Charge Light on Dim on a L185

[OldGrayOwl]

I have a L185 and the charge light is on fairly dim at idle, and it gets brighter the higher the RPMs are.
At idle, I am reading 15 volts DC, and at full throttle, I am reading 18.5 volts.
At full throttle, the light is at its brightest, but not as bright as it could be like when the engine is off, and the key switch is on.

I have tried different regulators, as well as another alternator.
The results are the same.

It is a new battery.

Any thoughts or ideas?

Thanks,

 

[twomany]

Sounds like a diode going bad. But one would think changing the regulator would take care of that.

Is there a Zener stack on that model?

 

[Rosher18]

I mentioned this in another thread a few months ago. Similar voltage readings and symptoms on my L185DT. I was told the voltage regulator might be going bad, but I haven't done anything to it since.

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[Dave_eng]

The voltage readings you have provided are not representative of a properly working system.

Could two things be happening, your multi meter has been dropped one time too many and you have a charging system problem?

The fact that the issues did not change when you switched components complicates matters.

Do you have an owners' manual with a wiring diagram you could post?
Dave M7040

 

[OldGrayOwl]

I borrowed a calibrated meter from where I work, so it isn't a problem with my instrumentation. I am an Electronic Technician by trade (40+ years), so I know how to handle metering.
I do not have any wiring diagram or schematic for the system, as I just got this tractor rather recently.
I am thinking that it 'might' be a bad battery ground, as I was looking at it tonight, it looks rather shaky. I am going to do a voltage drop test from the minus side of the battery and chassis ground. That might be giving a false feedback and boosting the battery voltage.
I really don't know, that's why I'm here.

 

[Russell King]

I have a owner manual that I can email to you if you want. Just send a PM or post your email address (make it look bad like Russellking(at) austin( dot) rr (dot) com ) so bots can't see it.
I believe it has a wiring diagram.
But these tractors are bad about cable and ground points going wonky.
I would start with cleaning all battery connection points and the ground point really well. Maybe just replace the cables or use jumper cables to eliminate them...


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[Dave_eng]

Old Gray.....

Your technician knowledge will be invaluable is solving this situation.

Usually it is a guy who does not have any knowledge at all when it comes to circuits who is here with complicated electrical problems.

If Russell King's manual has a wiring diagram plse post it here in as much detail as you can.

Some early Kubotas had charging circuits completely foreign to those of use who grew up and learned in North American. While the alternator/dynamo has thee phase output, only one phase would be rectified to DC to charge the battery. The other two AC legs went to the light switch and then the lights as AC completely independent of the battery.

If the alternator and charging system on your L185 is more advanced than those early ones, then, as everyone is suggesting, poor circuits with high resistance are where the trouble likely is.

The alternator has to get a voltage signal back to it so it can adjust its output voltage to meet the battery's needs. It also needs to get a "turn on," signal which is usually done through the warning light. You have described that the warning light operates correctly when the engine is not running and the key in the ON position which would be to be illuminated brightly?

Could you post some pictures of the side of your engine and also of the components you had swapped out and of the fuse box.

A completely new ground battery cable is a good investment with factory ends not repair clamps. If the ground cable connects to the frame, install a second cable from that point to somewhere on the engine block. If the ground path has high impedance, everything will be wonky.

Dave M7040

 

[Russell King]

Manual sent to both Dave and Old Gray Owl
Let me know here if it did NOT get through

I know Dave received it


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[Dave_eng]

Old Gray....

Rec'd the manual from Russell and am studying it.

Since you are suspecting the ground cable I am a strong advocate of replacing it with new cable with factory ends. If the ground cable does not go to the engine block, I would buy another short cable with two eye ends on it and connect it from where the ground cable attaches to the engine block.

Make certain that the regulator has a good ground and also the dynamo.

For the regulator to work properly, it has to receive a good strong voltage signal which is representative of the state of charge of the battery.

The following is from a 2012 post:

"Re: L1501/L185 Charging Light Woes
I just thought I would give you guys an update of my charging light problem which today has been solved. Some may benefit if a similar issue arose.

As luck would have it, my hours/rev counter cable snapped a short while back and today I having been sent a replacement from the dealer (under warranty) I set about fitting it. The whole dash came off for this which meant I was able to get access to some electrics that I hadn't previously.

In short, I took off the voltage regulator, cleaned the contacts in the plug and then took the regulator cover off. I cleaned all the contct points (rather like the contact points in an old petrol engine) inside with a fine abrasive.

I cleaned every single bullet connection and removed all the wires from from the ignition/light switch and fuse box and cleaned up all the contacts with a fine abrasive.

I put everything back together, fired her up and hey presto - charging light went out.

Now, I had cleaned all the wire connections before but the only thing I hadn't touched was the voltage regulator.
If any of you get a similar problem and your alternator is providing an adequate charge then it may be wise to take the regulator apart and simply clean the contacts in side. You'll save money into the bargain.

I wonder how many regulators have been discarded when all they need was a spring clean.

All the best guys from a very happy Spanish farmer.

Gary"

Dave M7040

 

[85Hokie]

I have a L185 and the charge light is on fairly dim at idle, and it gets brighter the higher the RPMs are.
At idle, I am reading 15 volts DC, and at full throttle, I am reading 18.5 volts.
At full throttle, the light is at its brightest, but not as bright as it could be like when the engine is off, and the key switch is on.

I have tried different regulators, as well as another alternator.
The results are the same.

It is a new battery.

Any thoughts or ideas?

Thanks,

a bad ground will force a alternator to charge at a higher rate than it should.
As others have mentioned -
Replace leads and see if anything changes.

 

[Russell King]

Old gray
Manual sent again


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[OldGrayOwl]

Thanks for the manual. Even though I only got part of it, I got enough info, I think.

What I have done is to add a ground directly to the regulator from the alternator, as well as from the alternator directly to chassis ground. No change.
I checked the continuity of the wiring from the alternator to the regulator, and all is good. I cleaned the connectors with contact cleaner to remove all of the dirt and grime.
I installed a heavy wire directly from the negative terminal of the battery to the case of the alternator.
I am borrowing a known good alternator.
I installed a new regulator, after trying the regulator from my old, non-working L175.

I STILL have a dim charge light lit, and when the tractor is running, my metering is showing 17.9 volts.

I noticed that when I switch off the main switch (which disconnects the alternator and regulator), the engine speed increases slightly. When I switch the main switch back on, the engine speed drops slightly. The alternator is getting warm when it is operating.

The F (field) terminal on the alternator reads 17.9 volts, the N terminal reads 9.2 volts, and the E terminal (I am guessing that this means earth), reads 0 volts. The B terminal (Battery) reads 17.9 volts.

The battery is new, only one month old. It is a 700 amp battery.

Anything else I can try?

 

[Dave_eng]

Old..........

I think we should be trying to avoid subjecting your new battery to the high voltages you are reading as they will not be good for its health.

I have been studying the WSM Russell King provided and am a little confused by the Alternator wiring which shows 5 wires at the back of the alternator.

Could you please post photos of the back of your alternator and of your regulator.

Since I started this post, I went to Kubotabooks.com and downloaded the WSM for L175, L210, L225DT and L260 with the idea to review the charging systems thinking your is likely the same.

I would ask you also download the WSM and then look starting at page 29 and then 30.

There is a good description of how the charging light is controlled and I am hoping with your technical skills you can make further observations.

Is it possible that someone replaced the bulb in the charge indicator lamp? The bulb's ohm value is usually important to the proper functioning of the system.

I will be interested in how your borrowed alternator works but am thinking you should borrow both the alternator and regulator to avoid possible damage to your friend's alternator.

Dave M7040

 

[OldGrayOwl]

Thanks, Dave. This explains a lot.
I have a new regulator installed. I thought that this was the problem, based on my troubleshooting. I am going to use my DC clamp-on meter to measure the charging current, and I will let you know.

 

[Dave_eng]

Check for AC current as well as this is what the alternator produces and will leak out if diodes are gone. Multimeters seem to be happy to read AC in a DC circuit with confusing readings.
My gut feeling is some diodes are going in the alternator.

This link may help explain how to test the diodes inside the alternator

http://www.fd-japan.com/catalog/RECTIFIER_TECHNICAL_GUIDANCE.pdf
Dave M7040

 

[OldGrayOwl]

Well,
I checked the voltages at the alternator and they are (at 2K RPM)
E=0 VDC 0.0 ADC
F=17.5 VDC 0.1 ADC
N=9.2 VDC 4.2 ADC
B=17.5 VDC 40.3 ADC

Current at the positive cable:
AC=0.1
DC=40.3

Voltage at the Positive terminal:
17.5

As per Dave's suggestion, I substituted a known good 'charge' lamp from another Kubota (L175), and still no change.

My next step is to replace the wires from the Alternator to the voltage regulator (B, F, N). After unwrapping the tape on the wires, I looked at them. These wires look to be in sad shape and the fast-on contacts are also not in good shape either.

OGO
John

 

[twomany]

If you have a good ohm meter, try to test those wires before and after replacement.
It's hard to get good resistance readings on old connections, but it would be interesting if something significant happened to show up. If these little alternators had some muscle, symptoms of bad connections would show as burnt and melted plastic. ;-)

 

[OldGrayOwl]

Well,
I replace all three of the wires from the alternator to the regulator, the field (F), the neutral (N) and the earth (E) wires, using 16 gauge wire.
I fired the tractor up, and still no change. I unmounted the regulator, and open it up and started the tractor, and it appears that the regulator isn't functioning. If I press down lightly on one of the relays, it starts to move, and the voltage goes down to 13.5, and the current to the battery drops to 10.2 amps. The charge lamp starts to blink in accordance with what the relay contact points are doing. When I release the relay, the current goes back to 40 amps, and the voltage goes back to 16 volts+

Any other ideas for me to try?

Thanks

 

[Dave_eng]

I want to make certain we are at the same page in this saga.

My memory says you tried a regulator from a friend's machine which was working. Did this happen? I think I suggested borrowing both his alternator and regulator for fear of damaging his equipment.

4 days ago you said: "I have a new regulator installed. I thought that this was the problem, based on my troubleshooting."

Am I correct in understanding that the new regulator did not change anything or was this the borrowed regulator?

I really think you need to take the alternator apart and check the internals as shown in the WSM. I think moving the regulator contacts by hand is misleading as you are forcing it to do things at that moment it does not see a need to do.

It is all very frustrating!!!

Dave M7040

 

[OldGrayOwl]

Dave,
You are correct, it is very frustrating.
What I did today was to go back to square one.
I cleaned all of the slip connections with steel wool. I found a 10 gauge wire coming from the fuse block that looked like it was nicked. I had seen it before, but it measured OK, so I let it go. This time, I looked at it closer, and found that it was held together by 3 or 4 strands. I clipped it off, and spliced it back together. I removed my friend's alternator (it was the alternator that I had borrowed, not the regulator), and reinstalled the original one. I started the tractor, and still no change. Still getting 18 volts or so, along with 35 amps to the battery.
I changed out the new regulator for one of the old ones, restarted, and everything fell into place. Voltage 13.5 to a high of 14.2, 3 - 4 amps to the battery. The charge lamp still is dim, but in looking at the schematic, it might be that way, since the lamp is in series with one of the relays in the regulator coils.

I will still continue to check it out while it is still apart, but it looks like the new wiring I did from the alternator to the regulator, plus the cleaning of the contacts is what helped.

Thanks,

OGO