Convert Alternator to Internal Regulator (L1500 / 175)

billrigsby · Sep 23, 2016

I am wondering if any one has done the conversion to get rid of the old external regulator on a L175 or 1500 or similar?

I think I have the wiring figured out, but maybe someone well versed in auto electrics can confirm.
The following is the stock wiring with regulator;

And this is what I think will work using a 3-wire alternator;

Any thoughts from an auto electric expert?
Any idea what alternator will "bolt up" to the 175 / 1500 engine, before I do a lot of leg work?

Thanks, Bill

Tooljunkie · Sep 23, 2016

Putting the cart before the horse, an awful lot of planning before aquiring the alternator. They are configured differently in how they energize and trigger the warning lamp. You have the idea,but for instance a gm internally regulated alternator will auto energize at 1000 rpms. Some indicators feed positive,others ground.

Finding the necessary wiring diagram for almost any alternator is easy.

North Idaho Wolfman · Sep 23, 2016

Post a picture of the alternator you have already on it.

billrigsby · Sep 23, 2016

North Idaho Wolfman said:
Post a picture of the alternator you have already on it.

This is what is on it now, a Nippondenso 021000-2550.....

Not visible in the picture but there are two mounting tabs on the bottom,
here is a picture of an aftermarket or rebuilt one.....

josh64 · Dec 15, 2017

Did you get any further with this?

My external regulator has died and I'm having trouble finding a replacement, so I thought replacing the alternator with one that has an internal regulator would be a reasonable course of action.

billrigsby · Dec 16, 2017

josh64 said:
Did you get any further with this?

No, unfortunately I have not.
I did not think the old externals were hard to get,
This is for the L175,
should work on the L1500 also.

Kubota: REGULATOR

Part Number 70000-65398
Vendor Kubota
Messick's Price $33.51
Stock Quantity 6
Weight 0.80 lbs
Days to Order In stock
Replaces 33251-74012, 33251-74010, 33251-74013

Part Number 33251-74012

The part fits the 8 models listed below:
GV-3240SW
KH-18L
KH-60H
KH-90H
L175
L285P
L285WP (Wid row application)
M4000

lugbolt · Dec 17, 2017

Tooljunkie said:
Putting the cart before the horse, an awful lot of planning before aquiring the alternator. They are configured differently in how they energize and trigger the warning lamp. You have the idea,but for instance a gm internally regulated alternator will auto energize at 1000 rpms. Some indicators feed positive,others ground.

Finding the necessary wiring diagram for almost any alternator is easy.

Not all of the Gm alternators will. The one wire is more like 5000 (alternator speed). The 10SI is lower. The CS series is lower yet, and MUCH more efficient than the old 10 and 12 SI's.

Personally I'd drop in a Denso 40A internally regulated unit and be done with it. Easy to do. You'll need the 3 wire version, which has a 2 pin plug and a main charging lug that goes to the battery. Instructions are everywhere on which of the 2 pins does what. They are a very common alternator on various Kubota tractors, mowers, etc and they bolt right onto the bracketry in most instances. I just put one on my G1900 last year and did away with the Dynamo. Although the dynamo is extremely reliable, the wiring that comes on the G series is sub par, and since mine was poorer than "normal", I went ahead and swapped on a 40A Denso alternator. They're about $50 if you look around, but if you buy a new one from Kubota, about 10x that much. Should be able to utilize the wires from the regulator to energize the alternator and also to make the charge indicator light work.

The aftermarket alternators seem to be ok, however, the factory one (which is a geniune Denso) lasts nearly forever as long as it isn't run underwater.

josh64 · Dec 20, 2017

lugbolt said:
Personally I'd drop in a Denso 40A internally regulated unit and be done with it. Easy to do. You'll need the 3 wire version, which has a 2 pin plug and a main charging lug that goes to the battery. Instructions are everywhere on which of the 2 pins does what.

OK thanks I might try that because getting an external regulator here in Australia is about half the cost of an 40A alternator and I'm pretty sure the current alternator needs an overhaul too.

I have got the wiring diagrams (including billrigsby's excellent one) and I have been wanting to replace all of the wiring anyway.

josh64 · Aug 25, 2018

I got an alternator with an internal regulator. Over the next few weeks I'll be wiring it up and hopefully provide some good news in an update!

In Utopia · Aug 26, 2018

Save yourself a lot of headache and get one of these.
It's a direct bolt on replacement and only uses 1 wire.
Put one on my L175 earlier this year, only took about 1/2 hour to do.
There are other versions that are cheaper.
Hot rodders are using these or similar.
Cranked it up, and at idle it puts out 14.6volts because it's self exciting.

https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=331348989514&_sacat=0

MilkyWay · Aug 26, 2018

In Utopia said:
.... Cranked it up, and at idle it puts out 14.6volts because it's self exciting.

I'm pretty much self exciting too!

josh64 · Aug 28, 2018

In Utopia said:
Save yourself a lot of headache and get one of these.
It's a direct bolt on replacement and only uses 1 wire.
Put one on my L175 earlier this year, only took about 1/2 hour to do.
There are other versions that are cheaper.
Hot rodders are using these or similar.
Cranked it up, and at idle it puts out 14.6volts because it's self exciting.

https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=331348989514&_sacat=0

I wanted to redo the electrics anyway as the indicators stopped working a while back... If this alternator doesn't work I'll look at doing what you did. Did you keep the external regulator?

In Utopia · Aug 28, 2018

josh64 said:
I wanted to redo the electrics anyway as the indicators stopped working a while back... If this alternator doesn't work I'll look at doing what you did. Did you keep the external regulator?

No, there was no reason to keep it.
I didn't remove it, just unplugged the wiring that went to the old one.
I did however add a digital volt meter instead of trying to get the old light system to work again.

josh64 · Sep 7, 2018

Well I have the alternator mounted and wired in, but I'm only getting ~ 12.8 V across the battery. So I guess it isn't getting turned on.

My charge lamp isn't lighting up so I'm going to check the continuity on that as well as my IG lead.

josh64 · Sep 7, 2018

Well, I got it all working! Showing ~14.4V across the battery now when idling at what looks to be around 800rpm (but not sure how accurate the tachometer is!).

Special thanks to billrigsby whose wiring diagrams were invaluable!

OrangeColoredTractor · Sep 8, 2018

billrigsby said:
I am wondering if any one has done the conversion to get rid of the old external regulator on a L175 or 1500 or similar?

I think I have the wiring figured out, but maybe someone well versed in auto electrics can confirm.
And this is what I think will work using a 3-wire alternator;
Any idea what alternator will "bolt up" to the 175 / 1500 engine, before I do a lot of leg work?

Thanks, Bill

Bill, I was really an expert on these, its been almost 30 years, but all fresh in my head. You conversion is dead on. I think its a great upgrade also.
Has your original system failed?

OrangeColoredTractor · Sep 8, 2018

OrangeColoredTractor said:
Bill, I was really an expert on these, its been almost 30 years, but all fresh in my head. You conversion is dead on. I think its a great upgrade also.
Has your original system failed?

Caution on self exiting, they usually use a small "leak" resistor to tickle the rotor (field) to get it going and will drain batterys if they set a while and Kubotas do set sometimes. Most alternators that are internally regulated can self excite just based on the small amount of residual magnetism, but sometimes requires a high rpm to do it.

The Denso common plug on those compact internal fan Denso type is basically a 3 pin plug, one will be L, IG and S or light, ignition and sense. The sense, if you want can hook to alternator battery terminal at the alternator, (assuming no voltage drops to battery and there shouldnt be) IG is that, 12V with ignition on. Compact fan models do not use a diode trio, therefor, this circuit doenst produce a counter voltage to cancel a light like the GM 10/12/15SI, it is controlled by a transistor inside the regulator and once charging, the TR just opens the path to ground, thus, turning off the light. The IG terminal is 12V ignition with key on. The GM CS series works the same was the Denso internal fan type does. The Denso external fan internally regulated alternators do use a diode trio and the L terminal will produce a counter voltage. But on those models, you only need either L or IG, it will excite with one. The only reason they used IG in addition to the light, was in case the charge lamp bulb burnt out, it had a backup to excite the field, a burnt bulb is basically an open circuit at that point.

South 40 · May 4, 2022

Hey Folks, I know this thread is almost as old as I am, buttt....

I want to convert my L1500DT to a IR Alt, and all I see her is dead links to Ebay, can somaone actually post a good known Manufacture/Part number that will replace this old Denso ER 021000-255XX I have now?

Thanks
Samantha

jellyhead · Sep 17, 2024

In Utopia said:
Save yourself a lot of headache and get one of these.
It's a direct bolt on replacement and only uses 1 wire.
Put one on my L175 earlier this year, only took about 1/2 hour to do.
There are other versions that are cheaper.
Hot rodders are using these or similar.
Cranked it up, and at idle it puts out 14.6volts because it's self exciting.

https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=331348989514&_sacat=0

Can you please post the part number for this alternator?

fried1765 · Sep 17, 2024

jellyhead said:
Can you please post the part number for this alternator?

"In Utopia" post was SIX years ago.
A response is not likely!

Convert Alternator to Internal Regulator (L1500 / 175)

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