So, just wondering, which battery tender is the best one to use for long term storage?

 

I've used these for years. Not cheap but good and reliable. The cheaper ones would probably work though.

 

I have used one of these for years >>>

Battery Tender on Amazon

Battery Tender on Amazon

 

My preferred method is to start the car and let it run, and cycle the top every three weeks.
If at all possible, I drive the car around the block a few times as well (but not if there is salt on the roads).

 

I use a Deltran Tender on my Crossfire, Harley, and Cub Cadet Mower ... never have had a problem

 

A storage suggestion. If you store your xfire for a long period of time during the winter months I would disconnect the battery and connect it to a tender. Occasionally starting the engine and letting run for short periods in my opinion does more harm than good.
Doing this creates internal condensate to form which can over time develop sludge and raise the acidic level of the oil.