Alternator question

john charlton

john charlton

Well-known member
Got my AZ 29 fordor 60B import on the road. It has an alternator 6v pos ground. The car has the aftermarket fuse holder on the starter setup. It has been blowing 20 amp fuses which I think I have traced to the repro brake light switch . Looks like the ground was a misaligned terminal post grounding on the case but not 100% sure,time will tell. I hope to do a steam rally tommorrow but a bit concerned I might blow a fuse (or several)on the 40 mile round trip. I thought I would take a jumper wire just to feed the pos terminal on the coil as to get me home .I would disconnect the red wire from the coil as well so I dont back feed the short although the ignition will be switched off . Question is will the alternator get damaged if not connected to the battery as the generator would or do I need to by pass the fuse holder and connect the alternator to the battery ???. This is the first alternator I have had in an A so not familiar with them.

John in cool dark evening England.
 
I have no idea how great the risk, but I have read that an alternator also should not be run unless connected to a battery.

Steve
 
I'd be more concerned about driving the car 40 miles without a brake light than with the alternator disconnected.:eek: Nobody pays attention to hand signals, especially the downward hand for 'stop'.

If the alternator has an internal regulator, disconnecting all wires to it (1, 2, or 3 wire) will render it safe to run with no load or battery. Do NOT ground the output, like you would with a model A generator that has no load attached. That still won't fix your electrical problem, and you could end up stranded anyway unless you disconnect the wires on the brake switch. There are several repop brake switches that are prone to fail and short. Same with repro light sockets.
 
Hi John, we have a club member who drove 200 miles back home, day light hours, with the fuse mounted by the starter not installed. This meant that his alternator output was open circuited.
His igniton is wired directly to the battery.
His only problem was the next day the battery wouldn't turn over the motor.
He charged the battery, installed the fuse and all is OK. This happened back in July.
His car is 12 volts negative ground alternator with electronic igniton.

Based on this case, you should be OK. Your results may vary.

Regards,
herb
 
Thank you all for the info.I had taken the repro brake light switch completely apart and made sure the terminal posts were centralised .Actually it does look fairly well made (Japan) I think most likely the inner nut was loose enough on one terminal which allowed it move sideways and ground on the case I dont think that will a problem now,just hoping it was not a red herring and the shorting problem actually lay elsewhere.I know not to ground the alternator output as I am sure it would cremate it without doubt ,exact opposite to the generator, thanks for the advice on that anyway.

John in dark England.
 
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