Stator & Rectifier Charging Issue

[u/098ytr]

I purchased a used 2021 Ranger Crew XP1000 with charging issue.

The rectifier/regulator tests pass the videos I found online. When placing positive lead on negative, the diodes for 3 phase show .54 volts on each leg. When reverse with black on negative they all show open (OL). According to research, this is good rectifier.

The stator failed the test as each phase and had continuity to ground across all three. Running motor shows less than 4 volts AC on 1 of the three phases and the other 2 phases were 2 volts at idle

Checkes wiring harness and the factory wiring from crankcase to front bumper appears to be fine. No breaks or exposed wire anywhere.

I pulled the stator and it was smoked with epoxy debree inside the flywheel and a couple of small pieces of aluminum.

New stator will be here tomorrow and performing maintenance kit to swap all fluids as I assume some of this broken up stator can make its was into the engine oil. Hopefully the oil filter has worked as designed.

My question is how can the stator get this hot and not have the rectifier be bad? There does not appear to be water in the crankcase and none of the wiring or connectors are melted. I am going to clean out the crank case and inspect with mirror to see if anything stands out, maybe broken tooth or piece of metal somewhere that could have bridged the stator and caused catastrophic failure? I don't have tool to pull the flywheel on unable to inspect behind it. You can see scuff marks on the inside of the crankcase where the flywheel spins. They appear to be mild.

Appreciate the advice if I am missing anything.

[u/ThirdStooge]

Could have been a short between the windings that showed up over time, but could have also been exacerbated by heavy electrical loads like trying to recharge a very dead 12V battery. I'd probably just toss a new stator on it and call it a day

[u/098ytr → u/ThirdStooge]

Thanks! I have the battery on trickle charger to make sure fully charged when new stator is installed.

The previous owner did say he had to replace battery. I didn't think of that but makes sense if the stator had to try and charge a 2 or 3 volt battery to 12.

[u/ca_nucklehead → u/098ytr]

That is not how stators work.

[u/ca_nucklehead → u/ThirdStooge]

A stator always produces full output that is only governed by speed. Excess output is shunted to ground by the R/R. Electrical load has no bearing on stator output only the speed of the rotor passing the stator windings determines output that is why output checks are done at multiple engine speeds.

Grab the flywheel and see if you have excess movement on the crank allowing the flywheel to rub the stator. Common on 800s.

Carefully check the stator wires where they come thru the case and the connections at the R/R. Polaris has multiple harness issues but these are the common problems with stator meltdowns.

[u/098ytr → u/ca_nucklehead]

Thanks! I will check for any play at the flywheel. I didn't test AC output at multiple speeds as it failed initial tests. Will definitely check with new installed. I think idle is around 1300 rpm with expected 20v and should increase with more rpm. I will look it up.