Basket case of a Sportsman 400

Ive got an 01 sportman 400. Its been acting a fool with the starting and charging system on and off recently.

I replaced the starter, starter solenoid, and battery recently. Everything was all and well until the battery died. I then realized it wasnt getting charged.

I charged the battery and it was back to being able to start just fine. I get a few days of riding it then its back to the pull start until I can get it charged.

Just the other day it stopped starting even with a charged battery. I suspect the cheap solenoid I put on it went out but I have tried to jump it yet.

My question is, is it the stator that would cause it not to charge? or is there something else. I do have a volt meter and can test things, but im honestly very new with it. (What im trying to say is I dont know what to set it on to get specific readings).

Thanks for the help in advance.