Ztrek Charging system

[Plat Doc]

I have a F687 Ztrek with a 23 hp kohler. It will not charge the battery. I have 36volts AC coming out of the stator at WOT. I have 12v from the battery to the center spade on the rectifier. I put on a new rectifier and no change. Where do I go from here? The battery is 1 yr old.

 

[Steve_in_Ga]

Have you checked the stator? If you are getting that much voltage to the rectifier it seems that one side of the stator is open, probably a broken wire or bad connection in the plug.
Steve

 

[Sidekick]

There should be more than 12 volts coming from the rectifier. Check it by putting one lead on the dc output spade and the other to ground, not the battery. Check your stator with an ohmmeter. There should be next to no resistance measured. Then check each stator lead against ground. There should be no continuity. I just went through this with my mower and if you're only charging 12 volts it's not working properly.

 

[Plant Doc]

Sidekick: Thanks for the response. The 12v at the rectifier I was
referring to was with the rectifier plugged into the three spade plug.
I was checking to see if the wire feeding the Battery + to the center
rectifier spade had continuity. I also ASSUMED that because there
was 36v AC between the two stator wires at WOT the stator was OK.
But I will check the stator with an ohmmeter as you described. I
inherited this mower with a broken crankshaft. It was broken
behind the flywheel and maybe when it broke the flywheel damaged
the stator or the wires leading to the rectifier. I hate to have to pull
the engine back out of the mower, but it looks like it is the only
way. Thanks again.

 

[Sidekick]

36 volts sounds ok to me. Just for grins I went out and checked the output of my Kohler 20 and it shows 36-38 vac at the stator and 15.25 dc output at full throttle. The old rectifier that I replaced last week was only charging 11-12. You can also check the rectifier with an ohmmeter. There should be some continuity between the dc and ac tabs no matter what lead polarity you use. If there is a short between them then you've found your problem. I can't remember exactly what it's supposed to read but there should be something checking both ways. Pull the plug off before you check to remove the stator from the circuit. But I bet the stator is fine. Is it possible the battery might not be up to snuff? Sometimes last years battery doesn't survive the winter very well. I've had that happen.

 

[Plant Doc]

Sidekick: One more quick question, do you have a ground wire
attached to the rectifier on your kohler? I do Not! If I put my test
light between the rectifier and ground with WOT the system
charges. But with engine stopped if I put my voltmeter between the
rectifier case and ground I get current flow. Only a few volts but
maybe enough to drain battery when not in use? Any suggestions?
Thanks again.

 

[Sidekick]

Yes, I have a ground wire from one of the rectifier mounting screws to another nearby screw.

I don't quite understand your question. You're measuring voltage at the rectifier with the engine off? There should be none.

I'd try putting a ground wire on the rectifier and see if that helps. It's easy enough to try.

 

[Johndeerebones]

As a general rule you have to have twice in VAC what you want DC. The rectifier is a switch if you will that is only on 1/2 the time. Yes you need the aforementioned ground due to a plastic mounting otherwise. Do the continuity checks he gave earlier to check the stator. Unhook it from the rectifier first though. The leads should have no continuity to each other or each to ground. There should be very little resistance to flow between the two. If it fails any of these it is bad. Check into it though if you do replace it, OE is 3 amps, the new ones are 15 amps and require different wiring. It all comes as a kit with directions.

 

[Plant Doc]

Thanks to everyone that responded. The system is now charging. The problem was a ground wire. Once I grounded the rectifier the system charged at 14.2 volts at the battery. I have a wiring diagram from Kohler and it shows no ground to the rectifier. I even checked again to make sure I didn't miss anything. Just proves this forum is better than kohler. Thanks again.