by Crimson Tears » Wed Apr 13, 2005 10:20 pm
Those auxilliary devices will cause your lights to dim because they cause a voltage drop in the system. A good indication your alternator has a problem is the charge light on the dash which may come on with any other combination of lights on the dash while the engine is running.
If you want to check the alternator is charging, you can use the following procedure:
With the engine stopped, connect a voltmeter between the negative and positive terminals of the battery. The reading should be approx 12.6volts.
Start the engine, and the voltage reading on the voltmeter should increase as the engine speed is increased. If this does not occur, the alternator is not charging.
Increase the engine speed gradually. At a moderate engine speed, (around 1500rpm) the voltmeter should flicker slightly, then remain stationary at around 14 volts. This is the regulated voltage.
Switch on the headlamps of the vehicle and observe the effect on the voltemeter. The voltage reading should drop slightly, but still remain stable.
Cheers,
Mike.