Yes, Delco integrally-regulated alternators can be modified to use external regulators.
No, it should be producing current with a shaft speed of 1000 +/- RPM.
Most integrally-regulated Delco models must have battery voltage present at the output terminal to work. If a multi-battery isolator has been installed, additional circuitry (a resistor, diode, and relay) is needed. This is applicable mainly to the Leece-Neville units with integral adjustable regulators.
The modification for your unit is a little tricky, hard to lay out without photos, which I don't have. Try these folks for a solution first: DB Electrical, 800-753-2242. They are a big alternator shop in Tennessee.
Most alternator rebuilders and their workers understand as much about how the thing works as a hamburger cook knows about raising a cow. They just put the parts together.
When determining whether your system is working properly, you can't go by a voltage measurement alone. If the voltage is lower than expected, you'll need to know the current, right at the alternator output, to make a clear determination. Alternators are usually rated for output at a shaft speed of 5000 RPM.
Yours is a fairly common challenge in setting up a smaller sailboat for cruising. It is generally best solved by bracketing and fitting a complete installation from the start
Sep 08, 2007
More on Delco Problem by: Matt
I have no experience at all with the Delco. My only experienc was with a now obsolete alternator body, i.e. hard to get so
I sympathise with you since I know it can be a big hassle to try and upgrade an alternator.
I took my alternator to a auto elec to get a new one, after this turned out to be impossible I sent the old one of to get rewound and set up for external regulation. In the end it never got rewound and since it seems practically
impossible to get a more powerful alternator with an identical body, I am faced with modifiying the attachment points on
the engine, i.e. welding on new brackets. All a bit much at present. Sounds a bit similar to your probs.
Few things that might be helpful.
1. If you give all the measurements to an auto electrician (or take the alternator to them)they have books and books on different types of alternators that could fit the specs.
2. I have two pulleys of different sizes on the front of my engine. One is for the water pump and one for the engine driven compressor.
But you might be able to do the same for an alternator that runs at a different RPM. I investigated pully spacers for a new alternator
but in the end have not gone down that road.
3. Some external regs are very sensitive about how you set them up. I know my Ample Power Next Step had all sorts of warnings about which wires to connect first etc. It also has a bunch of LED codes to debug it, a bit primitive but it works
I know there is quite a bit of stuff in the book about this type of thing, but perhaps not on your specific alterantor.
Sorry I couldn't be of more help.
Sep 08, 2007
Pulley Sizea by: Anonymous
I'm aware of the relationship between pulley sizes and rpms. My crank pulley is about 5.5" and the alternator pulley is 2.625" giving me a ratio of about 2.1. That's why in my post I noted the alternator rpms of 2,900 with engine rpms of 1,400 before the alternator starts charging. The smallest pulley one should use is 2.5" so I won't gain anything much there. A larger crank pulley would help but would also drive my water pump faster; probably not desirable. It all comes back to an alternator that just not seem to perform properly. I'm wondering if the rotor is a dud or if the rotor is not compatible with the 100 amp stator they installed (I think the stock stator was 60 amp).
I have of course considered using it as a spare. In fact, before the dodos rebuilt it (w/o my consent!), that was exactly my plan. But I would still like to hear from someone who has converted a Delco 10si or 12si to an external regulator, and how it worked out; if it worked at all
Sep 08, 2007
Change the Pulley sizes by: Anonymous
I have been going through similar issues.
You have to measure the pulley sizes (radius, circumference) to figure out the RPM the alternator will be driven at for different engine RPMS.
So looks like one choice is to change one or both of the pulleys to get the alternator rpm range right.
Alternatively get another alterantor and use the incorrectly set alternator as a spare. Live and learn.
To install a more powerful alternator I broke the problem down into smaller steps. i.e. step 1 get the external reg working with the existing alternator. step 2. either modify alternator
or change alternator attachemnt point to allow larger alternator or install another bracket for a second alternator. But I hear that a second alternator can sometimes place too much pressure on engine bearings. I have done step 1. For step 2 I think I will install a second alternator
