Quote:
Originally Posted by Cam
In regards to the "trick" I use to dignose alternators:
"For good reason there is no evidence that a faultybattery connection while the engine is running creates problems.
As designed, the regulator utilizes a separate sensing wire. This wire terminates at the distribution panel and therefore remains connected, even if the battery lead is disconnected.
As a result the regulator output continues to be monitored and output is controlled, regardless of how when or why the actual
battery connection is broken.
The object is to directly monitor the line voltage rather than battery voltage and in this way voltage
drop is accounted for."
I have posted this without permission of the contact that provided the information, so unless he would like to chime in, it will remain an anonymous source. However, it is reason enough for me to continue doing my process for diagnosing alternator problems.
Although, I do usually use a multimeter to better understand the issue. If the voltage regulator is failing and the alternator is putting off too much current, then disconnecting the battery will not change anything. But if the alternator is providing too little current, it will cause the car to stall out.
|
Cam you and our "anonymous source" are right in the way the reg is connected to the system. It is also right that your way of testing for a faulty alternator was the normal way, in years gone by, but with the amount of electronic components that are now prolific in autos, we can no longer continue to do this.
The problem is not that the battery, is dsconnected from the system, it is the instant of disconnecting the battery, that the high voltage danger occurs.
If the alternator is changing the battery, say 20 amps at 13 Volts (20A x 13V is 250 watts) when it is disconnected and the current stops flowing, the voltage will rise to 260 Volts till the alternators energy is dissipated. It will be only Mille seconds, but it can damage any electronic units that are hit by this voltage.
You may get away with doing 'the test' if the alternator charge is very low, but the average Joe may not realize this, and do damage to their cars electrical system by doing this test.
Harvey.