Kubota B6100 Dynamo Testing

[Matt S]

So I'm back on this task again and I'd appreciate any help you can offer. I have some new info though. The problem is that the battery doesn't charge and the lights and horn does not work. When I connect jumper cables to my car everything works fine.

1) When I take the battery out of the tractor and charge it off my car it seems to charge, but once I disconnect it and let the battery stand the voltage drops from about 12V down to about 3V in an hour

2) When I measure the voltage at the battery from the dynamo it's about 4V. At this point the tractor is at full throttle and the lights are off. I don't know how to test the rectifier or the output of the dynamo itself.

Can anyone tell me what the voltage should be at the battery terminals when the tractor is running (13V dc like a car?)? Or maybe how to test the dynamo and rectifier?

Thank you for your help.

Matt

 

[zman007007]

Hi Matt, just as you would check your car, it should read between 12.5 to 13.5 accross your battery terminals. I have a b7100HST and it also was not charging when I bought it. Like you said I could charge the battery and leave the volt meter on the battery while it was running and you could see the volts dropping as it ran. Someone had put a jackleg switch on mine with a push button also. I took all that off, and bought the right switch for it. Then i took off the dash panel from around the steering wheel and chased all my wiring down and corrected what was wrong, and it has charged fine since then. I hope this helps you. I think yours is supposed to be similar to mine. If you need a wiring diagram let me know. zman

 

[zman007007]

Also are you sure the battery is good? If not you should have it tested.

 

[mitch becton]

have you tried to charge the battery check the system and see if the out put at pos post on dynamo is as stated before 12.5 to 13.5 and will maintain this out put. there is a electrical term known as leaking diodes these are in the rectifier these will always be one way diodes meaning the power is going through the system and being used up and not intended to go back in the direction they came from when this does happen over a period of time it will drain down the battery the dynamo will appear to be good but actually is a hidden theif. if by some chance you have a major wiring problem and the draw is coming from there you can always by a battery selector switch that will allow you to kill the power to you tractor every time you shut it off. hope this helps.

mitch becton

 

[zman007007]

I guess we will never know the answer Mitch. lol zman

 

[TODD G]

Matt
You need to connect an AC volt meter to the two wires coming out of the dynamo it should read 20 to 24 volts AC if it does the dynamo is good and regulator is bad and shold be replaced

 

[Matt S]

Thank you everyone for the great responses. Basically I was measuring little voltage at the battery. Yesterday I took the hood off, cleaned the engine, than took the ground wire off the battery and disconnected it from the frame, where it met the frame was really corroded, I cleaned up and re-assembled. Suddenly I could measure 18-19v at the battery? I was like WTF? hahaha

I wonder if disconnecting the lights and reconnecting did it? Or making sure the ground was good? What do you think?

Thank you,

Matt

 

[mitch becton]

bad ground connections are the most overlooked problem with electrical systems because you dont think of them because with any repair most often you only disconnect the pos side at the battery and if you do starter or alternator work basically all you disconnect is the pos side hook ups.

good luck

mitch becton

 

[Matt S]

The ground connection was really bad, the screw was tight but where the end met the frame it was very rusted and corroded. Took me a while to get it clean, hopefully that's all it was.

Matt

 

[MikesTractor]

Glad you found the problem. As said before, that is a commonly overlooked prblem. What I like to do where the ground meets the frame, after taking the cable loose I take my side grinder and lightly clean off the area to good metal. Then I clean the battery cable end (or replace the cable) and put some battery cable grease on the frame and cable before bolting them together. I forget what it is called, but it is a red grease in a big can (about a quart size) that has a brush inside the lid. I can't read the label anymore, but it is made for battery cable ends.

Oh well......there I go rambling again...

Mike