Alternator Question

Ken/SC

Ken/SC

Member
I am running a 6V alternator on my "A". It is one on those exciter kind that does not cut on until you get up to speed. What should the amps show when cruising down the road? I put on of those small diameter pulleys on it. That did not seem to change much. It is usually at around 3 amps when cruising. I have not had problems with dead batterys though.
The lights are dim at night when stopped until you get back up to speed.

KM
 
Ken, if your lights dim at idle, either the alternator isn't functioning at that engine speed or the battery is on the weak side - or both. I suppose that one other cause could be poor ground(s) for the lights, requiring a LOT of current to light them well. I would run a load test on the battery to see how strong it is and start there.
 
After you've been driving long enough to recharge the battery from its startup load, the alternator should just barely show a postive charging rate--3 amps is probably ok going down the road. It should be about the same with your lights on, going down the road.

After the car hasn't been driven for a while, I've had mine take over an hour on the highway to recharge the battery and return to one or two amps rate.

Alternators are supposed to maintain voltage at idle, but there are limits! Too slow an idle and it will brown out.

Steve
 
Even with the smallest 2" alternator pulley you will not have the same alternator idle performance as a modern car. The "A" has a crank pulley 4.5" in diameter and idles at 500 rpm, modern cars have crank pulleys 6"+ and idle 600+ rpm. Unless you are a big city downtown taxi driver who seldom sees 10mph, the amount of idling with dimmed lights amounts to nothing. I suppose if you have AC running, lots of accessories, and drive nights with high wattage halogens, it may be a concern. Cars that had generators (not alt's) with a red idiot light routinely saw red while idling. Pretend you're a dumb blonde- see nothing, don't worry, enjoy. All is good.
 
There is a kit you can add to your altenator even if it self exciting which plugs into the 1 & 2 spots at the rear of the altenator. One wire goes from the hot side of altenator to one terminal and the other goes thru a diode to one side of the coil. Works good on a 12V negative ground system. Same set up should work on 6V negative ground sustem. Could possibly work on a 6V posative ground by reversing the ground. If intrested send me an email jrelliott42@gmail.com and will send you a schematic. WIth this setup you start charging immediately and no high reving of engine to kick start the altenator.
 
jrelliott said:
There is a kit you can add to your altenator even if it self exciting which plugs into the 1 & 2 spots at the rear of the altenator. One wire goes from the hot side of altenator to one terminal and the other goes thru a diode to one side of the coil. Works good on a 12V negative ground system. Same set up should work on 6V negative ground sustem. Could possibly work on a 6V posative ground by reversing the ground. If intrested send me an email jrelliott42@gmail.com and will send you a schematic. WIth this setup you start charging immediately and no high reving of engine to kick start the altenator.
Click to expand...

...or yet another easier way (for me at least) is to use the brake light switch to energize the alternator. It has been years since I have even used a GM alternator (since the Model A generator has become so bulletproof) but as I recall, there is no need to even use a diode with the brake light switch.

.
 
You can use any thing to energizer it, brake lite . head light , horn, are you can put a push button under the dash rail. it will start charging after that. After it energizer you don't want it to stay on. Bill
 
Unless you are going to sit idling for a long time, I don't think it is a problem. I have a 6v alternator and quartz halogen headlights. When I start my car, the alternator is not charging, but as soon as I start up in first gear, it starts. Usually my car is charged up after driving about 5 minutes.......the battery would have to real run down for it to charge as long as some have said. Also, at a stop light if I have the idle set real slow, it does not charge, but a few minutes of that doesn't seem to hurt much. If I don't want it to discharge a little bit, I just use the hand throttle to set the idle up a bit.
Terry
 
You must log in or register to reply here.
Back
Top