I have an 1998 Sportsman 500. It seems that im replacing battery about every 3 months or either having to charge the ones that are in it. Does anyone know what the problem could be? Ive heard the rectifier could be bad, the modulator, so on. Is there any way i could find out what the issue is or can you guys offer any help? Thanks alot!

 

Get a voltmeter on the battery terminals.

With the ATV shut off should read 12v at the battery,and with motor running at 4000 rpm it should read 13V - 14.6V.

If your ok and still have troubles I would change the Voltage Rectifier/Regulator.

 

try unhooking the recifier and checking the connection for corrsion. as mentioned above w/ a tester you should be able to check voltage.

 

Regulator in front of radiator is bad. Usually the problem, do some testing with a meter to make sure its not charging first.