Re: Alternator!!!!

No, they wouldn't be affected. The alternator produces AC, so mankes no difference which way it's spinning.

As Guy says, the only possible issue is cooling, but with that kind of load it should be fine.

"Rich" mumbled:

Shouldn't be. The regulator feeds current to the rotor which creates a moving ('cos it's a rotor!) magnetic field which sweeps round the coils built into the casing. The regulator varies this current according to the voltage output. The clever bit is that a DC current through the rotor will produce a magnetic field whichever way it's going, and the field will vary just the same if it's going one way as the other.

The rectifier diodes will take care of everything else.

Lucas

some honda engines run backwards

MrCheerful

Only thing that might be handed is the cooling fan but on most cars these days they all seem to be radial blades anyway. Also on a typical alternator with a keyless pulley the nut on the end of the shaft the nut will tend to slacken giving no drive.

So if it does not matter which direction it rotates why doesn't it work???? Is it critical as to the wattage of the ignition warning lamp?? old one was for a dynamo would this be correct for the alternator? Rich

"AWM" mumbled:

Ah. That'll teach me to only play with old cars...I though they were mostly angled.

Nothing a good bodger can't fix with threadlock or a touch of weld.

"Rich" mumbled:

Yes. It relies on the current passed to sense the voltage on the other side of the lamp.

Possibly not...who's to say!

Not particularly critical, are the brushes making contact, I can imagine them being worn & sticking if it's run the opposite way to the way they've bedded.

If it was dynamo before was it positive earth?

Alternators only work on negative earth systems AFAIK (although I bet there is some old junk somewhere that is positive earth alternator) Is the alternator properly earthed? Have you got the warning light working? as without a light alternators do not like to start charging.

MrCheerful

it was a dynamo before, and yes it was Negative earth!!! ( only there to charge the battery )

Last minitute update, doh!!!!!!!!!!!!

old 3 cylinder Lister air cooled desile ( like you got in those old dumpers ) max revs hmmmm about 1500rpm????? output pully on engine for alternator half rpm of engine, belt drive to alt gears up, so alternator rpm is now the same as the engine rpm!!! Are you all still with me on this!!! so my next question is does anyone know the minimum rpm an alt needs to actually charge???

Yes the lamp is on and makes no attempt to go out even revving the nads out of the engine but I don't know what the engine rpm is at the throttle setting it sound fast but its noisy anyway, but the pulley sizing means that the alt does the same rpm as the engine so at high revs it looks as though it is whizzing round, have got a v8 landy and I am going to calculate the alt rpm in relation to the engine to give me some idea of alt speed at tickover which does just charge!!!!! the other idea I have just thought of is to use an electric drill with a socket to fit the pulley nut and spin it fast and see what happens??

Rich

"Rich" mumbled:

Starting to sound a lot like the alternator's naff.

Yes I think it might be naff I will do more checks to try to get the revs up on the alt and see what happens I will let you all know the out come when I get some results!!!

Thanks Rich

From memory, a Lucas ACR alternator gives max output at around 6000rpm (alternator speed) and is safe to around 15,000; they are normally geared around 1:2 for the engine (Alternator rpm = 2xEngine RPM). Check the pulley circumferences, and see if you can get around that sort of figure. They will produce power from around 1000 alternator rpm (ish)

Phil

Great will try some idea's and we will have to see what happens thanks very much and I will give it a go on sat.

Rich

"> From memory, a Lucas ACR alternator gives max output at around 6000rpm