Jim Grant's Tech Tips
Van, Charging System Question
Q:#I recently installed a new battery in my ‘82
Chevy Van. It starts fine but the needle in the gauge never moves off
discharge unless the vehicle is idling, then it moves to the halfway point.
All the other gauges are working fine. Do you think it will ruin the new
battery or do you think the gauge is not working?
Relying on the dash gauge as the sole answer to your question may leave
you in a not so nice place or time, looking for a phone. To really answer
your question requires a voltmeter. With the ignition key in the off position,
battery voltage should be 12.6 volts. This reading indicates a fully charged
battery. Anything less means that the battery is low in charge. With the
engine running, all accessories off, the battery voltage should test in
the range of 14 to 14.5 volts, give or take a bit depending on temperature.
This indicates that the charging system is functioning. If the gauge on
the dash shows a discharge then you know that the gauge is less than reliable.
The charging system performance also must be checked (engine running)
with the accessories on at idle and at 1500 RPM. This tests the ability
of the charging system to keep up with the demands of the electrical system.
Keep in mind that the primary job of a battery is to store electricity.
Once the engine is running it is the job of the charging system to recharge
(replace the electrical energy used to start the engine) the battery and
provide for the electrical demands of the vehicle.