The Ford Barn

rotorwrench · 06-24-2025, 06:55 PM

Normally the Delco 10si alternator is a 3-wire 12-volt unit but years ago someone developed the 6-volt conversion. They changed the internal voltage/current control unit and added a jumper to swap polarity. These are strictly a one wire unit. One thing I've noticed about them is that output voltage is higher than what a 6-volt battery should receive. None of the ones I've checked put out 7.2-volts. It's more like 7.8 or more. Running with lights on all the time will help the battery.

There is a new voltage regulator out again that will control a stock model A generator. These set ups will at least charge the battery within normal parameters. The guy who sells them is into model T starters and has a web site.

2speed · 06-24-2025, 09:24 PM

Checked the battery and it tested good. Couldn't get an accurate reading on the battery voltage because two digital voltmeters jumped around, a lot. Didn't bring out the Simpson 260 yet. I order a new regulator and I'm going to try that when it comes in....

Badpuppy · 06-26-2025, 07:10 AM

Quote:

Originally Posted by rotorwrench

There is a new voltage regulator out again that will control a stock model A generator. These set ups will at least charge the battery within normal parameters. The guy who sells them is into model T starters and has a web site.

https://modeltstarters.com/product/6...o-ford-script/

Jeff Stevenson. Still having trouble with the positive ground version for model A. Hopefully coming soon.

Badpuppy · 06-27-2025, 07:34 AM

Had another thought. One of the six diodes may be blown, which would be consistent with your symptoms. 3 in the diode trio and three button diodes pressed into the finned rectifier. Might check while you have it apart. Make sure replacements are for positive ground.

Your new regulator may have current protection, but don't bet on it.

06-24-2025, 06:55 PM	#1
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 17,410	Re: Alternators Normally the Delco 10si alternator is a 3-wire 12-volt unit but years ago someone developed the 6-volt conversion. They changed the internal voltage/current control unit and added a jumper to swap polarity. These are strictly a one wire unit. One thing I've noticed about them is that output voltage is higher than what a 6-volt battery should receive. None of the ones I've checked put out 7.2-volts. It's more like 7.8 or more. Running with lights on all the time will help the battery. There is a new voltage regulator out again that will control a stock model A generator. These set ups will at least charge the battery within normal parameters. The guy who sells them is into model T starters and has a web site.

06-24-2025, 09:24 PM	#2
2speed Senior Member Join Date: Apr 2022 Posts: 105	Re: Alternators Checked the battery and it tested good. Couldn't get an accurate reading on the battery voltage because two digital voltmeters jumped around, a lot. Didn't bring out the Simpson 260 yet. I order a new regulator and I'm going to try that when it comes in....

06-27-2025, 07:34 AM	#4
Badpuppy Senior Member Join Date: Dec 2017 Location: Guthrie, OK Posts: 1,247	Re: Alternators Had another thought. One of the six diodes may be blown, which would be consistent with your symptoms. 3 in the diode trio and three button diodes pressed into the finned rectifier. Might check while you have it apart. Make sure replacements are for positive ground. Your new regulator may have current protection, but don't bet on it.