D650 dynamo thingy

solwisestsve · Aug 28, 2007

Okay... first post

I have a B6001 which has the D650 engine. I've been trying to check if the charging system is working but having problems trying to understand exactly what is what (the circuit diagram doesn't match what I have).

There is some form of generator on the nose where the fan is. This has three wires coming out; brown, white, yellow. I also have a regulator/rectifier which has 5 wires (can't remember the colours but, ISTR, there are two reds, a white and a blue). The white wire was broken but I've reconnected it to permanent +12V. I have no charging light so I guess I have a dynamo.

Now the problem is the voltage at the battery, with the engine running seems to be too low :-( I'm seeing about 12.7 volts which would tend to suggest a very low charge. The feed from the rectifier (or it could be a regulator) coming out of the white wire shows about 0.3 to 0.4 Amps with engine running and no other electrical load. If I turn the headlights on I see 2.3Amps coming from the rectifier. BTW the battery is freshly charged.

Can anyone please advise what the heck I have here?
i.e. is this a dynamo?
What should be present on the 3 wires from the dynamo?
Do I have a rectifier or a regulator and how should it be wired?
Also, what sort or charging voltage should I have with a fully charged battery?

Sorry for so many questions but I've spent several hours on this so far with very little advancement

Thanks in advance for all advice.

Steve

(Kubota virgin)

Egon · Aug 28, 2007

I have a parts list for my B7100 HST that also has diagrams. If you feel this would be helpful please send me your email address and I will send it to you.

KubotainNH · Aug 28, 2007

I'm pretty sure it's a dynamo. If so the voltage coming out at low rpm's is pretty low. Crank the rpms up and you should see around 13volts if I remember correctly. I attached the schematic for my b6100, yours may be similar. It's a little blurry but if you download it you can zoom in more.

solwisestsve · Aug 29, 2007

Thanks this is much more like what I have... not 100% the same but very close. I seem to have a white wire that goes from the regulator back to the permanent live but yours is red. I also can't figure out why the diagram shows a white wire from the generator to the light switch but your light switch is different.

So, can I please ask, what sort of voltage do you see on the battery with the engine reving?

I've measuered mine at low and high rpm and it still only shows about 12.7V. However, I see the current from the regulator to permannent live (Red on your diagramm but white on my vehicle) is c. 0.4Amps with no load and rises to about 2.3Amps with the lights on. This would tend to suggest that the regulator is sending out a tricle charge normally but does increase the current/power output dependant upon load (e.g. rises when the lights go on).

In antisipation... thanks

KubotainNH · Aug 29, 2007

It may take me a day or 2 to get time and measure the voltage on mine. Hopefully the anticipation doesn't eat you up.

solwisestsve · Aug 30, 2007

In antisipation... thanks

I might have doen enough checking to satisfy myself that it IS charging but, any measurments you can supply would hopefully re-enforce this

Did a big measuering session last night. Measuered volts (on the battery) and amps (coming out of the +ve terminal). This is what I found...

At rest vehicle off: 12.48V 0A
Ignition on but engine not running (but oil warning light is on): 12.45V 0.23A
Ignition on but engine not running with lights on : 12.29V 2.27A

So the above shows that current is certianly flowing out of the battery when the engine is NOT running. Then I started her up...

No lights etc.. on: 12.61V -1.55A
(i.e. current is now flowing the other way and into the battery)
Now with the lights on: 12.66V -1.60A

Looks like I certainly have some current going into the battery when the engine is running. I just wonder if 12.6V is enough to charge the battery? Didn't I read somewhere that you need at least 2.15V per cell to charge a lead/acid battery? That would say 12.9V. However that assumes the battery is delivering the normal 2.15V per cell. Mine seems to be doing 12.45V at rest (only 2.07V per cell) so maybe 12.6V charging is enough as a tricle charge?

Egon · Aug 30, 2007

Check the battery with a hydrometer for a more accurate indication of the battery condition. [ If its possible on your battery]

solwisestsve · Aug 30, 2007

Wilco...

Now where is that hydrometer? Not used one for about a decade so might have to pop along to the local motor factors to get one

cityfarma · Aug 30, 2007

From my recollection, a dynamo gives out DC while an alternator gives out AC which is rectified inside the alternator and sends DC to the battery.

Voltage is regulated by varying the current into the field windings on both types. If the load is light, the field current is low. If the load increases, the voltage drops and more current is fed into the field winding to bring the voltage back.

A fully charged battery after being left standing for say 24 hrs, will read around 13v to 13.5v. If the voltage is read straight after charging or with the engine running at moderate speed, the voltage would be around 14v.

When the engine is off and lights on, the voltage on a good battery with good terminal connections should read around 12.5 to 13v. If the engine is started, it should rise to 13.5 to 14v.

Measure the voltage while starting the motor. The voltge should drop to 9 to 10v while cranking.

If these voltages don't agree with what you are getting, check the terminal posts and cables are clean. If they are clean, you may have a faulty battery.

Can you measure the current in the field winding? You can locate the wire by disconnecting a cable (obviously not the one going to the battery!!) and the voltge will drop and no charge should go to the battery. The current should go from the regulator into the field winding and increase with load.

You may also have a faulty regulator. You can test the generator/alternator by bypassing the regulator and feed the field winding through a lamp to limit the current. Try various lamps to get one that allows sufficient current through. The voltage from the gen/alt should increase as you feed more current into the field winding.

Cityfarma

solwisestsve · Aug 30, 2007

Sounds like my battery is pants then :-(

It's probably been in store in Japan for a few months and then on a boat an then in store in the UK for a few months so not unexpected.

I'll contact the supplier and get him to sort it.

Thanks for the pointers.

Steve

cityfarma · Aug 30, 2007

My previous comments where made not knowing the age of the tractor. They still apply but I would add that any generation device on a car/truck/tractor etc in the last 20yrs is more than likely to be an alternator as they are far smaller and efficient.

Cityfarma

solwisestsve · Aug 30, 2007

Age??? Who knows? ;-)

It's a referb. B6001. Anyone know when the B6001's were made? I'm going to guess at least 20 years old.

The generator has three wires going from it so that might meen it's a very small alternator. There's no traditional 'charging' light but I suppose it's possible this role could be controlled by the rectifier.

cityfarma · Aug 30, 2007

It may be a relay type regulator. They have two relays that (from memory) control voltage and current.

The voltage coil contacts are normally closed with the engine stopped. When the engine is started, current is applied to the field. The gen/alt then produces voltage and the relay operates if higher than the set voltage. This stops current flowing in the field and the voltage drops. This releases the relay and current flows again. The result is that the relay buzzes when regulating the voltage.

The current regulator is similar except that the gen/alt current flows through the coil of the relay. If the current exceeds the set current, the relay operates and cuts the current to the field. It also buzzes if the current is too high.

The regulation is adjusted by changing the distance that the contact arm is away from the relay pole. If the distance is greater, the higher the voltage or current required to operate the relay.

If you can post a picture of the gen/alt and regulator, it may be possible to identify it.

Cityfarma

KubotainNH · Aug 30, 2007

I just got the volt meter out to measure my B6100. The thing actually fluctuates alot. When off I read 12.46. After starting it the voltage actually drops but then after about a minute it starts to rise. At half throttle it started at 12.9v and rose to 14.5. Drop it back to idle and it drops down to 13v and keeps dropping depending on how low it is idling. High idle runs about 12.85. I've had the tractor for a couple years and never had an issue with a dead battery even if it sat for a month. The same battery is still in it from when I bought it. There's some pictures of mine on this post: http://www.tractorbynet.com/forums/kubota-owning-operating/70830-b6100-picture-3.html#post1208547 If it looks similar then it's most likely a dynamo.

solwisestsve · Sep 6, 2007

Sorry for the late reply... Been too busy of late.
Well your readings are exactly what I'd expect but, unfortunately, are NOT what I get :-(
Looks like I'm going to have to do some more stripping down and tracing :-( TBH just so blasted busy at the moment that it will just have to wait - sounds like a winter job ;-)

Thanks for your readings though, if nothing else they've confirmed I have something wrong.

I'll use the curcuit diagrame (previous post) and give it a good trace down and measure to try and find out exactly what's to blame - I just hope it's something easy to replace/fix.

On a similar note. I was looking around and I wonder if it would be possible to fit a very small car sourced alternator in the spot where the belt adjuster sits? Then I could rip out the recitfier and start from scratch with something more modern and that I understamnd a lot better

cityfarma · Sep 6, 2007

If you source an alternator and (inbuilt?) regulator you should be able to replace the generator. The interesting part would be fitting it.

Cityfarma

KubotainNH · Sep 6, 2007

I think it has been done and posted here for other models. Try the search function. Some models have a Kubota kit to upgrade it but no idea if this one does.

David_Kb7uns · Sep 8, 2007

The dynamo on my BX2230 put out AC current. The Kubota dynamo uses a magnet where the alternator that i replaced the dyanmo with uses a field that has a regulator to change its strength. They both put out AC current where a Generator puts out just DC. If you look at some of the schematics for the Kubota tractors the rectifier will send half of the AC wave to the lights and the other half is regulated for charging the battery, this is similar scheme done with the dual circuit charging on Briggs engines for riding lawn mowers.
David