Most of the newer batteries are sealed and have a condition eye. This eye should be either green or blue. If it is black then this indicates a low charge. If the eye is clear or yellow, then the electrolyte is low and the battery needs to be replaced. This may also be a sign that the regulator is over charging the battery.
Exhaust system Look over the exhaust system for any lose bolts, loose mountings or cracks.
Cracking around the muffler inlet or outlet is common. If caught in time this could save you from losing part of the exhaust system on a trail. Seeing a muffler on the side of a trail is not uncommon. In knowing what to look for, you can check the condition of your transmission and axle gears, by looking at the fluid and not just checking the levels. On the drive axles the fluid is checked at the plug hole half way up on the differential housing or cover plate.