Doing some forward planning for the wintertime. I searched but all I could find was some old threads about the best current Battery Tender/Trickle Charger. I would like to buy one and would like some direction on which one to get. I try to drive my Elise once a week but the battery didnt have full charge this morning so I had to jump her. Any suggestions on a Battery Tender? My battery currently has a charger port on it but did not come with a Tender.