LX178 Electrical System-Charging

CaptMarion · Jun 13, 2010

What charges the battery on an LX178 with Kawasaki Water-cooled VTwin 15 HP when the engine is running?

Is there a generator or alternator somewhere? I looked pretty closely, but I couldn't see anything that jumped out at me. Unfortunately I don't have a shop manual.

While it isn't too much of an issue to just throw a charger on the battery every so often, I'd like to get it working correctly.

Thanks,
-KM
JD LX178
1946 Ford 2N
1950 Ford 8N

rayikeo2 · Jun 13, 2010

The battery can be charged the same as a car battery. Connect charger pos cable first, Neg cable next ( recommended to frame ), plug in charger. Charge at 10 amps or less for 6 to 12 hours. How old is the battery? Is your water cooled motor by Kawasaki or other?

CaptMarion · Jun 13, 2010

I know how to put it on charge-- that's what I've been doing for at least 5 years now. I actually just went and bought a new battery today as it had a several-year-old battery on it that would discharge enough after a couple of times mowing that the PTO clutch wouldn't engage.

It's the 15-HP Kawasaki Water-cooled VTwin...

What I'm asking is, does the lawnmower have something that provides a charge while the motor is running? Like the alternator in a car or on a bigger tractor...?

rayikeo2 · Jun 13, 2010

Under the flywheel there is an electrical coil that charges the battery. There is also a voltage regulater. The charging coil does the same thing as an alternotor.
My 17 HP charges at 15 amp regulated. Yours is probably the same. I found the specs on yours it charges at 15 amp just like mine. LX279 My original battery lasted 10 years before replacement. Never had to charge it. It was a heavy duty 500 CCA battery. Replaced it with a 495 CCA from JD.

CaptMarion · Jun 13, 2010

Okay, that's getting somewhere.

Thanks for the info Rayikeo. Is there a good place online to find info about these? Is the shop manual available online anywhere (like a .pdf or something)?

K7LN- I'll poke my head around the thing and see if I can't find the wires leading to where he's talking about.

Thanks guys

rayikeo2 · Jun 13, 2010

I don't know of any online manuals that are available to view. However if you ask specific questions that you need answered some posters here might have a manual and are able to relay the answers back to you here. Do you think the charging system is not working? Or are you wanting to replace something or do some testing?

CaptMarion · Jun 13, 2010

I'm almost 100% sure that something in the charging system isn't working right. I don't think it's the coil on the flywheel or the stators... I'm prone to think it's a problem in the wiring.

The symptom is that primarily the battery gets discharged through the process of starting the tractor and running it to mow. While the discharge from just the ignition isn't anywhere enough to run the battery down, the discharge from starting it and also from sitting is enough that the battery is noticeably discharged (cranks a lot slower, sometimes the solenoid just clicks and it won't even crank) after starting it and running it a few times.

Since we mow for a good couple of hours at a time, you'd think it would keep the battery charged if the charging system worked correctly. I had to replace the battery (about 7 years old) today because after just starting the tractor and mowing for a few hours, if you shut off the blades, the battery didn't have sufficient amperage to re-engage the mower PTO when you flipped the switch. We also disconnected the headlights as they would discharge the battery very quickly. (I can't remember exactly, but I think they would discharge it even with the lightswitch "OFF", leading me to believe a wiring problem).

There's a diagram of the wiring harness on the Deere website (you can view the LX178 parts manual online), but it isn't 100% clear.

rayikeo2 · Jun 13, 2010

I think the voltage regulator is a solid state plug in module. There is probably an easy way to test the output. I would think that with the mower running if the alternator/charger was working it would be generating enough amperage to run the electric PTO even without a charged battery. Someone can probably answer that for you. I have access to some information but wouldn.t be able to check my source until tomorrow sometime. See if the problem continues with the new battery. Maybe that will take care of it but if the headlights still draw down the battery there is a drain someplace or a week or no charge. There is a chance the battery was the whole problem if it had a dead cell then it would not take a charge even it it was getting the full 15 amps.

CaptMarion · Jun 14, 2010

Okay, we'll see how it goes. Thanks for checking on this stuff for me.

thl · Jul 12, 2010

Ok.

So the question remains. How does one test the voltage regulator to see if it is the problem?

Thanks!

Shimon · Jul 18, 2010

First of all you need to test the battery voltage while the engine is running at speed. It should be 13V -14.5V. If it is then you probably have a bum battery...have it load tested.

If the battery light on the dash is not lit when the engine is running then the stator is putting out AC to the voltage regulator/rectifier. If the battery light is lit then the problem is with the stator and/or permanent magnet. Or the battery light/circuit may be bad. Put 12V to the positive lead of the light to test the bulb and ground circuit.

Check the 15A fuse on the circuit board which provides voltage sensing to the regulator.

You can test stator output by unhooking the 6 pin connector from the voltage regulator and test for AC voltage at pin 4 & 6 (brown/white & brown/yellow). With engine running at speed should see minimum 26VAC.

But it doesn't sound like the stator is bad because you never mention the light.

So, I would guess that you have corrosion somewhere on the wiring (check those grounds!) or you have a battery problem.

Until we know battery voltage while the engine is running at speed...it's hard to say anything. Invest in a decent digital voltmeter if you don't have one. If you don't know how to use one, take the machine to a JD dealer because proper electrical troubleshooting is not easily explained.

thl · Jul 19, 2010

The battery is definitely not charging. I removed the battery and charged it. And then did a load test. Battery tests good.
When running in the mower it will gradually lose charge. This AM the voltage at the battery was 11.65.
I tested the stator and I'm getting about 34 VAC. The ground at the regulator also tests good.
Is there any type of impedence check that can be done on the pins of the regulator?

Thanks,

Terry

Shimon · Jul 19, 2010

thl said:
The battery is definitely not charging. I removed the battery and charged it. And then did a load test. Battery tests good.
When running in the mower it will gradually lose charge. This AM the voltage at the battery was 11.65.
I tested the stator and I'm getting about 34 VAC. The ground at the regulator also tests good.
Is there any type of impedence check that can be done on the pins of the regulator?

You can't test the regulator directly because it's a solid state device. At least I don't know how without having the proper parameters and data for the device...plus you would need an o-scope.

If you have good AC voltage at the stator (sounds like you do with 34 VAC) and you don't have good output DC voltage from the voltage regulator/rectifier then you have a bad voltage regulator.

Before condemning it, I would check the voltage at pin 1 and 3 (red and black wires) while the connector is still connected to the voltage regulator and the engine running at speed to be sure the problem isn't in the wiring closer to the battery. I wouldn't use any other ground except the one at the connector while testing. Also, check that you have actual battery voltage at pin 2 (yellow/black) which is the voltage sensing wire feeding the regulator.

Assuming all the wiring is ok (tests above come out ok), it looks to me like you need a new regulator.

Shimon · Jul 19, 2010

thl said:
The battery is definitely not charging. I removed the battery and charged it. And then did a load test. Battery tests good.
When running in the mower it will gradually lose charge. This AM the voltage at the battery was 11.65.
I tested the stator and I'm getting about 34 VAC. The ground at the regulator also tests good.
Is there any type of impedence check that can be done on the pins of the regulator?

I notice that you are not the original poster. Are you having the same problem that CaptMarion is having?

thl · Jul 22, 2010

Shimon said:
I notice that you are not the original poster. Are you having the same problem that CaptMarion is having?

After reading the veneralbe Captian's first post I would venture to say YES. For the last year or two I've been doing much the same. I keep a trickle charger next to the mower's parking space and simply charge it before using. I've been avoiding the cost of the regulator until I was more convinced that it is the problem.

thl · Jul 29, 2010

Shimon said:
You can't test the regulator directly because it's a solid state device. At least I don't know how without having the proper parameters and data for the device...plus you would need an o-scope.

If you have good AC voltage at the stator (sounds like you do with 34 VAC) and you don't have good output DC voltage from the voltage regulator/rectifier then you have a bad voltage regulator.

Before condemning it, I would check the voltage at pin 1 and 3 (red and black wires) while the connector is still connected to the voltage regulator and the engine running at speed to be sure the problem isn't in the wiring closer to the battery. I wouldn't use any other ground except the one at the connector while testing. Also, check that you have actual battery voltage at pin 2 (yellow/black) which is the voltage sensing wire feeding the regulator.

Assuming all the wiring is ok (tests above come out ok), it looks to me like you need a new regulator.

Shimon,

I did the last two tests. Tests came out ok.

I ordered a new one from Pat's Small Engine in MN. Received it today, just installed it and behold, the tractor is now charging.

Thanks for all your help,

Terry

OliverArk · Aug 30, 2010

I had the same symptom with my LX178, but the battery light would come on while mowing, if I moved the wires around near the regualtor the light would go out. Inspecting the wires at the regulator I found one of the terminals in the connector burnt. I removed the terminal from the connector and soldered a new one on, cleaned the terminal on the regulator and applied die-electric grease and works like a champ now. I think maybe age and vibration caused this.

Snipe · Apr 30, 2011

I hope that is what just happened to mine this evening. NO POWER any where though. Hadn't had time to look at anything yet. Fuses looked good.Running good light was flickering, touched harness and then nothing. Lost all power. Find more out Mon. a.m.

Shimon · Apr 30, 2011

Snipe said:
I hope that is what just happened to mine this evening. NO POWER any where though. Hadn't had time to look at anything yet. Fuses looked good.Running good light was flickering, touched harness and then nothing. Lost all power. Find more out Mon. a.m.

If your battery voltage is good then it's a fusible link or a fuse or loose/bad connection.

lexluther1971 · May 14, 2014

Shimon said:
First of all you need to test the battery voltage while the engine is running at speed. It should be 13V -14.5V. If it is then you probably have a bum battery...have it load tested.

If the battery light on the dash is not lit when the engine is running then the stator is putting out AC to the voltage regulator/rectifier. If the battery light is lit then the problem is with the stator and/or permanent magnet. Or the battery light/circuit may be bad. Put 12V to the positive lead of the light to test the bulb and ground circuit.

Check the 15A fuse on the circuit board which provides voltage sensing to the regulator.

You can test stator output by unhooking the 6 pin connector from the voltage regulator and test for AC voltage at pin 4 & 6 (brown/white & brown/yellow). With engine running at speed should see minimum 26VAC.

But it doesn't sound like the stator is bad because you never mention the light.

So, I would guess that you have corrosion somewhere on the wiring (check those grounds!) or you have a battery problem.

Until we know battery voltage while the engine is running at speed...it's hard to say anything. Invest in a decent digital voltmeter if you don't have one. If you don't know how to use one, take the machine to a JD dealer because proper electrical troubleshooting is not easily explained.

I have the same charging issue LX178, however my light IS on and the stater is fine!! It tests 31.5 volts ac.

Your saying if its on the stater is bad, but this doesn;t seem the case. If I unplug the regulator the light doesn't come on, and while plugged up doesn't even get warm. Where is this 15 amp fuse?