Alternator

[Matt V6]

Hi

Can someone please explain to me how the alternator works ?

I have a 2.5 v6 and have read about the alternators having a regulator, is this true ?

Does the regulator alter the output to the battery/charging voltage depending on the battery state ?

Thanks in advance
Matt

[okenora]

Regulator is slight misnomer if you use the common English understanding of it, the word limiter describes its purpose better. The alternator produces in excess of the 14v or so needed so the regulator limits this back down to the 14v needed. It also helps to remove ripple on the voltage which is an artefact of the rectification of the AC voltage the alternator produces

[Astraeus]

Originally Posted by Matt V6

Hi

Can someone please explain to me how the alternator works ?

I have a 2.5 v6 and have read about the alternators having a regulator, is this true ?

Does the regulator alter the output to the battery/charging voltage depending on the battery state ?

Thanks in advance
Matt

Simple check to see if alternator is producing sufficient current. Get a test meter and measure voltage at battery when car switched off. Should read 12 point something volts. Start car and repeat measurement. Should now read 14 point something volts. If still reading 12 alternator not working.

Chris

[HarryM1BYT]

Originally Posted by Matt V6

Hi

Can someone please explain to me how the alternator works ?

I have a 2.5 v6 and have read about the alternators having a regulator, is this true ?

Does the regulator alter the output to the battery/charging voltage depending on the battery state ?

Thanks in advance
Matt

The alternator is able to produce around 120v AC, via its three phases. The three phases are rectified to produce the DC voltage needed by the car. A single phase would produce a very ragged DC, so the more phases the smoother.

The stator winding, the none rotating part, actually produces the voltage and the current, but the amount is controlled by the amount of magnetic effect produced by the field coils and it is the field which is varied to control the output. Because the field coils are rotating, the current has to be fed into them via brushes and slip rings.

The output of the alternator first has to be converted to DC by three rectifiers, one for each phase. That then feeds into what is known a a regulator. The regulator simply compares the output voltage against its reference voltage, if the voltage is too high, it reduces the field coil current, if its too low it increases the field coil current. It also measure the current it is outputting and ensures it remains below its maximum current limit.

The actual output voltage when running should be between 14.5 and 14.0v, depending upon electrical load and whether the car has just been started, or has been running for a while.

Likely, you didn't really want to know all of that, but you did ask :-)

Basically if you measure more than 14.0v across the battery, with the engine running, your alternator is fine. If it shows more than 14.0v with engine running, everything turned on and at around 2,000rpm it would seem to confirm all is fine.

[COLVERT]

And here's a pretty picture for you---------

[COLVERT]

http://auto.howstuffworks.com/alternator2.htm





Have a look in here.

[COLVERT]

Originally Posted by Matt V6

Hi

Can someone please explain to me how the alternator works ?

I have a 2.5 v6 and have read about the alternators having a regulator, is this true ?

Does the regulator alter the output to the battery/charging voltage depending on the battery state ?

Thanks in advance
Matt

Now you have read all of this go to the section----'really really useful info' at the top of the main page and find out what your alternator is doing to your battery.








Colvert.

[COLVERT]

Originally Posted by okenora

Regulator is slight misnomer if you use the common English understanding of it, the word limiter describes its purpose better. The alternator produces in excess of the 14v or so needed so the regulator limits this back down to the 14v needed. It also helps to remove ripple on the voltage which is an artefact of the rectification of the AC voltage the alternator produces

Sorry----beg to differ.

Regulator describes its action perfectly.

[Matt V6]

Hi all

Thanks for all the replies and information.

I have run the car today with the diagnostic on test 9 for the voltage, And it didn't move far from 14.2v all day.

When I got home I put my meter across the battery, and it showed 11v ?

I was once again confused and got a second meter, which gave a reading of 14.1v.

From this I can be happy that my alternator is fine, and my multimeter is the faulty part !

Once again thanks.

Matt