B7200 charging problems.

[Tchara]

I've been reading several posts on the Infamous Kubota charging system, and I seem to be coming away with more questions then answers. I just recently bought the tractor, and knew there was an electrical problem, since the guy told me, he always disconnected the battery when he didn't use it. I purchased a new dynamo and rectifier and installed them. As I did, I noticed the yellow, and brown wire of the rectifier harness melted and fused together in the plug. I cut the wires at the plug and and spliced them together to bypass the plug. I'm getting 30VAC at the dynamo, but only 12.5 DC at the battery.

I read that if you have a 3 wire dynamo, the light switch is part of the charging circuit. Mine is a 2 wire. The lights are not there, but the light harness is. Does the 2 wire dynamo include the light switch in the charging circuit.
There isn't any separate wire going to the battery to charge it. Does the charging circuit charge through the starter wires?

Also the rectifier I purchased had a ground wire attached. The one I replaced does not. Should I use the ground wire on the new one.

Thanks in advance for any help you can give.

 

[GreensvilleJay]

yes, you need the ground wire connected.
would need to see a good wiring diagram of your tractor but you've confirmed dynamo is putting out 30VAC so that part seems fine....
if the 'rectifier' only has 4 leads, I'll assume 2 go to the dynamo, a big red will be the +V going to the battery +ve terminal, and of course the ground wire.Typically these units are very simple inside,couple diodes, SCR, zener, 1-2 resistors and control up to 15 amps of power are based on a B&S patent from the mid 70s.

 

[Dave_eng]

I've been reading several posts on the Infamous Kubota charging system, and I seem to be coming away with more questions then answers. I just recently bought the tractor, and knew there was an electrical problem, since the guy told me, he always disconnected the battery when he didn't use it. I purchased a new dynamo and rectifier and installed them. As I did, I noticed the yellow, and brown wire of the rectifier harness melted and fused together in the plug. I cut the wires at the plug and and spliced them together to bypass the plug. I'm getting 30VAC at the dynamo, but only 12.5 DC at the battery.

I read that if you have a 3 wire dynamo, the light switch is part of the charging circuit. Mine is a 2 wire. The lights are not there, but the light harness is. Does the 2 wire dynamo include the light switch in the charging circuit.
There isn't any separate wire going to the battery to charge it. Does the charging circuit charge through the starter wires?

Also the rectifier I purchased had a ground wire attached. The one I replaced does not. Should I use the ground wire on the new one.

Thanks in advance for any help you can give.

I am going to send you by private conversation my email address.
Please send me photos of the rectifier,t top of the battery and starter terminals
The output of the rectifier would go to the main battery terminal on the starter not to the battery.
Where did you buy the new parts? If you can please provide a link to the site.
Your tractor should have a fusible link, likely green, at the starter. Check that one is there and the wire of the link is smooth and without any bubbles.

The fusible link is an early form of slow blow fuse. It is there to protect the entire wiring harness.
The fact that you can have wire terminals melt concerns me as it may indicate the fusible link has been removed and not replaced but jumped.

Dave

 

[Tchara]

I am going to send you by private conversation my email address.
Please send me photos of the rectifier,t top of the battery and starter terminals
The output of the rectifier would go to the main battery terminal on the starter not to the battery.
Where did you buy the new parts? If you can please provide a link to the site.
Your tractor should have a fusible link, likely green, at the starter. Check that one is there and the wire of the link is smooth and without any bubbles.

View attachment 113364
View attachment 113361

View attachment 113362
View attachment 113363
The fusible link is an early form of slow blow fuse. It is there to protect the entire wiring harness.
The fact that you can have wire terminals melt concerns me as it may indicate the fusible link has been removed and not replaced but jumped.

Dave

Thanks for your input and information. I purchased the rectifier and dynamo as a set from Amazon.
I also bought a new battery, since the old one was 2017.....ouch...sticker shock.
I'll look in to the fuseible link. I am aware of therm and was looking for a fuse in the wiring, but neglected to see if the fusible link is on the starter.

I'll send pictures you requested as soon as I am able.
Thanks again.

 

[Tchara]

Thanks for your input and information. I purchased the rectifier and dynamo as a set from Amazon.
I also bought a new battery, since the old one was 2017.....ouch...sticker shock.
I'll look in to the fuseible link. I am aware of therm and was looking for a fuse in the wiring, but neglected to see if the fusible link is on the starter.

I'll send pictures you requested as soon as I am able.
Thanks again.

I got the idiot lights and charging system figured out. It was a fuse holder in the headlight harness that was corroded. I replaced it with a new inline fuse and holder. Dave told me to check the fusible link at the starter. I did, and there isn't one. I bought a heavy duty fuse holder, but not sure if I should use a 25 amp fuse, or a fusible wire link. Can a fusible link be substituted with an in line fuse?

 

[Dave_eng]

I got the idiot lights and charging system figured out. It was a fuse holder in the headlight harness that was corroded. I replaced it with a new inline fuse and holder. Dave told me to check the fusible link at the starter. I did, and there isn't one. I bought a heavy duty fuse holder, but not sure if I should use a 25 amp fuse, or a fusible wire link. Can a fusible link be substituted with an in line fuse?

More modern tractors use a SLO BLOW fuse instead of a fusible link.
The performance issue is that the circuit needs to tolerate an overload for a short time before blowing. Regular fuses cannot do that.
The Slo Blow fuses are readily available. However, the holder is hard to find as it is part of the vehicle and rarely needs replacement so suppliers dont carry them.

Typical Kubota fusible links are Green which is 40 amp.
The slo blow fuse follows the same color convention.

Try a Google search for Busman fuse catalogue. It may put you on the track for the fuse holder. However, check local auto supply places first as my knowledge is out of date

Dave