Should read 14 volts.
You need to check the charging system with a volt meter. It should have 13.9 to 14.2 volts at the battery with engine running.
14 volts
With a volt meter or multi-meter. With the engine off the battery should read 12 volts at the battery posts. With the engine running it should read from 13.5-16 volts. Red positive probe goes to positive red post on battery, black negative probe goes to negative battery post or any metal ground on the engine.
You should read 12.6 volts with a digital volt meter on a fully charged battery with the engine not running.
When our 93 grand prix battery light came on it meant that we needed a new battery. We tested the battery with a volt meter and the battery read 1 volt, it should be 12volts. Still wondering how to reset the battery light?
Need to check the battery with a volt meter, it should read 12.5 volts. If that is good, then check the cables on the battery and make sure they are clean and tight, then check the conections on the starter and the ground cables going to engine block and frame. check body grounds also. Good luck.
1,4 meter
Use a vom meter, or battery tester and with the engine running voltage should be approximately 14.5 volts.
The head lamps should not get dim. Dim light are an indication of low voltage. You should have a volt meter in the instrument panel. If the voltages is not reading about 14V when the engine is running, you have a bad battery or alternator. It should read over 12V with the engine not running and the ignition in the on position. It should not drop below about 9-10 when cranking the engine. If you have low voltage during cranking and normal voltage at other times, you probably need to replace the battery.
If your test meter is an analog type of meter there should be a zeroing screw on the meter face that is connected to the needle movement. Turn this screw to zero the meter. If the meter is a digital there should be a potentiometer, probably in the battery compartment that can be used to zero the display.
The battery light on a car is just an idiot light and does not necessarily mean the battery is bad. More likely is a bad alternator. If you or a friend has a digital volt ohm meter set it to VDC (Volts DC) and put the meter on the battery terminals with the car running. If your alternator and voltage regulator (They are combined in newer cars) then the meter should read about 13.8 to 14.5 VDC. If it reads less have your alternator tested and/or replaced.
Automotive Battery VoltagesAssuming your voltage meter is accurate, the battery is fully charged, when the key is turned on, without the engine running, and no accessories turned on, the meter indicated voltage should be 12 volts. When the engine is running and the alternator is charging the battery, the voltage should indicate anywhere between 13 volts to about 14.6 volts.Answer 2 - A wider Acceptable Range13.5 −16 volts is acceptable with the engine running.