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hdtvluvr
11-01-2009, 03:13 PM
I have an old JD 111 mower that I re-powered with a 12 HP B&S engine about 2 years ago. When I installed the engine I replaced the stator to a higher output one since the mower has an electric PTO.

At 3300 rpm it puts out 17.6 volts with the PTO off. With the PTO on I get 15.3 volts. I use this mower mostly for pulling a garden cart. Therefore, most of the time it is outputting 17.6 volts. The mower has a diode to convert AC to DC. This too was replaced when I installed the new engine.

I know this high voltage is bad on batteries. What can I do about it? Should I get a regulator?

Using my meter set to 30 and AC, it read 0.15 volts with PTO off.

unkownfl
11-01-2009, 05:26 PM
check with a different meter. .15 should be 15 volts when converted.

hdtvluvr
11-01-2009, 05:41 PM
The 0.15 volts was AC across the battery terminals. From what I understand, I shouldn't get an AC reading - but 0.15 is extremely small and may be an invalid reading.

I'm not sure what " .15 should be 15 volts when converted" means.

unkownfl
11-01-2009, 09:47 PM
Sorry I thought you had a old meter where you select the max voltage. First take it to your outlet in your house and make sure it is correct it is not uncommon for them not to be. Once you have checked tell me what size diode you have and Ill need you to take some readings and give me the results.

hdtvluvr
11-01-2009, 11:44 PM
My meter is a digital Radio Shack model. One does have to select a max voltage (3, 30, 300, etc.) by turning a knob. It has another knob to select ohms, AC, DC, etc. Using the meter on house current, I get 120V with the setting on 300.

But given I selected 30 as the max voltage, .15 is well below 30.

I can't tell you the size of the diode. It is John Deere part # AM38783. It is inside heatshrink tubing and appears to be approx. 3/8 inches long by 1/8 inch wide. I know this isn't the "size" you are looking for but it is all I know.

Since I am getting a DC reading on the battery side of the diode, isn't the diode OK?

unkownfl
11-01-2009, 11:50 PM
Yes the diode sounds to be fine, but you said you changed the stator so that would mean a different diode could be needed. They have different sizes.

hdtvluvr
11-02-2009, 12:25 AM
I purchased the diode and stator at the same time. I hope they sold me the correct one.

The wire on the original diode had been "repaired" a few times. I'm not sure why it needed repairing since I got the 111 used from my father in law.

hdtvluvr
11-02-2009, 09:07 AM
Yes the diode sounds to be fine, but you said you changed the stator so that would mean a different diode could be needed. They have different sizes.

Since the diode is wired between the stator and battery circuit, doesn't it just allow flow of electricity 1 way and make the current DC? In order to regulate voltage wouldn't it have to be connected to ground somehow in order to dump the excess voltage?

unkownfl
11-02-2009, 10:18 AM
However diodes can have more complicated behavior than this simple on-off action, due to their complex non-linear electrical characteristics, which varies with the construction of their P-N junction. These are exploited in special purpose diodes that perform many different functions. Diodes are used to regulate voltage (Zener diodes), electronically tune radio and TV receivers (varactor diodes), generate radio frequency oscillations (tunnel diodes), and produce light (light emitting diodes).

Restrorob
11-02-2009, 10:20 AM
How many wires are coming off this stator ?

What color are these wires ?

What color is the plug connector on the end of these wires ?

Lastly, What's the engine model and type numbers ?

hdtvluvr
11-02-2009, 09:36 PM
How many wires are coming off this stator ?

1

What color are these wires ?[/QUOTE]

Black

What color is the plug connector on the end of these wires ?

Green

Lastly, What's the engine model and type numbers ?

B&S 12 HP
Model 284707
Type 1026-E1
Code 030618ZE

hdtvluvr
11-02-2009, 09:57 PM
The engine originally came with a dual circuit alternator. I swapped it out with a #696457 alternator which is either 5 or 9 amp output. I do not know which output I have.

Restrorob
11-02-2009, 10:47 PM
You installed a Tri circuit stator;


http://i107.photobucket.com/albums/m314/Restrorob/Briggs/BriggsTriCircuitStator2.jpg


It would be my guess since the wiring has been butchered you have a diode problem, Briggs list a replacement diode harness part# 691955 @ $37.75....

For that kind of money you could go back to the dual circuit since you don't mow with the unit and call it a day.....

hdtvluvr
11-02-2009, 11:02 PM
I thought the stator I used could be a 5 or 9 amp (depends on magnet size) or used as a tri-circuit.

When I got the stator, I also got a new diode. It is a single wire on both sides of the diode. John Deere part # AM38783

I do use the mower a few times a year to cut grass in an area with a lot of trees so I really need the charging capability to work with and without using the PTO. I've now cooked my second battery since the engine swap.

Restrorob
11-03-2009, 07:35 PM
Well,

You need to double check your tractor numbers and make sure you got the right diode.

According to JDparts:

AM37977 diode for s/n up to 120000
AM38237 diode for s/n 120001-190000 (includes diode and connector)
AM38783 diode for s/n 190001-
Also stators:
AM37976 for s/n up to 120000 (includes diode)
AM38310 for s/n 120001- (includes connector)

I don't know why they have 3 different diodes listed, but that's what they show.

Just wondering, Why didn't you swap the stator from the old engine ? To my knowledge they haven't changed over the years.....

hdtvluvr
11-03-2009, 09:09 PM
Based on your parts info and the S/N from my tractor (222xxx) what I used agrees.

My diode is AM38783 which I got from a John Deere dealer along with the stator part #. They wanted too much for the AM38310 stator so I thought I'd use the old one. This stator cross-referenced to a Briggs 691065 which had been replaced by #696457 according to everything I found.

The original engine's stator had a black wire and green connector. After pulling the flywheel and seeing all of the dirt that had accumulated and packed into the windings and thinking about the stator being about 25 years old, I thought it would be best to get a new one since the replacement engine was brand new. So I ordered a 696457 online.

I talked to my father in law today and he told me that he replaced a lot of batteries on it too but never knew why. He isn't into troubleshooting/tinkering. Therefore, I guess it has always cooked batteries. Well, now I am buying the batteries and would like for them to last longer :) - especially since this mower isn't used on a weekly basis.

My conclusion is that since this is a mower, JD assumed the PTO would be on most of the time and utilizing some of the voltage leaving only a slightly high excess to charge the battery. As stated before, I get 15.3 volts across the battery with the PTO on.

Now since I use it mostly without the PTO, I would like to regulate the voltage but am unsure how to accomplish this. Any ideas?

The stator that came on the new engine was a dual circuit with 1 black and 1 red wire.

Restrorob
11-03-2009, 09:40 PM
Yeah, I did all the part number crossing as well but didn't have the tractor serial number.

There is a way to get this thing working, You can add the tri-circuit regulator;


http://i107.photobucket.com/albums/m314/Restrorob/Briggs/BriggsTriCircuitStatorRegulator.jpg


Here's the part# and price for the regulator; http://www.briggsandstratton.com/maint_repair/repair_parts/index.aspx?_dp=1&pno=691188

hdtvluvr
11-03-2009, 09:49 PM
THANKS!!!

The text says it is a regulator-rectifier so I can remove the diode from the circuit - correct?

I'll let you know how well it works when I get it and install it.

BTW, based on the #'s I posted above can you tell whether the engine has small, medium or large magnets? I wonder whether this stator puts out 5 or 9 amps. Just curious.

Restrorob
11-03-2009, 11:55 PM
The text says it is a regulator-rectifier so I can remove the diode from the circuit - correct?


No, Do NOT remove the diode yet. As in the first pic I posted above it shows a diode to keep battery voltage from feeding back into the stator and blowing it.

The same may apply for the regulator, It's been a while since I worked on this tri-circuit system. Make sure the regulator is grounded good, They normally mount to the engine block near the starter or dipstick tube.

Plug the stator to the regulator then start the engine, Put your meter on the red output lead and see if you have DC voltage output. If so test the diode lead that will plug into the red regulator wire, If this diode is good you will get no DC voltage on this plug with the key either off or on. If this is the case plug the diode harness to the regulator then test run checking DC voltage output at the battery.

BTW, based on the #'s I posted above can you tell whether the engine has small, medium or large magnets?


Naaa, Because there is no tri-circuit stator listed for your engine numbers. Flywheels are not denoted by magnet size only part numbers per model and type numbers.

hdtvluvr
11-04-2009, 10:51 AM
I really appreciate your help. By knowing what to look for I was able to find the info below. Based on analysis of the text, it seems the diode harness will not be needed. If I had found this sooner, I would have known to add the regulator #491546 (which is now 691188(

Also, (found in the same document) since my engine came with a dual circuit, by changing to the Tri-circuit stator it would seem that my system is a 5 amp.

I'll let you know how everything wortks when I get the parts and install them.

Thanks for everything.

hdtvluvr
11-04-2009, 11:02 AM
Text modified for clarification:

I really appreciate your help. By knowing what to look for I was able to find the info below. Based on analysis of the text, it seems the diode harness will not be needed. Especially item 6 stating that if the original system had a 5 amp regulated circuit (meaning that a regulator was installed) one can discard the diode with the new engine. If I had found this sooner, I would have also known to add the regulator #491546 (which is now 691188)

Also, (found in the same document) since my engine came with a dual circuit (meaning small magnets), by changing to the Tri-circuit stator it would seem that my system is a 5 amp (also small magnets).

I'll let you know how everything wortks when I get the parts and install them.

Thanks for everything.

hdtvluvr
11-07-2009, 06:44 PM
Got everything installed today. The output now is 13.5 - 13.6 volts with the PTO on and off.

Now maybe I can get more life out of my batteries. Thanks again!

Restrorob
11-07-2009, 07:03 PM
Thanks for the thread up-date...... http://www.xtremesystems.org/forums/images/smilies/thumbsup.gif