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Charging Issue - Deere F725
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Posted 9/20/2016 08:13 (#5539096)
Subject: Charging Issue - Deere F725

SC Wisconsin
I'm having issues with my battery light coming on and off on a F725 Front Mower I bought as a project. This has a Kawasaki FD592v in it. The battery light will be off after I start it, but will start flickering after 1-2 minutes and will be solid after 30 minutes to an hour. I'm getting 39v AC across the stator leads, and 13.6-14.1v DC across battery at full throttle. I've measured it when the battery light is on solid and not on at all. Similar results.

My limited understanding of the Kawasaki voltage regulator on this is that it compares voltage on the battery charge line to what's coming back from the keyswitch. If there is enough difference, it sends a signal to the battery light. I won't say that's gospel, but what I found on a post in a different forum while searching.

I worked through all the troubleshooting steps in the Deere technical manual (see below) and it passed all them. I've cleaned all connections in the charging circuit, cleaned up the grounds, and installed a new key switch and regulator. The key switch failed the troubleshooting test, even though the tractor ran. The regulator was a "please let this be what fixes it" hail Mary attempt. It didn't. The battery is also new, because the old one was trash when I bought it.

I have a Kawasaki technical manual for this engine, and there is one additional Ohm test in there for the stator itself. The ohms across my stator leads are a bit high. They are 0.6 vs 0.11 to 0.18 per the service manual. So we might have an issue there. Neither lead shows continuity to ground. But I'm hesitant to throw $150 at a new stator and pull the flywheel unless I'm dead sure that's the issue. It seems to be putting out enough AC volts, per the manual, but maybe there's something deeper I'm missing.

I'm stumped! I'd appreciate any thoughts you'd have. Or other troubleshooting steps I could take.



Attachments Diagram_zpslc245e9x.jpg (110KB - 81 downloads)
Attachments Test_zpsxiwmwjjy.jpg (155KB - 66 downloads)
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EJB ( SK )
Posted 9/20/2016 08:42 (#5539147 - in reply to #5539096)
Subject: RE: Charging Issue - Deere F725

My 737 was doing the same thing. Has a Kaw engine. Turned out to be a short in the mower clutch that had more draw than the charge system could handle. When I figured it out the electrical connecter at the clutch had melted.
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Posted 9/20/2016 09:46 (#5539248 - in reply to #5539147)
Subject: RE: Charging Issue - Deere F725

SC Wisconsin
I had that thought so tried it with the clutch unplugged - I still get the battery light. I also tested the clutch and it in spec Ohm's wise with what the manual says. But I wonder if something else might be shorting on mine? Maybe I need to go through all the electrical system tests in the book - I did key and charging circuit, but didn't do the full PTO circuit, and none of the ignition and starting circuits.

I'll also admit I don't understand electrical systems that well. I need the Electronics for Dummies book.

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Posted 9/20/2016 12:50 (#5539493 - in reply to #5539248)
Subject: RE: Charging Issue - Deere F725

Faunsdale, AL
Have you done the testing (of the windings especially) when they are hot and the light is on? Most wiring connections are not going to be heat sensitive and you cleaned all those already, but a winding in the stator could get hot and open or short.

Could also just put a bit of electrical tape over the light since you are getting enough voltage to charge the battery it seems like.
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Posted 9/20/2016 22:03 (#5540358 - in reply to #5539493)
Subject: RE: Charging Issue - Deere F725

SC Wisconsin
Thanks for the idea on testing it hot. I ran with it a bit and figured I'd also check the voltages at different points while it was running and see if I learned anything. The deere manual had me do the checks with engine off.

I figured it would be worth a shot to track down the spot where the voltage in the charging system begins to deviate from battery voltage, since that's what drives the battery light.

Battery voltage was 14.6. Red and yellow wires on the key switch (#5 and 2 in the diagram) were also 14.6. As was the voltage on the red wire into the regulator. So we are good there it seems.

Voltage heading into the circuit board (#6) on the yellow wire coming from the key switch was also 14.6. But that's where the fun ended. Voltage coming out (#7) was 12.3. That's the voltage the regulator is seeing, and why i assume it's throwing the battery light on. So that's something, and I wonder if this a pretty good indication the board is bad? Or maybe I still have a circuit coming off that board that's sucking juice. I need to do some more reading I guess.

I also tried the stator ohms and output test while warm. This was only 5 minutes, not an hour, but I didn't get any change in readings. I'll try it again after the next time I mow.

I'm starting to like your black tape idea!

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