I have been using the Batt Tender Plus for 20 yrs. My first one wore out after 11 yrs. Now Im on my second one. I have this connected during the entire winter and when its parked in the garage in the spring/summer. I like it and it does charge agm or gel batt. I do use a Ctek for my Honda generator. I like them both. Im sure the others mentioned are good to. Don't get a cheap one. Lots of reviews if you check online on other units mentioned.