The Stovebolt Site Forums The Shop Area The Electrical Bay 12V Conversion--Which Alternator to Use?

What alternators do you guys use? I have a 1952 6400 that I am going to change over. I have used small amperage Delco alternators on old tractors before but had trouble with them running when they were supposed to shut down. The first one worked fine but the next two wired identical gave trouble. Anyhow, I don't want the same problem with this. Any suggestions?

I use the internally regulated, 3-wire alternator...I think they are designated as 10 SI. They're cheap, plentiful, and I think even the small ones put out about 60 amps.

i bought a single wire alt. at a place that rebuilds starters/alt.for $45.00. used an all thread bolt/nuts/washers etc on the bottom using the existing generator bracket with the holes notched a little. turned the existing adjustment arm upside down, flattened it out and it worked out fine for me. (54 chevy with 62 chevy 235 motor)

You just can't beat the Delco 10si or 12si alternators! I have a 12si ... and HERE is the best way to wire them up.

Hi,
I know this an old topic, but did want to open a new one on the same topic. I see a lot on this conversion with a internal regulator alternator, but nothing if your using the external regulator. So how is this wired?

Art

I ordered mine from jegs because the single wire from Auto Zone would not charge it because the truck had a low rpm.

Thanks, but what i was asking is that i'm using an alternator with out the internal regulator, so how is wired. How is the 12v external regulator and alternator wired.

Art

Save yourself a lot of grief and just use a 10-SI- - - - -the external regulated alternator (Delcotron) was a piece of junk, and the regulators were worse. It's been close to 50 years since they were original equipment on anything, and finding a regulator would be a royal P I T A. Wiring it to work right is also a challenge. If you absolutely must use that setup for some unfathomable reason, find a Motor Magazine repair manual that covers cars from the mid 1960's to the mid-70's and follow the wiring diagrams in the "charging system" section.
Jerry

OK. 54 chevy 3100, pretty original truck, 86K, 3sp column shift, 235 eng. I did this conversion a few years back from a 12v with the generator to the alternator. The converted generator to 12v did not seem to work very well. But still seem to run down my battery every few months. Did the install using the DA plug and all that. Pretty sure I'm not charging, with engine running it shows 12.15volts, not running 12.25volts, so that says I'm not charging? Is it a bad alternator or internal regulator.

Please disregard the previous post about the wiring for external regulator.

Thanks,
Art

Nope, it's not charging. Normal running voltage against a fully charged battery needs to be 14.5 or slightly higher. It sounds like your alternator has at least one leaky diode that allows a parasitic drain of the battery- - - -a small constant current that drains the battery over the span of a few days, or maybe weeks. If you run the engine regularly, does the battery stay charged? You can check for parasitic drain a couple of ways- - - -disconnect the big output lead at the alternator and leave it loose for a week. Check to see if the battery stays up. If so, change the alternator. Another method is to disconnect the same lead and use the "ammeter" section of a digital multimeter to check for current leakage. More than a few milliamps of parasitic drain is too much.

You could also have some other item causing a drain. The constant voltage "keep alive" circuit on a sound system like a CD player, etc. will drain a battery over a span of several weeks if the engine isn't run occasionally.
Jerry

Thanks. Got a new alternator. They went to test mine and it would not test on the tester. It kept failing with out running through a test cycle. Put a new one on the tester and that tested good which it should. So must of been bad. Tried to get diodes for at the part store and everyone question why do you want the diodes. Waiting now for some paint to dry on a bracket that needed repainting.



Art

If you want to use an external regulator (and I did only because I had originally converted one of my 50s era vehicles in the early 80s and wanted to leave it as I had done it all those years ago. The set up gave me no troubles at all for over 30 years so I felt no need to make any real changes), you can easily do so but there are a couple of things to think about. There are two kinds of regulators for those units, mechanical and electronic. The mechanical regulators are fine to use, and they are available on ebay all the time, as long as your running an essentially stock alternator and not pulling a lot of amps. Read that if you have added halogen headlights, electric fuel pump, after market gauges, air conditioning, stereo and amps, the system will not keep up depending on the aggregate load. Now, there are some alternatives. For example, Tuff Stuff alternators sells an externally regulated 100 amp alternator that is essentially 10si guts in the earlier style alternator case. Wires up exactly as before using all the earlier wire hook up. Here is the rub. The mechanical regulator uses a point system that opens and closes to regulate the charging. If you are pulling a lot of amps with accessories, the points open and close non stop and then fails. If you have a eternally regulated system and a bunch of electronic accessories, and you can see your headlights flicker a bunch, you are in the zone. So instead of using the mechanical regulator (which you would think would be the best regulator but is not if you have some high amp draws) you use a heavy duty electronic regulator (also sold by Tuff Stuff).

Two years ago I added an electric fuel pump, stereo, and halogen headlights and relays to that vehicle. The charging system could not keep up. Went with 100 amp tuff stuff externally regulated alternator (100 amp was actually a little over kill but the cost difference was not that much) and their heavy duty electronic regulator. The only thing I had to do was re-clock the alternator to get the access to the plugs and other wiring correct. Other then that it was plug and play, works perfectly for the past two years. Its an option if you want to keep the externally regulated set up. otherwise, if you are converting from scratch, the 10si and 12 si are probably the better approach.

Looking for a place to buy the kit Alan Horvath listed. No reply from his web page. Printed the instructions. Thanks for any help!

If a piece of 8 gauge wire and a few terminal connectors qualifies as a "kit", try your local parts store. Installing a 10-SI is so simple my granddaughter could probably do it!
Jerry

Jerry.
Thanks, he showed a couple of blocks and a diode to make it display with the original dash light. His procedure sounded pretty involved, but maybe not necessary.
Thanks
John Paul

If you want an idiot light, just put one inline between the ignition switch and the white wire of the 2-wire plug that connects to one of the two terminals on the perimeter of the 10-SI alternator. The red wire gets jumpered to the big output terminal at the back of the housing. If you don't want to buy the factory plug, just use #12 wire and flat female terminals. Looking at the back of the alternator, the constant 12V wire attaches to the right terminal, and the idiot light ground attaches to the left one. That wire is optional- - - - -if you're using an ammeter instead of an idiot light, just leave that terminal open. The diode is needed if you choose to attach an "exciter" wire from the ignition switch to the left terminal to prevent a backfeed to the ignition system that keeps the engine running when the ignition is turned off.
Jerry