What does the voltage regulator do?

[singhters]

BMW 320I 1992 J REG M50


What does the voltage regulator do in the alternator.

I hav a bad idle situation the car really chugs badly, I hav ruled out any sensors on the car and hav no errors as diags have been done, however when I press the demister button the idle smooths out its like its giving too much voltage or something.

I measured the voltage of the battery while the car was idling it read 20Volts which im sure is too much, should it not be lower than that cos am sure its overcharging, i hav read it should be between 13.8 - 14 volts.

Your opinions please.

Appreciated.

 

[Kirby]

Is your volt meter set to DC voltage? If you have it set to AC voltage, you could get a high, wrong reading.

If you are reading 20 VDC, the voltage regulator is bad. The purpose of the voltage regulator is to keep the charging voltage around 13.8 - 14 volts as you have read.

 

[singhters]

Well hope so im not expert with these voltmeters but i hav a skytronic 600 I have the black cable plugged into where it says com and the red one to where it says V.

its the same one as in the link below, I had the diameter thing set to V in the red top left to read upto 20v

http://www.skytronic.co.za/product/product.php?s=600.005

 

[jrt67ss350]

Yep, that's the right setting you should be using on the voltmeter. Looks like your voltage regulator is bad.

 

[singhters]

Strange even when the car was off it was still reading 20v and it was rising its like the battery is over charged.

Im gonna do a test tomorrow by unhooking the alternator and then run the car from the battery direct and see what happens, that way I can rule out which is causing what.

 

[jrt67ss350]

The battery probably is overcharged if the car has been driven like this. Be very careful around the battery because overcharged car batteries can explode.

 

[Kirby]

20V with the car off?? That's odd.... it is possible to overcharge a battery, but not THAT much. That's over 3 volts per cell. You are violating the laws of chemistry and physics by getting over 3 volts out of a lead acid cell!!!!!

Disconnect the + battery cable and take a voltage reading on the battery.

 

[singhters]

Nope its not the batt or the regulator.

It seems to be a short somewhere, So my new question what do i need to do, to deal with a short.

 

[epj3]

20V with the car off?? That's odd.... it is possible to overcharge a battery, but not THAT much. That's over 3 volts per cell. You are violating the laws of chemistry and physics by getting over 3 volts out of a lead acid cell!!!!!

Disconnect the + battery cable and take a voltage reading on the battery.

maybe he is trying to build a time machine.