John Deere 116 fails to charge battery

[Mtn.Mike]

I'm working on the above mower with a B&S 16 HP twin model #402707013101 and I can't get the battery to charge. The battery reads 12.7 volts while running but it will decrease as the mower runs.
I've checked all the wiring, made sure that the cables are free of rust but I can't figure out how the battery charges.
I have one green wire coming out from under the flywheel and it shows 12.7 volts. There is another wire coming out from under the flywheel and it goes to the coil which I assume is the ground.
Can someone give me some help as to what to look for?
The battery is new and fully charged and tested and I can find no fuses to check. This is an old mower that a friend got for free.

Thanks, Mike

 

[Rivets]

The stator which charges the battery is located under the flywheel. Please clarify something, you state that you have one green wire come out of the engine. Could this be a green connector with a black wire? Where does this wire go to?

 

[Mtn.Mike]

The green wire connects with a spade connector to a red wire that goes into the wiring harness.

Mike

 

[Rivets]

Hate to say it, but I think someone has played with the wiring. With today's engines the only time two wires come from under the flywheel, they should go to the same connector. I don't think I will be able to help you unless you can take the flywheel off and post some pictures. I just won't know what you are seeing. A green wire under the flywheel is not normal and unless I see what your seeing, I don't want to tell you something wrong that could cost you big bucks. Sorry.

 

[Mtn.Mike]

Thanks Rivets: I will take the flywheel off and try to get some pictures.

Mike

 

[EngineMan]

Anyone have a wiring diagram on this, I can't find one anywhere...!

 

[Mtn.Mike]

After removing the flywheel I found that there was a single black wire coming out of the stator. For some reason the black wire was then shrink wrapped to the green wire. Once it connects to the red wire it then goes to a "module".
There is another wire coming from the same space in the module that the red goes into and it appears to have been cut off. I have no idea where that wire was supposed to go?
I appreciate all the help so far and will continue to try to get this mower charging.

Mike

 

[Grassbandit]

when the engine is running the battery is supposed to read something like 14 volts . So I'd say the field coil has stopped functioning and needs to be replaced or you can bypass it by getting a battery tender module and save yourself the hassle.

 

[rmancini]

Found this diagram. Don't know if it helps but here it is.
Rich

 

[Rivets]

Did some checking and found that you have a Tri-Circuit Alternator Charging system. I have asked another member to post pictures and a description on how to test the various parts of the system. If he is unable to do so, I will figure out another way to get this info to you. Hang in there and we'll get this solved. Please don't replace any parts until you can test them.