A little help needed

Hey everyone I took my new to me 2010 RZR800 out for my first trail ride today. Learned a few things, like tires are too big, clutching is off, suspension is too soft…..

But here’s the one I’m asking for help with, at the beginning of the ride the battery light kept flashing from time to time. It was about 40 out and I hadn’t had this on the trickle charger for a bit. Anyway it eventually went away or I was having too much fun to notice but at the end of the day I noticed while decending some monster ski hills that the tach was reading 0 and the idle was pretty low.

I’m an old school guy so these are new to me, please point me in the right direction.

Thanks RZR masters 🙂