Engine John Deere 320, possible stator is bad?

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spepple1989

Member
I bought a 1992 John deere 320, ignition switch was out, so I replaced that, got it running, have continuous battery light on, reading 12.63 volts on battery, same while running, I disconnected harness from regulator, battery light goes out, tested voltage through harness where it connects to regulator, it reads the same. can anyone give me any input on this?
 
Just to clarify - you checked the voltage coming out of the stator but before the regulator? Or you tested voltage out of the regulator? If the former, and you're only seeing about 12 volts, then yes, something in the stator is going bad and it's not generating enough voltage to keep the battery charged. On average you need to see at minimum 13.5 volts to charge a 12 volt battery. If you've got accessories - such as headlights - you should be seeing 14.5+ volts because otherwise the battery wouldn't be getting charged or the headlights wouldn't be running at full capacity.

But keep in mind - this is after the voltage has passed through the regulator. As its name suggests, it's supposed to regulate the amount of voltage leaving the stator to prevent over charging the battery and frying wires, therefore I'd expect to see at least, if not more than, 15 volts leaving the stator before entering the regulator.

To make it a little easier: pre-regulator you should see at or above 15 volts -- post-regulator you should see no less than 13.5 volts.

I should also point out that I'm not a lawnmower expert, but I am an auto mechanic and the same principles operate both systems. The difference is going to be in the actual numbers and whether or not the stator on your mower is supposed to generate that much voltage - it could be more or less. But even so, you should see more than 12.6 volts to charge the battery.
 
ok, so I tore down top of motor(radiator) and that plastic shroud off, figured out which wires are the stator wires, and which harness they go directly into, I probed the backside of the wires going into the harness, if I put it in dummy mode and just turn motor over without starting its around 5v(ac) and if I let it run on almost full throttle I'm getting 2.5 to 2.8v(ac) on my meter.
 
Please post the engine model numbers, that way we will know which charging system you are dealing with.
 
spepple1989 said:
ok, so I tore down top of motor(radiator) and that plastic shroud off, figured out which wires are the stator wires, and which harness they go directly into, I probed the backside of the wires going into the harness, if I put it in dummy mode and just turn motor over without starting its around 5v(ac) and if I let it run on almost full throttle I'm getting 2.5 to 2.8v(ac) on my meter.
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Is your meter auto-ranging or is this a typo? Because it makes no sense for you to be getting 5vac turning the engine over by hand, and only 2.5-2.8vac at full throttle. Did you mean 0.5vac when turning it by hand? It's a pretty basic principle - the faster you move the armature through a coil of wires, the greater the voltage generated.

If, however, your meter is auto-ranging (or you didn't have it set correctly because I'm not sure what you mean by "dummy mode") then it's probably 5vac turning by hand and 25-28vac at full throttle.

You need to clarify which readings you're getting. According to the manual Rivets linked you to, you should be seeing 26vac unregulated output (before the regulator) at 3,000 RPM (which I'm guessing is full throttle).
 
ok, so here's an update, I bought a used stator cheap to do some testing, while I was at it, I cleaned the inside of the flywheel, was dirty and gummed up with dirt and dust and grass. out of both stators I'm averaging 8.5 volts. my ohm reading on both is .4 to .5, which by the book is too high from what I understand.
 
spepple1989 said:
ok, so here's an update, I bought a used stator cheap to do some testing, while I was at it, I cleaned the inside of the flywheel, was dirty and gummed up with dirt and dust and grass. out of both stators I'm averaging 8.5 volts. my ohm reading on both is .4 to .5, which by the book is too high from what I understand.
Click to expand...

When you measured stator resistance, was it unplugged from the harness? A must for accurate continuity (resistance) checks is the circuit has to be dead. Even a static (residual) voltage can throw off the resistance. You can discharge a residual voltage by connecting a test lamp between the stator pins in the connector. Also, was it still warm from the engine operation? Heat adds resistance, so that can effect your readings also.

When you had the flywheel/stator assembly apart, did you check the integrity of the reluctor wheel? It should be mounted under the flywheel and inside the stator - it's what would be rotating within the stator to generate the voltage. It should look like a gear with small, stubby teeth. Broken or missing teeth, or if there's a crack in the wheel (from the manual, it's not clear to me if the reluctor wheel is machined into the flywheel or if it's press fit) can cause low and/or inaccurate voltage generation. The stator magnets need to have a constant rotation of the reluctor wheel teeth to generate steady, strong voltage. Even the smallest of cracks or chipped or missing teeth can bring the whole system down.

You may be getting frustrated at this point, but keep updating us (pictures help too, if possible) and we'll keep guiding you through it. And if necessary, walk away for a while - sometimes even a 10 minute break can do wonders for keeping your head level. :thumbsup:
 
ok, I won't have any time til this evening to pull it apart, but yes the stator was disconnected when I checked resistance, and the motor was cold, had not been run at all. however I didn't try putting a incandescent light bulb on it to try. and I'm not sure if I know what you're talking about with the reluctor wheel and gear, but I will pull the flywheel and inspect and try to find this.
 
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