Was out setting some game cameras out yesterday and managed to get mired in some Spring mud. The winch was not pulling as hard as I remember in the past. I think my battery is on the verge of needing to be replaced, would the battery condition have anything to do with how well the winch works. The machine was running the whole time and never died it just seemed to get max'd out and stopped winching. I have a Sportsman 500 H.O. which is not real heavy nor very light . Tell me what you think.
Also the spool was backing off under tension slightly when not winching.

 

Sounds normal. That will not hold a load. The battery can be the problem with the pull. If you need a battery anyway, why not replace the battery and then give the winch another try? I find it help to clean the mud out of the gears and grease them every so often.

 

A weak battery can definitely be the problem. A winch draws a huge amount of power, and at idle I seriously doubt your stator is putting out enough juice all by itself for the winch. Your Sportsman has a more powerful electrical output than my Scrambler, but I had to add a second battery. Wired in parallel, two batteries still make only 12volts, but higher amps and much greater longevity. Where once my winch would barely pull me out of the mud, now it will easily lift the entire thing completely off the ground, over and over again. If a second battery is too extreme for you, consider a more powerful single one. If you need to replace yours anyway, talk to a good battery shop and see if there is a more powerful model that has the same footprint so it will fit back in the battery box. It may be that you have room for a taller battery that is the same width and depth, it all depends on your atv.

One other thing to check is the wiring to your winch. Are you running through a relay? Any wire has resistance, and the longer the wire the greqater resistance, and thus a loss of power through heat. A relay allows you to keep the heavy wires short, and use a light wire to switch it. Check all of your connections for corrosion and make sure the wire you are using is heavy enough.

As far as the winch backing off, some winches have an integral brake and other do not. Many of these smallers ones on atv's do not, so that is probably normal.