have two bikes and two cars in the garage- all are on battery tenders if i am not in them... the edge is outside and not on a tender (yet)- any that will sit for a coupla days should be on a tender, imo. forget chargers- tenders monitor the battery and wont overcharge them. the 4 garaged vehicles are 2005, 2000, 2008 and 2005- all orginal batteries. tenders work- i also have "pig-tails" on all vehicles (they just plug in to the tenders in the garage- no fancy hook up needed).