Hi all.

Had a problem first time out in the Locost last week at Oulton Park.

The alternator is not charging the battery, the car would start in the morning, but then starting got more sluggish. Eventually we had to jump and push start it. In the afternoon the car packed up completely, seemingly insufficient electrical drive for the fuel pump.

The engine is a Ford 1.3 X Flow, the alternator (I imagine, but can see no name on it) probably Lucas.

There are 2 thick wires coming off it, both of these go to positive on the solenoid.

There is a smaller wire coming off the alternator, which goes nowhere, so I am guessing this is the problem.

The car was previously only used as a 750MC race car, so can`t be sure the wiring was properly installed for all day use.

So where should this wire go?

Cheers

its probably the 'panel light' which has to be connected for alternators to work

Yes- the exciter coils on the alternator require a bit of juice to get the alternator cranking out current. If that wire isn't connected to anything the alternator stops producing power. Always strange to think that you have to put electricity into something designed to create it but hey. Such is life.

Of course if the wire isn't connected the alternator stops using up so many HP.

I did consider fitting a throttle pedal mounted push-to-break switch to that connection IE the alternator produces power on a trailing throttle or mid throttle setting but when you give it the beans the alternator is disconnected.

Not really worth it though. Even at max output (40A) [which it won't be once the battery is charged] the alternator is only using 480 watts which even accounting for poor efficiency is about 1 BHP!!!! So not worth it and would be a tad embarrassing running out of battery if a circuit had lots of straights!

Warning Light "WL" --- goes from Ignition Switch through bulb to small terminal on a three wire alternator.

It is need to energise the rotor windings to provide the initial magnetic field.See halfway down the page on this link

Cheers guys.

So I should wire it to live when ignition is on, with a bulb in the circuit?

[Edited on 18/10/15 by Fandango]

Ive got a very similar problem which i may as well tack on here!

My pinto alternator wasnt charging due to the energiser wire being duff, so i wired in a new feed from a random live wire. Now, the engine doesnt turn off on the key and needs stalling.

Is this just due to a missing bulb? Or does it need a diode in there as well to stop it backfeeding?

Cheers!

quote:

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Originally posted by JoelP
Ive got a very similar problem which i may as well tack on here!

My pinto alternator wasnt charging due to the energiser wire being duff, so i wired in a new feed from a random live wire. Now, the engine doesnt turn off on the key and needs stalling.

Is this just due to a missing bulb? Or does it need a diode in there as well to stop it backfeeding?

Cheers!

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I had that, yes it was down to back feeding and keeping the ignition circuit on. Just. Touching the brake lights stopped the car (when the ignition switch was off)

Fitting a diode in series with the field wire solved it. Can't remember which diode, but pennies.

quote:

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Originally posted by cliftyhanger
I had that, yes it was down to back feeding and keeping the ignition circuit on. Just. Touching the brake lights stopped the car (when the ignition switch was off)

Fitting a diode in series with the field wire solved it. Can't remember which diode, but pennies.

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