John Deere 445 Charging problems

[G Archer]

Hi everyone , My 445 will not charge the battery.Charging light will come on when pto is engaged or when the headlights are on.Manual says you must have at least 26 AC volts on each leg of the stator.I had 17 Ac volts,so I replaced the stator with a new one,now I have 20 volts AC,still not enough.The flywheel looked fine with all magnets intact.The manual says check the stator with the reg/rec unpluged.What am I missing here? Kawasaki 22 HP OHV EFI Liquid Cooled Thanks for the help



Glenn

[KE4AVB]

Appears to have FD620D engine.

Are you measuring the voltage from each leg of the stator to ground or is it across both wires. The check is done across both wires. Also are you doing this at 3000 RPM?

You need to unplug it to check the stator coil resistance which should be between .11 and .18 ohms with no resistance to ground. If stator resistances is within specs and the output voltage is still too low then the flywheel and magnets (ie Rotor) needs replacing as they may have weaken.

[G Archer]

Thanks for the reply.The JD manual says check each leg of the stator with one lead with the other to ground.MIN 26 AC volts.I have 17.5.Checking then together I get 37.5.I doesnt say what the combined voltage should be.Hope this helps.Are the magnets prone to getting weak? Thanks,Glenn

[KE4AVB]

Must be a different manual than the Kawasaki FD620D service manual I have here. I would say your stator is fine from the 37.5 VAC reading and that you have a voltage regulator problem. Need to do the resistance checks on it to verify.

[KE4AVB]

Are the magnets prone to getting weak? Thanks,Glenn

Forgot the answer this part of your reply.

Personally I haven't seen any; it just mention the Kawasaki service manual. The only time I seen stator failure caused by a magnet problem was when a screw/bolt was drop into the area by a customer when he was replacing a breather gasket on a Kohler horizontal twin. Both the magnets and stator were destroyed as a result.

[Skywatcher]

Hi All

You need to unplug it to check the stator coil resistance which should be between .11 and .18 ohms with no resistance to ground.

KE, I think you may have used a wrong term here. Resistance to ground should be infinity or no connection to ground. The AC circuit of the charging system must be completely isolated from machine frame or ground. The voltage regulator/rectifier must be grounded though. All the best,

Sky

[KE4AVB]

Yes probably I could have said it better but that I get for doing electronics for 30+ yrs. To me there is always a little resistance to ground but I did mean no measurable dc resistance (infinity; open circuit) connection to ground. It some my residual thinking from the analog meter days especially the old Simpson 260 where no needle movement indicated no connection to ground.

The AC voltage measured to ground is the capacitance or inductance coupled voltage that is present when the stator is not loaded at all. A similar thing but much more pronounced happens on my RF antennas where I applied a voltage on the gamma or T match. Although the antenna itself is earth grounded and the gamma match center conductor has no measurable dc resistance (infinity) to ground I can produce considerable RF ac voltage on the elements (arms) that radiate from the ground point. It one of the reasons that I got have them out reach especially when applying 2 KW to the gamma matches. RF electrical burns can be very nasty. The gamma match uses capacitance coupling to an inductive array. Even my coaxial and parallel cables that has infinity dc resistance between the two conductors still produces a 50 ohm or other design RF ac resistance though capacitance coupling.

[G Archer]

Thanks for all the replies.Replaced the regulator and fixed the problem.I was checking the stator wrong.All was not lost as I found my oil leak on the crankshaft seal.Thanks again, Glenn