OP: Not mentioned in any post, but all depends on the availability of power where you store your trailer. If at home or if you store your rig away from home and power is available, placing a maintenance charger like the Battery Tender or Battery Minder is a good idea. Our trailer is in a storage facility with no access to power, so I bring the batteries home and place them on a maintenance charger in the garage. Solar charger setup might be OK if the collector panel gets good sun exposure, but I could buy several Battery Tenders for the price of a solar charger............and my trailer is stored under cover.