have experienced low votage on and off for awhile, two new batterys and now low voltage all the time.generally 8 volts at the battery with multiple spikes to 12 and above. the spikes happen mostly when the fan kicks on. have traced the wire harness for possible shorts or open with no results. spikes are intermitten at best. if you unplug the regulator, spikes stop. atv runs fine but accessories are low voltage, ie fan, lights etc. stator, ring and regulator expensive if not the problem, any help??????? oh after charging the battery, starter works till drawn down again. pull rope start ok even if battery is dead.

 

Sounds to me like Ya got what is called a Dead Short somewhere, I would look around the fan area sounds like when it kicks on it jars the shorted wire off its contact and when the fan turns off the wire settles back and shorts out again. The low volt is the machine trying to keep a charge on the battery, the up spike is the battery recharging itself when the shorted wire losses contact with metal.

Put a volt meter on your frame when the machine is running and see if any current is running through it, sometimes when you have a dead short issue and the machine is running it may show a minor current running through the frame.

 

have been buying aftermarket batterys from(polaris of gainesville) and tryed somthing new. i unhooked the battery from the machine and did a charge. cleaned the posts,(saw no corrosion) for maybe an hr with a 2 amp.reconnected everything and low and behold showing a charge. ran machine for 2 hrs and no problems, question is is the voltage reg controlled by the battery? and not the machine?in automotive apps, even if you have a bad battery, you still have charge.after 2 hr of running machine charged and restarted. dont know if i fixed the problem or just bypassed it. automotive knowledge tells me if you have a weak battery, once your running all is well unless you shut it off. machine would run, but lights and fan would run slow. i checked for shorts to the frame, and burned myself a bunch, lol but this threw me for a loop, any suggestions?

 

If this was a car the first thought I would have is the alternator is going out. Not that informed about the MC engine, but it sounds like to me if there is no short then whatever "Voltage Regulator" that keeps the battery charged is bad and it's grinding down the batteries.