Will stock wiring take a 6 volt alterator?

A

aaron griffey

Member
My customer wants to install a 35 amp, 6 volt alternator to his '31 A.
Will the stock wiring hold up to the output of that alternator?
Or should I install larger wire from the alt. to the amp meter and to the starter?
 
I do not have a textbook answer but...

My first Model A had a six volt alternator and original wiring and I never had any problem with it.
 
It will work fine. Just install a fuse on the starter if it doesn't already have one. The alternator doesn't need a fuse, but if it's original wires it's best to have one incase of a short. I think 6 volt alternators only come in 30 amp or 60 amp for high output.
 
Unless you've got some non-standard high-draw accessories headlights, you will be ok. Just because the alternator is capable of cranking out 35 amps, doesn't mean that it will be doing that most of the time. But, it will if you've got halogens, tail lights, cowl lights, brake lights, turn signals and your horn all going at once. Even then, you only need to worry about the particular wires to the high-load items, whether or not you have an alternator. Actually, the switches and contacts might be your weak links. You can find tables of wire gauges for different current loads by googling those words.

Steve
 
I don't know why the customer would give up the more reliable generator in favor of an alternator, but the reason for adding a fuse when you go with the one wire alternator is so you can pull the fuse during storage to avoid killing the battery.

For anyone installing a fuse be sure the terminals are soldered. I've heard lots of reports of bad connections and trouble due to loose fuse terminals.

I don't use a fuse myself and also enjoy no charging or headlight worries using what Henry put on the car, plus my EVR for proper battery charging and less drag on the fan belt and engine.
 
Thanks to all who replied.
This guy is getting the 35 amp alternator from Vintage Ford in Sacramento.
We will take out his 8 volt battery, install the large (original size) battery cables, install a new 6 volt battery and check connections on the amp meter and starter, etc.
The car has good wiring and no extra-draw items. It has directional lights and stock headlights.
If it were mine I would just install a Fun Projects voltage regulator and 6 volt battery and cables.
I disagree with Tom about the life of a generater being longer than an alternator.
I have never in my 55 years of being a mechanic seen a gen. run much over 100,000 miles but I have seen MANY alternators with over 150,000. I have two right now!
But I would take his advice about the fuse except this guy is driving this car at least 5 nights a week anyway.
My model T will sit more than 7 months (Veteran's Day untill July 4th) and start without ever recharging the battery and it has an alternator, BUT I have a ground disconnect switch. It never occured to me that that has been saving my battery for the last 13 years but I know Tom is right.
Thanks again to all.
 
aaron griffey said:
..
I disagree with Tom about the life of a generater being longer than an alternator. I have never in my 55 years of being a mechanic seen a gen. run much over 100,000 miles but I have seen MANY alternators with over 150,000. I have two right now!
...
I have a ground disconnect switch. It never occured to me that that has been saving my battery for the last 13 years but I know Tom is right.
Click to expand...

I suppose there must be a support group for folks who had to have their Model A's generator rebuilt after 100,000 miles?

Do you guys really mean that disconnecting the battery makes it hold its charge or somehow last longer EVEN IF no short develops or no load was left turned on (like someone did in my garage over the winter--aargh!)?

Steve
 
I'll have to meaure it sometime, but I understand the one wire alternators have a small feed to help them energize. That's why most guys with the one wire alternator always remove the fuse for storage.

As far as the life of a generator, I rebuilt my powerhouse about 10 years ago and don't expect to have the cover off in my lifetime. Those bearings are large and the cavity to hold grease is large. My commutator is very smooth and I don't think the brushes will wear out in my lifetime, but if they do, it's a 5 minute job to change them.

Alternators have 9 diodes that can and do burn out. I've replaced a lot of them. I've also replaced a lot of alternator brushes and bearings. Also with the alternator an extra load is placed on the belt and water pump bearing, so that's two more things to wear out sooner.
 
Last edited:
Hey, this guy has been talked into an alternator.
You know the story,"Somebody once told me.....".
If he has the time and the money and wants the engine in up-side-down, I'll do it.
 
I think the argument of alt/gen is a moot one. The generator will last a lifetime because of the few miles we put on the car. An alternator will do the same. The alt will start it's charge curve at a much lower rpm but again, so what.

If you want an improved charging system, install a regulator, install a battery disconnect of good quality to the ground side of the system, inspect the battery every 6 months for water level and terminal brightness and be sure the wiring is fused.
 
The Alt is not wired to have a drain to make it charge. It uses residual magnetism in the rotor . That is why you have to speed the eng up to charge. You can put a push button switch wired to the field terminal. The switch could be put under the dash rail where you can not see it. You don't wont current going to it all the time. Just push it one time after you start the car and you don't have to speed it up. It can be wired outher ways with a light , but the push button is the easy thing to do.
 
I just want to say, I'm not arguing about which is best . An Alt or Gen will both work well. I would want some type of reg on the gen. Like the ones Tom sells. Of course that would not be completely stock , You just can't see it. LOL. My Model A is " fixed " up very nice but it is not a show car. The owner before me had my shop put the alt on it. It's to much trouble for me to change it back. If it ant broke I don't fix it. With the hood closed you don't see it.
 
cars56 said:
Any advise on wiring in an external diode leading from the alt to prevent battery drain?
Thanks
Click to expand...

The fact that you have an alt means that you already have diodes in the unit. It is the diode that turns the alternating output to a constant output.
 
We just removed a 6V alternator that just had about 60 miles of service. Rear bearing was shot. Wiring is of a large enough gauge to handle the alternator. We have gone back to the generator for a while or at least until we repair the alternator.
 
You must log in or register to reply here.
Back
Top