The reason I own a Battery Tender is so the over all life of the battery will be extended. 2-3 times longer life according to the manufacturer. Last winter I'd leave my RS unattended with no Battery Tender, sometimes for a couple of months and it would start fine. But over the years the battery doesn't bounce back so well. A battery tender just keeps it in better shape, so it lasts longer. And, if you ever do lose your charge, it helps charge it back up if there is still a trickle of life left in it.