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Discussion Starter #1 (Edited)
Would a bad regulator / rectifier do this?

Would a bad rectifier / regulator cause fluctuation in DC voltage while idling?

I have an Onan P216 and the voltmeter goes up and down as it pleases causing the headlamps to get brighter and then dimmer (12-16+ volts).

Its charging, but if that signals rectifier I will replace. If it is something more like the stator I will have to save up for it to fix it. Since its charging, I dont think it would be the stator. Since its not STEADY voltage only varying a little when I up the throttle I would think it is the rectifier.

Please tell me if I am wrong. I can find all about testing the charging system in general, but nothing about fluctuating voltage and its driving me nuts.

Any help is appreciated guys! I dont want to fry it.
 

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Sounds more like a ground issue to me. Get teh schematic for you machine and test all the grounds. Any resistance on any of them should be investigated.
 

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Discussion Starter #3
I tested yesterday at the battery while it was not running with the new battery. It read 12.76 volts. 13.8 running at idle.
I tested it with it running at full throttle and it was a steady 16.75 volts and decreased as the engine throttle decreased and increased as the engine throttle was increased.
 

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Discussion Starter #5 (Edited)
Sounds norm to me...
But wouldnt a continual barrage of 16.75 volts at the battery fry it in a short amount of time?

I always assumed (of course you know what they say about ***-U-ME, lol!) that the charging system would put just a little bit more juice back into the battery than was used, and that extra bit was for running accessories such as lights and such while replentishing the battery of energy used to start it and the total being around 13.8-14.5 volts. With the volt meter itself jumping around, but the voltage steadily going up with engine RPM had/has me worried.

I dont mind buying a battery or two until I get it fixed if something is wrong with it, but dont want it to fry the entire charging system with voltages approaching light welding current and have to spend a mint to get it running again. Of course I dont want to worry about it if there is nothing wrong with it at all. Thats just as bad as doing nothing while you know something is wrong.:thThumbsU
 

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something ain't right. 13.8 to 14 is where it should be. It'll boil the batt dry if you don't watch it......
 

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Discussion Starter #7
If I run it at half throttle it seems to run where it is supposed to at 12-14 volts in general. Only when running above half throttle does it jump and go up to 16 volts. (So far the highest it has gone is 16.76 volts at the battery while running full throttle.)

Would replacing the regulator on top of the Onan be the best place to start?:confused:
 

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Yep, thats where I'd start. I had to replace the reg on the onan that was in my new holland skid steer a few years back. It was a P218. There are places that rebuild those, thats what I put on mine. They have them on ebay right now at buy now 24.30
 

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Discussion Starter #9
Thanks man. Im going to do just that. If its not the problem, it will at least be new. If it is, it will fix the problem.

One other stupid question. I tried to get the old one off by taking off the single bolt and lifting it off. Is there something else I have to do to get the old one off? I mean is there double sided tape under there or do I have to partially remove a shroud that I am just not seeing?
I know the one on there is the original because it has the smokey colored "gel" on top facing outward.
 

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Just the one on mine. Probably just stuck over the years or something. I sent you an email with an ebay addy that has one in it I found.
 

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Discussion Starter #11
Just the one on mine. Probably just stuck over the years or something. I sent you an email with an ebay addy that has one in it I found.
Thanks Toolman....I literally just purchased it after confirming it was the one for my engine. Should be here in a few days and we will see. Thanks again. That was a nice price for what I was finding the other day. I guess it just depends on what order you punch in the words or when you check.:thThumbsU
 

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I just googled onan voltage reg, an that ebay listing came up about 3 or 4 down the page. I'll bet that fixs yer problem feller....:fing32:
 

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I also think the regulator will fix your problem. A regulator is suppose to do what it implies, maintain or regulate voltage to a specified voltage. When the voltage starts to vary going up and down fluxuating with load then the regulator is defective. The voltage can vary a little but the readings you are getting are out of whack.
 

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Discussion Starter #14 (Edited)
Yuppers....that was the problem. A little over twenty bucks and it saved my battery from cooking. Runs better, more steady and I dont have to worry about a new battery in a few weeks (again), lol!

13 volts at idle and 14 when at hight throttle.

I love it when a plan comes together!
 

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Glad you got that problem solved!!:thThumbsU

Two other things come to mind when searching out the 'wiremites' in these older Wheelhorses--the regulator (rectefyer) has to be grounded good--and check the two or three pronged black plastic plug that slips onto the regulator for corrosion-or burn spots......

I have just had both happen re-wireing a C-120A.
I know--different engine/ but same electrical principles....:crybaby:

glenn
 

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Discussion Starter #16
Gotcha Glenn. I did check to see if the old one was grounded good, took it off, cleaned the area and reinstalled it nice and tight. Didnt make a difference at all. No burns anywhere on the contacts OR the smokey colored resin. No plastic connector either, just spade connections.

I think it was just its time to go to the great wiring harness in the sky. Either that or the pidgeon poop was conductive and maybe gradually shorted it out......Im suprised it didnt eat through the metal.
 
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