Dynamo - B7001 - low voltage - what to do?

[pmwoody]

Hi,

I have owned a B7001 tractor from 1977.
Its in very good shape and the engine runs perfect.
The dealer put in a new battery - so in the beginning no problems at all in the beginning.

Now the battery was getting weak. I measured 12.1V.
I charged the battary with a charger - 14V - the battery is back again (13.2V) and everything works fine. The Battery is ok.

When I measure the battery with running engine on max RPM and full lights on etc. The Voltage is sinking below 12.4V and is sinking slowly as it is typically with lights etc on.
The Battery is not charging. But i can see a bit variation in the voltage at different RPMs.

So I measured in AC the Dynamo. Its only 7-12,9V comming out of the dynamo depending on the RPM.

I think 50% from the Stator is damaged. Does anyone ever rebuild a stator for such a dynamo? How are the stator coils wired? Does anyone has technical data for this?

I can't find a spare part here in Germany - so the only laternative would be shipping from the US at some dealtes I found the right spare part 15372-64290.

Thanks for all comments and help.

Best regards,
Mario

 

[Breeze]

There have been discussions of this on the site over this issue. Using the Search function for your issue I located this thread which should be helpful:

http://www.orangetractortalks.com/forums/showthread.php?t=8167&highlight=alternator+replacement

The General Motors alternator discussed should be available in Germany

 

[pmwoody]

Hi Breeze

There have been discussions of this on the site over this issue. Using the Search function for your issue I located this thread which should be helpful:
[...] The General Motors alternator discussed should be available in Germany

Thanks for your information.

I would like to keep the original dynamo since the tractor should be more or less in original as possible. Changing the dynamo to an alternator is easily possible - but not the target

I searched before - but i could not find information for the stator replacement or stator repair in the dynamo.


Best reg.
MArio


P.S. sorry for my poor english.....

 

[50shootr]

Hi.. My b6100d had same problem,clean all connections in charging system,I pushed a large needle wire probe along the wire clear plastic wire sleevesand spray with a penetrating oil and carefully pull the leads apart,do this up to the voltage reg. , run another ground lead from the volt reg ground to batt ground,when you take the elec conn apart don't pull on the wires, use pliers and clamp where the wire is crimped to the terminal and wiggle it apart.,the volt reg can be tested - diodes , stator, both with a ohm meter . I cleaned my wireing, I get 5 amps, 13.8 v at fast idle.,assuming the dealer didn't reverse the batt leads when installing the batt and blowing the diodes in volt reg , good connections make a big difference . Ed

 

[pmwoody]

Hi 50shootr

yes - you're right - the cables are very important. I have to clean them - that's true.

But my problem is already before the voltage regulator. It's only 50% of the ususal voltage comming out of the dynamo. So i have no idea if from the 8 coils in the Stator are 1, 2 or even 4 broken since the output is only half of the expected output......

BTW:
Is the dynamo from the B6000 the same ad from the old type B7001?

Thanks again for any input.


Best reg.
Mario

 

[50shootr]

Hi..My original problem mainly was low voltage from the stator,it was the corroded bullet connectors where it was crimped,assuming yours is clean,only thing left is to replace stator/dynamo, I 'm new to kubota,I'm a marine mechanic by trade.,maybe someone knows the output test, ohm s ck,I don't have a manuel. Ed

 

[pmwoody]

Hi 50shootr

thanks. I measured the resistance of the coils yesterday. I have 0,4 Ohm - so its looked ok.

I measured directly at the dynamo - and magic -> between white and brown cable I have the expected 14-30V. From my point of view white and brown should be somewhere at the regulator than - but its not.....

So there's a problem somewhere between the dynamo and the regulator. I have the follow each cable and will see where the failure is.

The dealer put "German" lights on the tractor to get the TüV approval. The wires are a desaster. I will have to renew it I guess.

Best reg.
Mario

 

[pmwoody]

Me again,

I measured all cable and found a very strange thing.....

From the dynamo.....
White and Yellow end up at the light switch. Brown is going directly in the Regulator.
Between white and brown I have voll 14-30V AC. From the light switch a cable in read is going to the regulator.

What the hell is the "G1" "G2" and "S" on the light switch?????
In all wirediagrams I cant find anything - these are always emtpy and the dyamo goes directly into the regulator. Not on my tractor......

It looks that after the light switch the problems starts and no AC is comming into the regulator. Before the light switch I have 14-30V.

Does anyone know the function of the light switch in reg. of the AC support for the regulator?

Thanks a lot.

Best reg.
Mario

 

[kubotasam]

Their are 2 types of dynamos. A 2 wire where the AC current goes directly to the rectifier and gets changed into DC current to charge the battery. The second type of dynamo has 3 wires coming out. I don't have my service manuals in front of me so I can't tell you exactly what color wires do what but I have this all figured out at home. The 3 wire dynamos use a portion of the light switch to control how much charge is put out. When you turn on the lights it changes to a higher charging rate. The light switch is actually 2 switches in one. When you turn on the lights it operates both sets of contacts.
I also have a copy of the 3 wire dynamo wiring diagram at home. I think I remember seeing a copy posted here, I will look.

 

[kubotasam]

You can find the wiring diagram for a 3 wire dynamo system on a B7100 by searching "82 B7100 positive ground" Service Dept Vic has a link to the diagram that you need. I am fairly sure your B7001 is the same as a B7100. Remember to think of the light switch as 2 separate switches operated by one lever. The G1 G2 and S terminals control the high low charge.

 

[pmwoody]

Hi kubotasam,

thanks a lot. Yes - the wiring diagram is exactly like my B7001.

In the meantime I'm sure that the dynamo is ok. Up to 35V on 2800RPM and on the "low voltage" loading approx. 25V.

Out of the regulator, I only get something below 12,5V max - so it looks that the regulator is broken. I ordered a new one and I will see if this will fix the problem.

Thanks to you all for your help.


Best reg.
Mario

 

[kubotab7001]

Hello,

I've been having the same issue as pmwoody, seems I've got the same setup on my b7001, wires from the reg through the light switch.

I have tested the generator and that is all good, there were melted wires coming from the regulator which I have replaced but I'm still not getting th 14v charge from it.

I ordered a new reg, but it doesnt have the same wires out (black/blue/red-white/blue). Existing is (red/red/blue/white).

Does anyone have the wiring diagram or link to correct reg that would be a great help. ps. I searched "82 B7100 positive ground" but couldnt find anything- old thread I guess.

Thanks

 

[Dave_eng]

Need to go back to some basic questions.

Your tractor uses a Dynamo to produce power for charging the battery.

The Dynamo produces Alternating Current which is then rectified to charge the battery.

Some early B series dynamos had 3 output wires. Most had just two wires.

How many wires are coming out of your dynamo?

Some early tractor used Alternating Current from the dynamo to power the lighting.

You need to use an electrical meter capable of measuring Alternating Current.

Disconnect all output wires from the dynamo. Connect the electrical meter to two of the wires. Run tractor at full rpm's and measure the voltage. If your dynamo has three output wires, do the test on pairs of the output wires. Three tests will be needed.

Does your tractor have a warning light to indicate when the battery is not charging?

It is likely you have a rectifier/regulator for a different model of tractor.

Never heard of a positive ground Kubota. My Nuffield 465 had + ground but I converted it

Once you reply I will go further.

Dave

 

[kubotasam]

Hello,

I've been having the same issue as pmwoody, seems I've got the same setup on my b7001, wires from the reg through the light switch.

I have tested the generator and that is all good, there were melted wires coming from the regulator which I have replaced but I'm still not getting th 14v charge from it.

I ordered a new reg, but it doesnt have the same wires out (black/blue/red-white/blue). Existing is (red/red/blue/white).

Does anyone have the wiring diagram or link to correct reg that would be a great help. ps. I searched "82 B7100 positive ground" but couldnt find anything- old thread I guess.

Thanks

Here is link to that post.https://www.orangetractortalks.com/forums/showthread.php?t=1037&highlight=b7100+positive+ground

 

[Dave_eng]

I have attached a wiring diagram for a B6000 with a 3 wire dynamo.

This is why I asked a number of questions from the guy with the problem because it makes a big difference which dynamo you have.

If you take the time to study the marked up diagram note the pink and yellow colored wires going from the dynamo to the light switch without passing through the rectifier. The lights on this tractor are running on alternating current and this is why a LED conversion does not work on this model. LED's need direct current.

The yellow wire leaves the light switch and goes back to the rectifier. The blue wire goes from the dynamo to the rectifier. This provides the rectifier with two AC leads which it can rectify to DC in order to charge the battery.

The last image of a 3 wire dynamo is from a John Deere.

Dave

 

[kubotab7001]

Thanks for the replies,

My tractor does have the 3 wire generator and it tests good straight off it, problem seems to be once it reaches the reg.

The wiring is exactlly that of the diagrams you posted.

I cant find the exact reg, the one i purchased was listed for b7100 so obviously not everything's the same on these two models.

I there a way to wire up the one I've got, even if that means bypassing the lights?

 

[GreensvilleJay]

re: LED's need direct current.

Not really true.. I've run them on AC for decades for my 'self indicating SSRs' using a few, simple extra parts.
Hoover, the vacuum guys, used a Red/Grn LED on AC as it'll glow org/yel when power is applied.

 

[Dave_eng]

re: LED's need direct current.

Not really true.. I've run them on AC for decades for my 'self indicating SSRs' using a few, simple extra parts.
Hoover, the vacuum guys, used a Red/Grn LED on AC as it'll glow org/yel when power is applied.

Search this forum. Owners of 3 wire dynamo's who tried LED lighting reported back that they did not work.

Yes an electronic style diode will glow when connected to AC, after all, that is how the LED lighting originated.

If you put a diode bridge before the LED lighting then it will work but few have the skills to do that.

Dave

 

[Dave_eng]

Thanks for the replies,

My tractor does have the 3 wire generator and it tests good straight off it, problem seems to be once it reaches the reg.

The wiring is exactlly that of the diagrams you posted.

I cant find the exact reg, the one i purchased was listed for b7100 so obviously not everything's the same on these two models.

I there a way to wire up the one I've got, even if that means bypassing the lights?

Can you post a link to the rectifier you bought.

How many wires on your new rectifier?

I will help you get the new unit working if you have some patience.

You need to get the lighting working which will prove the 3 wire dynamo is generating power.

Disconnect the wire I have marked in green which runs from the light switch to the rectifier. Then run the machine and try the lights.

The simple aspect of your system is that the lighting is independent of the rectifier.

Dave

 

[kubotab7001]

Thanks Dave,

https://www.ebay.co.uk/itm/12V-Volt...tor-B7100D-B7100HST-D-B7100HSTE-/181882287967

This is the unit I've got, three wires and a ground,

I'd appreciate any help you can offer, will test the machine tomorrow.