Wiring Delco 12SI for external reg

[cwyckham]

Does anybody have experience with re-wiring a Delco 12SI to bypass the internal reg and allow me to hook it up to an external regulator?

I'm planning on using an MC 614 and 94 amp 12SI to charge 400 Ah of AGM batteries with a 30 hp Westerbeke W27.

Also not sure about mounting of the 12SI. I may have to modify the original Mitsubishi bracket to bolt up to the 12SI.

Am I going nut here? $700 for a Balmar or $100 for a delco, and I can get a delco replacement or parts just about anywhere in the world. Sounds good to me if I can figure out how to set it up.

[Efraim]

Converting an alternator from internally regulated to external is no big deal - in fact it's pretty straight forward, a google search should bring up quite a few "how to" articles if you want to do it yourself. Most good auto shops will also do if for you.
There are many alternatives to Balmar, however I don't think any of them come in white.

Here's an example of a conversion - not your alternator, but you get the idea.

[cwyckham]

Originally Posted by Efraim

Converting an alternator from internally regulated to external is no big deal - in fact it's pretty straight forward, a google search should bring up quite a few "how to" articles if you want to do it yourself. Most good auto shops will also do if for you.
There are many alternatives to Balmar, however I don't think any of them come in white.

Here's an example of a conversion - not your alternator, but you get the idea.

The nice externally mounted regulator on the Leese-Neville makes it a whole lot easier than the Delco, I think. Nice that there's a kit as well. I haven't seen a kit for the Delco. Your idea of letting the alternator shop do the work isn't a bad one either, though I try to do as much of my own work as possible so I learn more.

The mounting is another issue. The L-N may have a better option. The Mitsubishi 2 1/16 sale seems to be pretty unusual.

[magicmoments]

It's been a while but memory thinks the older Delco 10DN brush assembly will fit the 10 & 12 SI and it was external regulated so much better for your plan.

The Leece Neville is a much better choice overall as it has massive heat sinks for the rectifiers and will take a lot of abuse.

Just my loonie's worth.

[cwyckham]

I just found this document: http://www.perfectswitch.com/downloads/DELCOSI5010.pdf

Sure looks like a bit of a job. Oddly, they remove the diode pack. I assume you wouldn't want to do that with and MC-614 and would just leave it in place. I need a stator output as well for my tach. I think you can get those as an option on a 12SI and not sure how that would fit into the picture.

[guyfromiowa]

The diode pack, or 'diode trio' in the Delco SI is used to provide a half-wave signal voltage of approximately 8 volts to the internal voltage regulator. The full-wave three-phase power rectifier diode set, ( six diodes ), is left intact. The rectifier bridge converts the alternating current to a fairly smooth output with one side of the rectifier bridge connected to the ground side and one side to battery positive. The little diode trio, (small black box with four leads), does not provide output voltage. With the internal voltage regulator removed the diode trio has no function. Also, with external regulation, the output voltage can be anything from six volts to forty-eight volts. Remember that wattage output will be the limiting factor. If you double the output voltage and the output wattage stays the same your new output amperage will be about half. Also, my two volts worth here, the older Delco SI alternators are among the easiest to service. And parts are pretty cheap and available, too.

Guy

[Blue Stocking]

---and with seperate front and rear housings, you can get any arrangement you wish for your bracket mount.

[FlyingCloud1937]

Originally Posted by guyfromiowa

The diode pack, or 'diode trio' in the Delco SI is used to provide a half-wave signal voltage of approximately 8 volts to the internal voltage regulator. The full-wave three-phase power rectifier diode set, ( six diodes ), is left intact. The rectifier bridge converts the alternating current to a fairly smooth output with one side of the rectifier bridge connected to the ground side and one side to battery positive. The little diode trio, (small black box with four leads), does not provide output voltage. With the internal voltage regulator removed the diode trio has no function. Also, with external regulation, the output voltage can be anything from six volts to forty-eight volts. Remember that wattage output will be the limiting factor. If you double the output voltage and the output wattage stays the same your new output amperage will be about half. Also, my two volts worth here, the older Delco SI alternators are among the easiest to service. And parts are pretty cheap and available, too.

Guy

Hi Guy,

Glad to see your post, i have family in Iowa.

I just thought you might appreciate this link, and even the group of DIY'ers at the site. Would love to have ya join the discussion over there.

Lloyd

[cwyckham]

Originally Posted by guyfromiowa

The diode pack, or 'diode trio' in the Delco SI is used to provide a half-wave signal voltage of approximately 8 volts to the internal voltage regulator. The full-wave three-phase power rectifier diode set, ( six diodes ), is left intact. The rectifier bridge converts the alternating current to a fairly smooth output with one side of the rectifier bridge connected to the ground side and one side to battery positive. The little diode trio, (small black box with four leads), does not provide output voltage. With the internal voltage regulator removed the diode trio has no function. Also, with external regulation, the output voltage can be anything from six volts to forty-eight volts. Remember that wattage output will be the limiting factor. If you double the output voltage and the output wattage stays the same your new output amperage will be about half. Also, my two volts worth here, the older Delco SI alternators are among the easiest to service. And parts are pretty cheap and available, too.

Guy

Thank you for the amazing detail, Guy. You cleared that right up. So it looks like the rewire is pretty do-able, though I'll also need to to a stator tap while I'm in there (looks like I'll be able to figure out how to do that.

[cwyckham]

Originally Posted by Blue Stocking

---and with seperate front and rear housings, you can get any arrangement you wish for your bracket mount.

This sounds promising. I've only ever seen them with a single foot near the pulley. I didn't realize there were other configurations available.