DC alternator conversion

munson1086 · Nov 27, 2012

Hi everyone,

I have been making slow progress on my 53 DC. The whole time and money thing always gets in the way!! I just finished installing a new rubber seat spring last weekend.. what a difference! It's amazing; the seat had been welded solid for as long as I can remember. My next project I want to start on is new wiring, lights, and alternator.

Soooo.... yet another question on the 12v conversion. I have read a bunch of material on this topic.. but still have a question. I have a DC with magneto and I want to keep the mag.. so distributor is not an option. Here is where my question is... do I need to install a separate ignition switch for the wire that goes to the #1 terminal on the alternator? I plan on installing the delco 10 si alternator. If anyone has a wiring diagram with a tractor with mag and alternator that would be great!

Thanks,

Matt

Case Nutty 1660 · Nov 27, 2012

my starter repair guy builds me ones with a slow speed regulator and they are also aone wire unit so all you have to do is hook up a battery wire and you are good to go and it will kick in and charge at around 600 alt rpms they work very good on these slower speed engines cnt

Bob in Australia · Nov 27, 2012

I have done a similar conversion on LA.

I used a normally open oil pressure switch to excite the alternator.
That way, no extra ignition switch is needed. It is similar to the
conversion on diesel tractors.

D G Wells · Nov 27, 2012

Bob in Australia, That is a great idea!! I had been looking for a good way to make the connection automatic. I have a switch on the gage panel but I cannot always trust myself to turn it off. I put one of the small alternators and a step-up pulley on my Case LA and it works good so an oil pressure switch would a be good step up. Thanks for that idea from the Land Down Under. We really enjoyed the people in and around Sydney and Kiama.---Derrol in Texas---

souNdguy · Nov 27, 2012

why not just use a diode and make it automagic.. no extra switch.. etc.?

mEl · Nov 27, 2012

(quoted from post at 18:43:04 11/27/12) why not just use a diode and make it automagic.. no extra switch.. etc.?

Soundguy, he wants to keep his mag so there will be no 12V source like there would be if the unit was battery ignition equipped. normally a diode between the 12V coil post and the alt would be the ticket I agree and have done many.

The D10AC regulator that the other poster referred to in the 10SI Delco is the real ticket, I have an 830 Diesel with one on and it charges 30A at just above Idle and is charging as soon as the engine starts. This regulator requires the removal of the diode trio and wiring added internal to the alt to work, but work it does.

mEl

souNdguy · Nov 28, 2012

i didn't miss the fact he wants to stay magneto ignition. there are plenty of ways to skin this cat without an extra switch.. etc.

so.. is the machine hand crank? or push start?

it has no button to engage an electric starter solenoid.. even a manual one?

got headlamps?

lotsa options I can think of on a diesel or mag ignition unit.

i'm not a fan of 1 wire units. generally cost more and may take igher rpms to excite.. and some have high quiescent leakage when not running.

munson1086 · Nov 28, 2012

Hi everyone,

Thanks for the info! So I'm guessing my assumption is correct, I would need some sort of 'ignition switch'. The tractor will have lights (once rewired and fixed) and does have electric start - but not a key switch. It was my understanding that all DC's has the starter button under the dash and gauges? It seems like all the conversion articles deal with tractors that have a distributor - and thus an 'ignition switch'.

Bob - do you have a part number or a picture of the open oil pressure switch? Sounds like a great idea. Perhaps if i did use a ignition 'switch' I could wire in a warning light like are on the Diesels... reminder to turn the switch off. That's how I always remembered to turn the keys of on our 30's series tractors.

Matt

4435 · Nov 28, 2012

I don't want to hijack the thread here. Has anyone found or used a smaller diameter alternator versus the 10SI. I am using the OE belt and find that on the 51 DC I keep hitting it with the chicken roost. Thanks Tom

Roger S · Nov 28, 2012

Wire it like this. Hook up the 10 gauge wire to the amp meter(terminal that battery isn"t connected to), and the 18 gauge wire to the oil pressure switch,(terminal that battery isn"t connected to). The amp meter should be close to the alternator output amps. They made the delco alternators as low as 37 and 42 amps, but are harder to find. If you are using a 20 amp meter on the tractor keep the engine idled down as much as possible if the meter pegs.

Bob in Australia · Nov 28, 2012

I bought several on ebay. Had to have them posted here from the
US. Just search normally open pressures switch.

They were a few dollars each. I looked at the proper Hobbs switches
but they were over $50 each here and I have had them fail in the
past, so I thought I would try the cheap ones. So far they are OK.

munson1086 · Nov 28, 2012

Thanks everyone.

Roger - will I still need the diode?? I'm thinking the oil pressure switch will be all i need?? Sorry for all the questions!

Matt

Roger S · Nov 28, 2012

I would put a diode, or resistor, or you could use a 194 bulb,(works like a charging light on cars). That terminal grounds when the engine is shut off, and supplies 12 volts when the alternator is charging. The short time the engine is shutting down, especially in cold weather, the oil pressure can take a while to lower enough to shut the oil pressure switch off, but the alternator has quit charging. It will act like a direct short for a short time. I have burnt out the contacts in the oil pressure switch by not having something in there to take the load for that short period of time.

munson1086 · Nov 30, 2012

Hi everyone,

Ok- here is the wiring diagram that I drew up during our morning staff meeting... important things first!! Am I on the right path here??

Sorry for the messy diagram.

Matt

DC alternator conversion

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