehicle manufacturer’s specifications:
- Cold Cranking Amps (CCA) rating Note: The cranking amps (CA) rating is different than the CCA rating.
- Physical size and mounting style.
- Post orientation
- Make sure the battery does not have loose posts, and the case is not cracked, bulging, or showing signs of leaking fluid.
- Make sure the battery surface is free of dirt and moisture.
- Make sure the battery connections are clean and corrosion free. This includes the frame and body ground connections and connections at the starter motor, starter solenoid and alternator.
- Make sure the battery cables are properly sized.
- Make sure the battery cables have no frayed wires and the insulation is intact.
- Make sure the battery cables are flexible and bend freely. Popping or crackling sounds while bending the cables indicate corrosion. Replace the cables.
- Check the electrolyte solution if the battery has access. Add enough distilled water to maintain the electrolyte level just below the filler tube.
- Check that the battery is properly secured and the mounting hardware is not too tight.
Performance testing and charging
Before performance testing can take place on the battery, a visual check must be done to determine if the battery’s physical condition is adequate for proper operation.
- If the electrolyte solution has been adjusted during the visual inspection, charge the battery for 15 minutes at 15 to 25 amps.
- Charge the battery to obtain at least 12.6 volts (full charge). After charging the battery apply a 150 amp load for 10 to 15 seconds to remove any surface charge. Check the open circuit voltage. If 12.6 volts or above is not measured, replace the battery and continue to evaluate the charging system.
- If the open circuit voltage is 12.6 volts or above, load-test the battery. A good battery will be capable of producing one-half of its CCA rating for 15 seconds and maintain a voltage reading of 9.6 volts (adjusted at 70º F) or above (Table 1). Perform the load test twice, waiting approximately 30 seconds between tests.
- Check for parasitic loads at the battery. An excessive parasitic load can drain the battery in a short period of time. Draws in excess of 0.35 amps should be investigated. Refer to the Original Equipment Manufacturer’s service manual for the parasitic load specification for your vehicle.