I thought I was pretty smart about batteries since my Dad sold them and I worked around them most of my formative years. Then I bought a NEV (neighborhood electrical vehicle) and began looking into batteries and prolonging their lives and found I didn't know squat. If you really want to know about all the various types (full float, AGM, maintenance-free, etc) Google "deep cycle battery" and you'll find a wealth of information that will dispel old wives tails and give you a very good knowledge base. A couple of things to remember. You should not - ever - run a battery to discharge before recharging (the wives tale of - you should discharge the battery completely once a month and then recharge it to maintain long life). Batteries are measured at a standard temperature for their number of cycles at a 50% DOD (Depth of discharge). So a battery that costs more but has a larger number of cycles may be a better buy than a cheaper battery with fewer cycles. Optima falls into this cheaper, fewer cycles category. Always recharge immediately after use (your quad will do this when you ride, but if you always use a trickle charger, charge right away after use - every time). Those trickle chargers from Del-Trans (sold at Cabela's as someone mentioned) are EXCELLENT and will keep a battery alive for a very, very long time (the small, motorcycle one is .750 amp, the larger one is 1.25 amp). True story - I kept a battery working for 16 years using one of the Del-Trans 1.25 amp chargers (it got signifiantly discharged and died immediately). An AGM battery cannot recover from a significant discharge if left discharged (like a quad in storage for the winter). Oh, BTW, if the battery is DEAD, you cannot start and run your machine by pushing or pull starting. This is because, if dead, there is NO (as in NONE) current between the positive and negative terminals so the machine cannot run. It's like a short. Anything above dead (however slight) and that is not true. Installing a low, or partially charged battery is not good for your charging system. This is because the charging system has to work like crazy to bring the battery up to charge. Charge it completely first. Don't believe that - lay your hand on your car/truck's alternator. If you've got a new, fully-charged battery, the alternator will only be warm. If you've installed a low charged battery the alternator will be too hot to touch. How do you suppose that will affect the life of your alternator if repeated often enough?