The Ford Barn

john charlton · 10-07-2017, 01:17 PM

A fellow club member went to 12 volts and donated his 6v alternator to me . He had just bought the car and had not used it prior to converting so the alternator was unknown but as it was for free (I paid shipping). I fitted it to see how it performed . The alternator charges at approx 3 amps whether or not the headlamps are on or off . It balances the load no problem but never charges more than 3 amps . Other cars I have with an alternator peg to 20 amps on starting and then rapidly drop to maybe 1 amp . I know nothing about alternators and wondered if there is some kind of internal adjustment to vary charge rate . The alternator has been converted and by the small pulley and is marked on the case 12v negative ground . Any advice from learned Gentlemen of the Barn ???

John in rainy dark roll on Xmas in sunny Chandler AZ Suffolk County England .

Tom Endy · 10-07-2017, 01:35 PM

I have a 6-volt positive ground alternator on my Victoria, it has been there for many years. When I start the car up the ammeter pegs full 20 amps positive because the alternator is trying to replenished the power the starter pulled out of the battery. Very quickly it returns to zero as the battery regains a full charge. It will stay at zero when the lights or other loads are turned on because the alternator picks up the load.

Tom Endy

john charlton · 10-07-2017, 03:13 PM

Yes Tom this is exactly as my other alternators behave . I was wondering what I could do to get this one to do the same . At the moment the battery cranks the motor over no problem but I seldom do short trips so I suppose 3 amps surfices . Maybe I ought to leave the headlights on for a while with the motor off to see if the alternator senses that battery is a bit down .

John in same place same weather .

steve s · 10-07-2017, 06:50 PM

I tried three times to suggest you run the battery down a bit with the headlights, but each time my text was mysteriously deleted before I could send. If it doesn't charge at more than 3 amps then, something's wrong.

Steve

Also, turn on high beams AND stand on brake pedal AND turn on any other electrical accessories AND blow horn, all at the same time with motor running to see if your alternator can handle maximum load.

A nice thing about alternators is that you can have any auto electric shop check them out. I don't believe that there are any adjustments you can make yourself. There are multiple possibilities for which voltage regulator your alternator might have built into it--best to get professional help. There will be plenty of opportunities for do-it-yourselfing.

Mike V. Florida · 10-07-2017, 11:38 PM

Measure the battery without the car running and then measure it at a high idle. There should be a difference. a fully charged 6 volt battery that has sat for a day or two should read close to 6.3 volts. An alternator running should read 7.7 volts due to the regulators used in the one wire conversions. See if you get these readings.

Bruce Adams · 10-08-2017, 01:23 PM

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I think you would be wise to take it to an alternator shop for a check of the diodes that work as a voltage regulators.
My alternator goes up to 10 amps at the start and the meter then hangs at zero while running, even with headlights on, hi or lo beam.

katy · 10-09-2017, 09:49 AM

Quote:

I think you would be wise to take it to an alternator shop for a check of the diodes that work as a voltage regulators.

The diodes are not regulators, they're rectifiers, they change the AC from the field windings into DC which then has to be controlled by a (voltage) regulator.

BTW, taking it to an alternator shop is still a good idea.

10-07-2017, 01:17 PM	#1
john charlton Senior Member Join Date: May 2010 Posts: 1,304	6 volt pos ground alternator question . A fellow club member went to 12 volts and donated his 6v alternator to me . He had just bought the car and had not used it prior to converting so the alternator was unknown but as it was for free (I paid shipping). I fitted it to see how it performed . The alternator charges at approx 3 amps whether or not the headlamps are on or off . It balances the load no problem but never charges more than 3 amps . Other cars I have with an alternator peg to 20 amps on starting and then rapidly drop to maybe 1 amp . I know nothing about alternators and wondered if there is some kind of internal adjustment to vary charge rate . The alternator has been converted and by the small pulley and is marked on the case 12v negative ground . Any advice from learned Gentlemen of the Barn ??? John in rainy dark roll on Xmas in sunny Chandler AZ Suffolk County England .

10-07-2017, 01:35 PM	#2
Tom Endy Senior Member Join Date: May 2010 Location: Southern California Posts: 3,131	Re: 6 volt pos ground alternator question . I have a 6-volt positive ground alternator on my Victoria, it has been there for many years. When I start the car up the ammeter pegs full 20 amps positive because the alternator is trying to replenished the power the starter pulled out of the battery. Very quickly it returns to zero as the battery regains a full charge. It will stay at zero when the lights or other loads are turned on because the alternator picks up the load. Tom Endy

10-07-2017, 03:13 PM	#3
john charlton Senior Member Join Date: May 2010 Posts: 1,304	Re: 6 volt pos ground alternator question . Yes Tom this is exactly as my other alternators behave . I was wondering what I could do to get this one to do the same . At the moment the battery cranks the motor over no problem but I seldom do short trips so I suppose 3 amps surfices . Maybe I ought to leave the headlights on for a while with the motor off to see if the alternator senses that battery is a bit down . John in same place same weather .

10-07-2017, 06:50 PM	#4
steve s Senior Member Join Date: May 2010 Location: Kalamazoo Posts: 1,656	Re: 6 volt pos ground alternator question . I tried three times to suggest you run the battery down a bit with the headlights, but each time my text was mysteriously deleted before I could send. If it doesn't charge at more than 3 amps then, something's wrong. Steve Also, turn on high beams AND stand on brake pedal AND turn on any other electrical accessories AND blow horn, all at the same time with motor running to see if your alternator can handle maximum load. A nice thing about alternators is that you can have any auto electric shop check them out. I don't believe that there are any adjustments you can make yourself. There are multiple possibilities for which voltage regulator your alternator might have built into it--best to get professional help. There will be plenty of opportunities for do-it-yourselfing. Last edited by steve s; 10-07-2017 at 06:58 PM.

10-07-2017, 11:38 PM	#5
Mike V. Florida Senior Member Join Date: May 2010 Location: South Florida Posts: 14,054	Re: 6 volt pos ground alternator question . Measure the battery without the car running and then measure it at a high idle. There should be a difference. a fully charged 6 volt battery that has sat for a day or two should read close to 6.3 volts. An alternator running should read 7.7 volts due to the regulators used in the one wire conversions. See if you get these readings. __________________ What's right about America is that although we have a mess of problems, we have great capacity - intellect and resources - to do some thing about them. - Henry Ford II

10-08-2017, 01:23 PM	#6
Bruce Adams Senior Member Join Date: May 2010 Location: Northport, NY Posts: 1,597	Re: 6 volt pos ground alternator question . Sponsored Links (Register now to hide all advertisements) I think you would be wise to take it to an alternator shop for a check of the diodes that work as a voltage regulators. My alternator goes up to 10 amps at the start and the meter then hangs at zero while running, even with headlights on, hi or lo beam.