L3600 not charging

[Tony Wells]

Greetings all!
New guy here, having a small problem with a L3600. Guilty of letting it sit for maybe 3 months, and went to use it, and no start. Simple enough, battery charger on low....no hurry. Refused to charge. Dash lights came up, died on crank position. OK, low battery even after ample charge time. Checked all connections, make and break with cleaning. Didn't like the smallish braided Gnd cable (I do heavy equipment repair) so replaced with a larger cable to frame. No change. Battery measures about 10V+ a smidge. That tells me a cell is bad, being they are two volts each, conducts enough to charge, and not shorted. But current isn't supported at 10V, so drops to nada when cranking. Sounds simple enough. But the ignition switch was acting a bit flaky, hit or miss even trying, and I didn't like that, so replaced it with OEM. The flaky went away, but still needed a battery, so put one on. Now it will start and run normally, but the battery light stays on. Checking V at alternator battery terminal confirms that it isn't charging. 40A fuse on alternator line is good, as all the rest. I would like an explanation of the 2 position plug on the alternator. Which wire, which function.

Two things; I need a diagram, which I cannot seem to find. And any tips on testing the ND alternator or regulator. I have a shop that rebuilds that sort of thing, but before I pull it, I would think there would be some diagnostics possible.

And one more thing. The ign switch, even though I picked up from a reputable dealer, of course just plugs into the harness behind the instrument cluster. Is it safe to assume that there are no variations of the switch that could be the culprit? I don't really think so, but can't ignore the possibility.

Thanks for any help you experts can provide!
t

 

[old and tired]

Look up L3300 which might give you some help (nothing for L3600).

Index of Kubotabooks/Tractor Parts Manuals/

 

[Roadworthy]

Start by charging your battery with the charger then have it load tested. If your charger can't put on an adequate charge your tractor won't charge it either.

 

[Tony Wells]

Look up L3300 which might give you some help (nothing for L3600).

Index of Kubotabooks/Tractor Parts Manuals/

old and tired, thanks. At that page, which I had visited before, I saw no help on the 3600, so at your suggestion, looked for the 3300. Only the owners manual, which has no technical data on the electrical system. I did find a service manual on Scribd, however. I had forgotten I had a membership there. I have what I need as far as a schematic.

 

[Tony Wells]

Start by charging your battery with the charger then have it load tested. If your charger can't put on an adequate charge your tractor won't charge it either.

Roadworthy, my charger is more than capable, but that's a moot point now. I replaced the battery after a load test anyway. I am needing to test the charging circuit, and now I have the schematic, so hopefully can sort it out.
Thank you!

 

[Hkb82]

sorry missed a bunch of the first stupid me.

 

[Tony Wells]

Add what you think may be helpful. I'm just looking for answers. I pulled the alternator yesterday and opened it up, cleaned the slip rings and brushes, but had no specs on checking the regulator or anything else. Still a little curious about the switch. Part of this problem is that everything was fine until I let it sit a while. It was charging normally and always started easily. Battery went down and would not take a charge, and a new battery and ign switch was changed. Now the battery light stays on. Seems odd.

 

[Russell King]

Since you have no schematic to go with I would suggest you see how much voltage is across the battery terminals in the non running and then the running conditions. That would give you an idea if the alternator is doing anything or not. I suspect it is not working properly since the charge light stays on.

But then I have little to suggest than take alternator off and to a shop for repair or replacement. I have no clue if that tractor has a internal or external regulator but glancing through the illustrated parts list it appears to be internal so I’m pretty certain that if it’s repaired or replaced then a should be good, unless there is some fuse that is blown that is not energizing the alternator.

Perhaps the repair shop can tell you what to test before removing it?

 

[Tony Wells]

Since you have no schematic to go with I would suggest you see how much voltage is across the battery terminals in the non running and then the running conditions. That would give you an idea if the alternator is doing anything or not. I suspect it is not working properly since the charge light stays on.

But then I have little to suggest than take alternator off and to a shop for repair or replacement. I have no clue if that tractor has a internal or external regulator but glancing through the illustrated parts list it appears to be internal so I’m pretty certain that if it’s repaired or replaced then a should be good, unless there is some fuse that is blown that is not energizing the alternator.

Perhaps the repair shop can tell you what to test before removing it?

Russell, the regulator is screwed in place on the end of the alternator, as are the diodes (bridge). I did find the service manual, and there is a test procedure for the components. The regulator is tested simply just like a diode; it should conduct in one direction but not the other. The diode bridge, also held in place with screws, is also tested that way, just one diode at a time. It has to be removed to be checked. The windings all come out of the stator and are wrapped under the screws that hold it (5 IIRC) so I haven't wanted to pull the bridge yet. The wires are solid and my experience says they won't tolerate much flexing.

I have checked the voltage with it running, and all I see is battery voltage where I want to see somewhere over 13.0-13.5 or a bit more. The alternator is not making juice. That tells me the light should be on as it is, so I am looking for why, exactly. If I can't find it, I'll take it to my electric shop and see if they can pinpoint it, and either fix it if it's the bridge or regulator, or I'm stuck buying another alternator. Just can't see what changed while I was not using it.

 

[Hkb82]

I think if you have 13.5 or higher at the battery with it running your alt is working. Maybe just that it’s weak??? not pushing it over 14v keeps your dash light on possibly??? You could put a battery charger with boosting capability on well tractor is running. Put ya over the 14v hump and see if the light goes out. I’d maybe also try putting the old ignition back in now that you have a new battery. Seems odd to get alt issues from letting your battery die or drain over time. You sound like ya heave a good understanding of the system so I’m sure your gonna find the culprit

 

[Tony Wells]

I think if you have 13.5 or higher at the battery with it running your alt is working. Maybe just that it’s weak??? not pushing it over 14v keeps your dash light on possibly??? You could put a battery charger with boosting capability on well tractor is running. Put ya over the 14v hump and see if the light goes out. I’d maybe also try putting the old ignition back in now that you have a new battery. Seems odd to get alt issues from letting your battery die or drain over time. You sound like ya heave a good understanding of the system so I’m sure your gonna find the culprit

I am not getting more than battery voltage. I wish I was getting the 13.0+ at the battery. But then, if the light was still on I'd have to track that down. I haven't had time to look at it much over the last couple of days. I can hook the charger up and see if that puts the light out. I'm not sure what the threshold voltage is where the light goes out.

The manual describes a primary test of the system by jumpering the B+ terminal to the IG terminal and disconnecting the neg battery terminal and checking the alternator output. Should be ~14V. That's my next step. The regulator in this case is a solid state/IC device that uses a transistor to switch the light on or off, depending on it's bias. If the charge voltage is not present, the transistor supplies battery voltage to the lamp, which is always grounded on one side, so it lights. If the charge voltage is present, the transistor switches open and stops supplying current to the light, extinguishing it. That's the normal operation. (with neg connected, and running) So my thinking is that either the regulator is faulty and never switching the current off to the light, or the alternator is bad. If I check the voltage with the jumper in place, and it is correct but the light is still on, that transistor (in the regulator) is bad and I'll replace the regulator. I suppose that in the diode bridge, which functions to rectify or change the AC that the alternator actually supplies, to DC, there could be a bad diode(s) which would probably kill the voltage that switches that transistor. Can't charge a battery with AC. I can check to see if the output (assuming anything is there) is AC or DC. That would tell me about the diodes. Next test if necessary.

 

[Hkb82]

Sorry I though you were getting over 13v I’m betting your alt isn’t working and was likely the reason your batt was drained. I don’t think 3 months is a super long time to sit but if your alt was on its way out for the last couple times you used the tractor then it would make sense. Not sure how hard it is to pull the alt out but I have a feeling from the sounds of it that’s it. Definitely some people on here that are going to know your L 3600 way better than me. I’ve never even touched one lol

 

[Tony Wells]

Sorry I though you were getting over 13v I’m betting your alt isn’t working and was likely the reason your batt was drained. I don’t think 3 months is a super long time to sit but if your alt was on its way out for the last couple times you used the tractor then it would make sense. Not sure how hard it is to pull the alt out but I have a feeling from the sounds of it that’s it. Definitely some people on here that are going to know your L 3600 way better than me. I’ve never even touched one lol

It's an easy pull. Side panel, 2 bolts and three wires. We are supposed to get some rain the next day or two so I'll have time to look at it. The battery was getting some age on it, so I suspect it just died and stayed dead. I was really surprised when the new battery showed not charging, but since I also replaced the ignition switch, which is what energizes the field coils, I am wondering if I got the correct switch. I got it from a legit Kubota dealer, so I am assuming so at this point. The shop manual has a contact chart, but I haven't gone through it to verify that it matches though. There are only 3 wires on it, so unless at assembly someone made an incorrect connection (there are more than 3 terminals on the switch), I'm confident it's the right one.

 

[Tony Wells]

Just to close this out, I found the rotor windings open in the alternator. I didn't bother to see if I could repair it. Bought a new alternator and all is well.

 

[Hkb82]

I had a feeling it was your alternator lol. Glad you got it figured out and can put it back to work.