After buying too many batteries for my ATV's over the years, I'm thinking of using solar to trickle charge my ATV batteries when not in use. I store my 3 ATVs in our garage at our offsite cabin, where temperatures gut up into the 90's in the summer, and in the teens in the winter. I only use the quads once a month, and too frequently they've been getting drained down due to the limited use and temperature swings.
I'd like to set something up where I could connect each quad to a solar trickle charger when I leave, so the it maintains the batteries while I'm away for each month. Since I'll need three of them (one for each quad), I'd like to keep it as simple and cheap as possible. The ATV batteries are fairly large (for Polaris 500 EFIs) One option appears to be a 1W panel that I can wire directly to the battery w/out a charge controller, and another would be a 5W panel that may/may not need a charge controller. Both are for sale by our sponsor. What I'd like some input on, is whether or not the 1W would be sufficient, or if not, whether the 5W would need a charge controller. My other concern is how safe these are, since they'll be connected and unsupervised at our remote cabin while I'm away for ~1 month at a time. Overcharging and any risk of sparks, fire, etc. is not anything I want to deal with.
Any advice/thoughts any of you could offer would be greatly appreciated. Thanks!