Hey yall, quick question... got a brand new one wire on my Model A. Wired in correctly... there's only one way to do that, so, yeah... Battery shows 12.2 volts, start engine, rev the piss out of it to get the alternator to charge, still showing 12.2... 12.1... 12.0... you get the picture. Disconnected the alternator from the car's electrical system (to isolate from the battery). Measured with a voltmeter between a ground point on the alternator case & the output post. Shows 3 volts at idle & 6.5 volts when I rev it. Supplier wants me to ship it back to him in St Louis... I'd rather not... what are the odds it's just the voltage regulator?
A lot of one wires are just converted regular alternators. I've always preferred to run internally regulated alts over one wires. And you can get those at any part store cheap
I understand your first test results which tell that the alternator is not charging. However, I do not know what you are trying to accomplish with the second test. Since the alternator gets it's field current from the battery, you must be seeing the result of some residual magnetism. Not knowing what alternator you have, is it possible to full field the alternator. On the old 10SI Delco there was a half moon shaped hole that you could put a small screw drive in and ground out the regulator. This would full field the alternator and tell you if it was capable of charging. If it charged with the regulator grounded it meant the regulator was bad. If it didn't charge, there was some other problem internally in the alternator.
I should probably have prefaced this post by saying I don't know jack about alternators... I am pretty good at the physical, mechanical stuff but when it comes to electrical diagnostics I might as well be talking to women for all the sense it makes to me. http://www.wagnerproducts.com/model-a-alternator.htm The alternator kit I ordered is this one, the 100 amp 12 volt model. Maybe you can tell looking at it what the alternator itself is, nothing with the kit says exactly other than being Delco. What I have looks the same as the 10SI unit you described from the outside. I figured if the pulley was spinning and I checked it with a voltmeter while disconnected from the battery, it would tell me if the alternator was generating any current. All I know is, spinny thing spins, electricity comes out. I'm pretty confident I can take the unit apart to replace the regulator but I don't really know how to know for sure if that's the issue. Tried that - no dice. At the same time, I also bypassed the terminal box on the car with a jumper straight from the BAT post to the battery, just to be sure there wasn't a problem in there somewhere - nothing.
We are gonna use this truck around the shop, for parts runs, local service calls, etc. with our business name on it, so I intend to run an air compressor off it and who knows what else (lights for parades, speakers??, who knows, whatever). Figured I might as well get the higher output.
Yes sir. That was my first thought. The unit has a label on the outside identifying it as a 12v model.
You mentioned a voltage regulator. Most one wire alternators are self regulating, so if you've got a voltage regulator it should be removed and wired without an external regulator. Like this:
Hopefully he meant the voltage regulator that's inside the alternator. The other possible parts that could be bad include the field and stator windings, the diodes, the brushes, and....what else is there in there? Another small diode set?
If that's the regulator your alternator has, you should be able to see that small tab through a half moon shaped hole. That is the little tab that you ground to full field the alternator.
Unlike generators, alternators need some voltage to energize the field. Generator have large pole shoes that retain magnetism, alternators do not. You have to send a small current through the rotor to energize the field and make it charge. Just spinning the alternator without a voltage connection will not make it work.
Ran in to an issue with a newly rebuilt SI alternator. Some shops use a small pin/toothpick through the back of the case to hold the brushes back for reassembly. They forgot to take it out. Brushes weren't making contact. Check that out.
Nearly every person I've ever met getting a high output alternator actually had no need for one. Why pay $100+ extra for 30 extra amps on a semi sketchy looking part when an over the counter 70 amp would more than cover needs?
22 years with a 100a one wire built by a local auto electric shop , cost was only minimally higher ( about $75 total in 2000) than a stock version , has operated flawlessly for over 50k miles now . What's not to like ?
I get ya, but not many auto electric shops around anymore. 20 years ago, I could take a starter, etc in to get rebuilt. Place isn’t there anymore. I guess one could do a google, ship to and from, or buy with free shipping like most online places do.
You probably won't save any money but you could order the parts & DIY , that way you know what you have .
heres goes.... why not just send it back?????it doesn't work.... they'll send you one that does...PITA,,,,but, thats how mail order works.... had you of bought it local,you could just walk in and put in on the counter and they would test it... but at the same time you can take it to auto zone and they will test it... or any other automotive shop... from your posts, i'm leaning towards it a 6v alt.....
Sorry , screwed that up , but the point is , they're both 100 a & both under $100 . The extra capability sure won't cause any problems. .
Sending stuff back is a pain...but in this case, it might be the answer. I like to build my cars around parts that I can get easily, where possible. So I don't have to depend on a special alternator actually working. As for how many amps you need...well, that depends on what modern electrical stuff you have in the car. If you're running an air ride suspension, you need some electrical power to run the compressor. If you can get away with only using lights and a simple ignition system, then you can get away with a 37A alternator, although they're pretty hard to find unless you get an original and rebuild it yourself. Which is something you can do, if you're patient.
Never , ever, test an alternator with the output wire unhooked and engine running. You'll destroy the diode trio and possibly the rectifier bridge. Generator, sure...no sweat.
2 reasons... 1- the truck isn't done but it's done enough that it's in active use. I can drive it with a dead alternator, I can't drive it with no alternator. Don't really want to wait another 2, maybe 3 weeks for it to snail mail to missouri, then for the guy to get around to checking it out and repairing it, then snail mailing back. Not only am I just impatient but also I don't want the truck disabled for 3 weeks occupying space at our very tight quarters shop. 2- this is an opportunity for me to learn stuff and become a better mechanic. Nobody around here will dig any deeper into an alternator than to check if it has output & replace if not... I'm happy to learn stuff and develop my skills... but this is an area I have little exposure to so I don't have my bearings with it. I have the unit apart now and know how to put it back together... yesterday I'd never opened an alternator case, tomorrow I'll have it back in service when the new regulator comes in, if it was the regulator... if not I'll take it to the auto electric guy rather than ship it. If what I learn is "don't fuck with that" then so be it, but I'd rather take a crack at it than not.
Might help your learning if you take a lot of pictures of the alternator parts as you work on it, so maybe someone with some experience could look over your shoulder and see something wrong that you didn't know to notice.
you don't have to take the truck to bench test an alt.... just the alt...and you did learn don't fuck with it already... now you can't send it back.... but....now you will learn how to fix it..... or buy another one...
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