911 problem on wheel horse charging system

[daveshoe]

My 20 HP Onan powered lawn tractor is discharging the battery just to run the spark plugs. This problem is severe enough that it will show output at the amp gauge ot 10 amps right away and 8 amps after running an hour. At two hours ,it will be so bad that the spark plugs will not fire. I tried a second battery from another machine,and she started right up,only to repeat the problem.

I think the flywheel magnets are what generates the power for this machine. I also assume that some type of voltage regulator is used to regulate the charging function. I could understand the older tractors that had a starter/generator, but am clueless as to what generates power to fire the spark and charge the batteries. The machine in question is a horizontal shaft Wheel Horse lawn tractor.

 

[KBennett]

From what I have experienced there is a generator coil under the flywheel. When the flywheel spins it has magnets that cause a magnetic field to be generated through the coil creating electricity. This electricity is AC. The AC voltage is fed to a metal box or module that has diodes in it to convert it to DC and then regulates the voltage for the battery.

1. Check all your wiring and fuses. This is most likely your problem.

2. Check to see if there is AC coming from the generator coil if you have a way to test.

3. Voltage to the battery should be 13+ volts when running if not you may need to replace the regulator module.

 

[FATCAT]

My 20 HP Onan powered lawn tractor is discharging the battery just to run the spark plugs. This problem is severe enough that it will show output at the amp gauge ot 10 amps right away and 8 amps after running an hour. At two hours ,it will be so bad that the spark plugs will not fire. I tried a second battery from another machine,and she started right up,only to repeat the problem.

I think the flywheel magnets are what generates the power for this machine. I also assume that some type of voltage regulator is used to regulate the charging function. I could understand the older tractors that had a starter/generator, but am clueless as to what generates power to fire the spark and charge the batteries. The machine in question is a horizontal shaft Wheel Horse lawn tractor.

Man ... that is the EXACT problem I had with my old WheelHorse tractor before I gave it to my sister-in-law. I had a 920 model (or something like that) with a 20 hp Onan.



The whole problem was the wireing harness ... it was all chafed and discharged the battery right out into the frame. As you sit on the tractor, open the hood and right behind the dash along the right side of the tractor under the battery tray is the harnes and cliped on the right frame are a couple of inline fueses. These are the wires that need replacing. Also remove the floor and under steeringwheel plates and you can get in there and pull out the wiring harness.

 

[daveshoe]

Thanks!

The fuses are spade type and insert from the top. Old grass chaff and moisture and battery gunk found a way in and really had the 30 amp fuse pretty corroded. I put in a new fuse and used di-electric grease and she charges fine now. This is a really good machine and has only had minor problems like safety switches , a starter that responded to a clean-up and re-grease the Bendix. 600 hours on it and I am pleased.

BTW Onan is a subsidary of Cummins [I think]

Another helping hand from the fine members of TDR. Thanks Fatcat and

KBennett!