Yet another Alternator question !!!!!

[VicS]

Usually the current flowing through the warning light bulb provides the field current to initially excite the alternator. Once it is generating, the bulb goes out and the alternator is providing its own field current.

A larger wattage bulb might help to get it going a bit sooner.

Are the pulleys the correct size or is the alternator running more slowly than designed?

Brushes and slip rings OK? Probably if it delivers the output you'd expect once it is going. Likewise the field diodes. Edit: Oh its new anyway.

If it performs to spec once it is going it is not something to worry unduly about I suggest.

[johnwest]

On my Ford Lehman engines the alternators are "excited" by an oil pressure switch so until the oil pressure comes up after start up no charging.

j

[Billjratt]

Had the same problem when I changed to car alternators for more output.
The pulley size is the key factor, make it as small as the drive belt can tolerate.
I have to "blip" mine before the charge light goes out and keep the revs up to get full charge. If I drop revs, the current drops but the light stays out.
I'm getting my (alloy) pulley turned down this winter.

[VicS]

make it as small as the drive belt can tolerate

But dont exceed the max RPM for the alternator. Unlikely but possible if you overdo it.

[Billjratt]

Didn't mention that because I take from a high-revving petrol car and use on (very) lethargic diesel with rev limiter.- Which it never hits when in gear, as I get max hull speed at about 1800 revs, and don't do fuel-wasting black smoke.
In this case, I don't see us getting rev-critical anyway as it has to be woken up, and I assumed -for some reason that the OPster was the same type of user as me.
I guess a Mobo using the proper power band may have to be more careful - just in case any are out there looking for more amps...

[VicS]

I'd guess that the OPs engine is a marinised version of one of the Ford 1.6 litre units used in their cars. If that's so and if the engine still has the same rev range then you would expect it to have have the same size pulleys.

I had a Fiesta many years ago with a 1.6 litre diesel engine. No problems with the alternator on that, in fact never touched the engine all the while I had it. Got rid of it when the bodywork started rusting away. Engine would have run for ever I reckon.

[Jcorstorphine]

Thanks to all who replied. I am sure the pulley is OK as it is very small, in fact I do have a problem with belt squeal when the alternator kicks in so looking to try and fit a heavier belt. I will try a larger wattage lamp in parallel with the little indicator lamp I have installed. The engine is an old Fiesta 1600 cc OHC diesel unit which I have rebuilt.

Regards

John

To quote another Formite. "One day I will have a boat which works"