Over Charging 169
 

I was having a hard starting issue where the starter didn’t want to turn over. I did some checking and cleaned everything up. The connections were very dirty and corroded. After cleaning the connections the starter works great.

I then wanted to verify the system is charging ok. With the Key off I have 13.2 volts at the battery. I started the battery and it jumped to over 100 volts. I thought maybe my volt meter was bad so I did some other checking and then rechecked and sure enough the voltage was very high. Turned it off and the voltage went back down to 13.2.

I did an ohms test from the F terminal on the generator to ground and it buzzed so there is connectivity there. I thought maybe there was a problem with either the voltage regulator, or maybe the wiring so I disconnected the F terminal from the voltage regulator and did the same test. Still buzzed, so I then disconnected the wire from the F terminal on the generator and did the same test. It buzzed again.

I wanted to confirm, there should not be continuity from the F terminal on the generator to ground. From what I understand that is how you test the charging system is to ground the F terminal, so it sounds like I may have an internal short in my starter generator? Just want some thoughts before I tore it all down when it may not be needed.

Any ideas are greatly appreciated.

Thanks

Dave

IF you had a 100 Volts going to the battery, I would imagine that it would get hot and blow up. PLUS, every electrical thing on the tractor would burn up too.

Are you sure you are measuring this right...???:HeadScratch:

Ya, make sure you are measuring correctly. The starter generator field circuit is grounded through the regulator. If you remove "f" terminal and the output remains high, then the problem is in the s/g. Accidental internal grounding of the field circuit will prevent normal regulation,= excess output. The s/g should not put out more than 15 amps.

I totaly agree guys, 100 volts seems extreamly high and i thought there would have been damage done to others. I agree that maybe the multimeter is off. I had the multimeter on DCV for DC Volts, originaly on 20, which after I started the tractor it said 1 to the far left which means off scale. I turned it up to the next scale which is 200 and it said around 100. Which I thought was crazy. I dont have a meter that measures amps so I cant say for sure. The dash amp meter was maxed out but swaying, with it being the original meter I would only use it as a general value and not rely on that alone.

Regardless it appears that the generator is being internaly grounded if there is continuity between the F terminal and ground. I guess I need to tear into the starter/gen and see whats going on. Hopefully nothing is toast.

I am going to tear it apart today and will post what I find.

Thanks guys, just wanted to make sure I understood the charging circuit correctly.

Wanted to get pictures. If course the running voltage didnt get up to 100 like I said but I also didnt want to run it full throtle as I know this cant be good to run like this. Regardless check out the photos below.
One picture is the tractor off and the other is of it running with the F terminal disconnected from the starter/gen.

I am going out now to take off the starter/generator and see whats going on.

Did you note any noise comming from the s/g.? If you need more info., see Delco Remy Service Bulletin IMG-150. I only have part of this manual, as my printer crapped out. Wild Bill gave a note on where to have repairs made: Automotive Armature Works, Inc. 105 W. High St. in Piqua, Ohio 45317. Sooner than later, I will be asking the same questions myself. Hope you get it squared around! Thanks, John

There is no noise or any type signs coming from anything. Its weird, the only reason I found this was because of the hard starting issue, and wanted to make sure the charging system was functioning properly. I should have an update shortly.

Hope this helps. Now, let the experts show you the way! Dog-gon it! Have a nice exploded view of the s/g and parts lists, but no pictures came up.

Got it taken off and apart. Everything looks ok from a visual inspection, no burning or broken terminals on the inside. Carbon is all over the place but thats expected since this is the original far as I know.

After taking it apart I did a little testing, between the F terminal and the case I checked for continuity and there is none. That is where I thought the problem would have been. I checked between the F terminal and the Gen terminal and there is continuity.

I guess at this point since there is nothing obvious I am going to review the documents I have on the starter generator and see what else I can check while I have it apart.

After looking everything over and reading over the starter generator documents it looks like I may have a bad commutator. Also given that I dont have the proper tools to check the various areas of the starter/generator, I guess I will need to take it into a repair shop. This would explain why when the generator is apart I dont have continuity between the F terminal and the case, but when I put the commutator in it shows a ground between the F terminal and ground.

If anyone has some time I have a few questions maybe someone could check with a good functioning tractor.

With the F terminal disconnected from the Generator do you have continuity between the F terminal and ground?

With both terminals diconnected from the Generator do you have continuity between the two terminals?

here's a test.
Hook a 12v bulb or test light to the battery terminals,check the brightness,start the motor and see if the bulb gets brighter or burns out,if not something is up with your meter.

Found some interesting details.

The Starter/Generator can be tested the following way:
Resistance testing I have the following values
F Terminal to Case ~8 ohms
Gen Terminal to Case ~ 0.5 ohms
F Terminal to Gen Terminal ~ 8 ohms

From what I was able to find these are within allowable values. I then cleaned everything lubed and put it back together. Got it on the tractor and hooked up the gen terminal only and left the F terminal disconnected. Started the tractor and again the multimeter went to a high voltage. Looking at the amp gauge it showed discharge. I then hooked up the F terminal while it was running and it sparked a little and the rpm dropped. The amp gauge went positive.

So at this point I think the starting and the charging system is functioning properly. I think the multimeter is giving bad readings. I am going to get another multimeter and do some further testing. At this point if the voltage was indeed around 100 volts like the meter is saying I would think the light bulbs would blow but they are functioning just fine.

Dark, I agree I think the meter is a fluke and not in the brand name meaing lol. I think its giving bad readings for what ever reason. A friend gave it to me for free so who knows its story.

Thanks everyone for the help.

Your meter is TOAST...

If you were getting 100 VDC, it would burn your Ignition Coil up and then you would have nothing. The fact that the tractor starts indicates the voltage is in the "ball park:".

Totaly agree, kind of annoying that a meter would send me in a wild goose chase, but atleast I learned a little, and got the starter/generator cleaned out. The other meter I have is one of the cheepies from Harbor Freight. I think i need to invest in a better one with the electrical I am constantly doing around the house. Would be nice to have one that does inductive amperage. I guess thats nother topic altogether.

An alternator will run voltage up in the range you measured if it is unregulated and without diodes to produce DC current, but you do not have a modified alternator.
A generator by nature produces DC current and will not produce voltage in that range.
you would be lucky to see 18 DC volts.
A battery should if fully charged, read about 12.6 volts after 12-24 hours resting period.
Actually, a inexpensive throw away harbor freight type tester works pretty good in most applications.
You are not building a electronic circuit, just checking ball park readings.
I agree it sounds like you have a malfunctioning multimeter