After replacing the cigar box sized battery in my Mule for two years in a row (at a cost of about $80 per trip), I decided to mount a deep cycle group 24 behind the front seat.
Bought a sturdy battery holder, a couple of 32" cables and voila!....no more battery blues
I usually get about three years out of one of these.
Also installed a 2 amp trickle charger.
Me so happy.