Arkie wrote:Yes, appears to be something wrong with the stator, but too much voltage does not sound logical. Usually it's too low or none at all...
I don't want to use the resistors because, as a technical guy, I want to know what is bugging that circuit. It's become a personal thing now.
bgsengine wrote:rms59 wrote:The Kohler diagram.
https://i.imgur.com/08Cj187.pngI understand the confusion on the wire colors but the stator has only two wires. A black one and a green one. The black one measures 14V (lighting) and the green one 28V (charging). .
So which is it? n an earlier post, you seemed to be saying you were getting 40 VAC at the green wire at WOT... Only measurement that *matters* is the one at 3600 RPM (WOT) - it is pointless to check output voltage at the stator anywhere else than normal operating RPM, especially when diagnosing a charge output issue .. So, do you get 28V at WOT or 40V ? If it is 28VAC at 3600 RPMs then your half wave rectified voltage (via Diode) should only ever be 14 volts DC (up to 14.8 volts) .. 40VAC would be giving nominally 20 VDC at full throttle - in any case.. anything over 15 volts is going to FRY your battery if it is allowed to continue.. so.. If your measurements are correct, something ain't right - So you either got engine (flywheel magnets) spinning too fast, or you got extra voltage leaking from other stator coils (as was suggested earlier), or your test meter is off somehow. When you had flywheel off did you check the magnets to see if any , by some chance, might have been loose? (spacing between magnets) They've been known to separate and "cluster" together, so it's within realm of possibility (though Ive no idea how it might happen) an odd cluster of magnetism could be multiplying voltage.. though the ones I found with magnets like that were diagnosed due to LOW output voltage, I suppose a theory could be put out that same thing could cause an over-voltage..
However - Any meter readings are and will always be suspect until you are able to actually check engine RPMs (simple maintenance tachs are accurate enough for 4-stroke single cylinder work, and Ive seen them for under $20 these days)
Both. The 28VAC was initially measured with engine at idle and I never had a reason to check it at WOT because it was already 6 amps at idle and solder melting 9 amps at mid throttle range. During following tests I did go to WOT and the voltage across the battery was measured at 40VAC. Since you mentioned accuracy of the meter I put my Simpson Analog 260 and my Craftsman digital RMS meter across the output of a 24VAC wall transformer and then across the 120VAC line and got exact readings. Then I started checking some 1% resistor values just for kicks and got same results. I'm glad you brought that up since I haven't checked calibration in a long time so now I'm happy that I did read that 40V correctly.
Borrowed a meter and at WOT I read 3430 RPM and 1510 at idle. Don't know if that is good or bad but the blades turn fast enough.
The flywheel magnets (6 of them) are clean and tightly bonded. I took a screwdriver and held it about 3/4 inches away from each one and they pulled in hard. The stator has no scrape marks, nicks, or discoloration.
KE4AVB wrote:rms59,
The lighting wire is optional per the SM and yes I had one unit I repair last year where the yellow lead was connected to the black lead at the diode anode then another black lead attached to the cathode which continued on to the battery. Green lead is definitely on the stator brake circuit.
Humor me here disconnect the green lead, move the diode to the black lead observing the correct polarity, and connect this new setup to the battery. Then test for both the correct voltages and amp draw at full throttle. At idle there may not be enough voltage to produce a charging current but this to be expected with nearly fully charged battery.
With the green (and yellow that goes to the operator relay) not being used, I connected the diode to the black wire. At idle there was 12.0 volts across the battery terminal and at WOT it got to 12.7
Arkie wrote:bgsengine wrote:rms59 wrote:The Kohler diagram.
https://i.imgur.com/08Cj187.pngI understand the confusion on the wire colors but the stator has only two wires. A black one and a green one. The black one measures 14V (lighting) and the green one 28V (charging). .
So which is it? n an earlier post, you seemed to be saying you were getting 40 VAC at the green wire at WOT...
Only measurement that *matters* is the one at 3600 RPM (WOT) - it is pointless to check output voltage at the stator anywhere else than normal operating RPM, especially when diagnosing a charge output issue .. So, do you get 28V at WOT or 40V ? If it is 28VAC at 3600 RPMs then your half wave rectified voltage (via Diode) should only ever be 14 volts DC (up to 14.8 volts) .. 40VAC would be giving nominally 20 VDC at full throttle - in any case.. anything over 15 volts is going to FRY your battery if it is allowed to continue.. so.. If your measurements are correct, something ain't right - So you either got engine (flywheel magnets) spinning too fast, or you got extra voltage leaking from other stator coils (as was suggested earlier), or your test meter is off somehow. When you had flywheel off did you check the magnets to see if any , by some chance, might have been loose? (spacing between magnets) They've been known to separate and "cluster" together, so it's within realm of possibility (though Ive no idea how it might happen) an odd cluster of magnetism could be multiplying voltage.. though the ones I found with magnets like that were diagnosed due to LOW output voltage, I suppose a theory could be put out that same thing could cause an over-voltage..
However - Any meter readings are and will always
be suspect until you are able to actually check engine RPMs (simple maintenance tachs are accurate enough for 4-stroke single cylinder work, and Ive seen them for under $20 these days)
Per the wiring diagram, 28vAC at 3600 rpms' It also indicates this is open circuit voltage,
charging system disconnected from the battery. This is your specs for checking the charging system. You can get a tach from flea bay for less than $15.
If WOT is more than 3600 expect the AC stator voltage to be higher. You cannot assume that WOT is not more than 3600 in your case.
With 28vAC and half wave rectification the output voltage should be
for that stator system around 14.8volts or not over 3 amps to charge a 12v bat. (that is the max specs for that stator)
Yep. Initially No Load is how I measured the 28 and 14 to gnd.
When I first got to look at this Craftsman tractor after the initial diode meltdown, my brother already cleaned up the wiring so I can't verify how it was connected. But on my Husqvarna I can clearly see two wires coming from the stator with one going to a small diode, the ammeter, a fuse, and then to the battery while the other wire goes directly to the lights. There is no third wire. Since both the Craftsman and Husqvarna schematics I linked to show the charging and lighting circuits to be almost identical in nature I'm 99% sure the 2-lead Craftsman is wired the same way.
My brother is ordering a new stator (around $30) on a roll of the dice that this will solve the problem. This whole thing to me is like bizzaro world physics where a broken egg falls off the counter and lands on a concrete floor becoming a whole egg again. It just doesn't make sense.
I promise to get back with the results in a few days. Thanks to all for the insightful help and I have to tell you this is the only help forum that I didn't have to wait days for responses. You guys are great and I will get back.