Craftsman tractor not charging the battery

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  #1  
Old 04-27-14, 12:47 PM
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Craftsman tractor not charging the battery

I have a Craftsman tractor model 917-271020. It runs fine, but the ammeter indicates a slight negative current while the tractor is running. Eventually when the battery drains too low it will no longer start until I recharge the battery with a trickle charger.

The engine is a Kohler 15.5 HP model CV15S. I've located the service manual here http://www.kohler-engine-parts.opeen...5_DATE4_11.pdf and have walked through the various trouble-shooting steps to try to diagnose the charging system. The engine has the 3 Amp unregulated charging system with the optional stator brake.

1. I've had the battery tested at my local auto parts store. It checks out fine.

2. With the engine running and the black battery charging lead from the stator disconnected and measuring the voltage from the lead to ground I on got a 2-3 volts. So it seems I'm not getting enough voltage out to charge the battery.

3. With the engine off and the black battery charging lead from the stator disconnected I ran a diode check across the diode that's in-line with the black lead. It measured a forward voltage of 0.56 V and looked fine. So it seems like the issue was not the diode, but the stator itself.

4. With the engine running and the yellow AC lighting lead from the stator disconnected and measuring the AC voltage from the lead to ground I got pretty much near zero. So it seems like the stator wasn't producing any AC, thus nothing for the diode to rectify and charge the battery.

I bought a new stator and installed it. However I'm seeing very similar symptoms. No AC off the yellow lead and no DC off the black lead. I measured the resistance from the yellow lead to ground and got 0.15 ohms, exactly as the manual specified. So the stator wiring appears to be good.

Any suggestions as to what else I should try?
 
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Old 04-27-14, 09:35 PM
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Did you throw a flywheel magnet? Was old stator damaged when you removed it? Even if magnets are intact, you may need a new flywheel...
 
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Old 04-27-14, 11:13 PM
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It does sound like your flywheel magnets may be an issue.
 
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Old 04-28-14, 04:09 AM
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I took a quick look at the flywheel magnets and they all seemed ok (all still there, nothing missing). The old stator looked fine, no evidence of any physical damage. It just seems very odd. If the magnets are moving past the stator they have to produce power. Other than a missing or broken magnet is there any other type of problem the magnets could have?

I also considered the possibility that the stator wasn't grounded correctly, but since I can measure the proper resistance from the yellow lead to a grounded bolt on the chassis I figured the ground must be ok.
 
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Old 04-28-14, 09:18 AM
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Check for AC voltage between the stator and the diode with the engine running and the positive lead on the wire and the negative lead grounded.
 
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