My wife and I now commute together so my Mini is not driven very often and I want to maintain the battery while it is stored. Excuse my ignorance, but will a solar charger that plugs into the lighter work? I am inclined to assume it will not since the lighter does not work with the ignition off... am I correct?

 

why not simply buy a trickler charger?
i used this for the whole winter and works great.
tons of them in ebay...el chepo!!
http://cgi.ebay.com/ebaymotors/NEW-1...Q5fAccessories

 

you dont want to charge your battery all the time it can over charge. You need a system designed for maintenence. Battery Tender is good.

This is the best

http://www.outmotoring.com/mini-coop...ng_system.html

I use this on my Shelby Mustang as well as my racing motorcycles.

 

wHAT? Trickler charger is automatic. When full, it does not charge.
this ain't 1960 trickler charger.

 

Regardless of the charger, you are correct that the lighter socket won't work. You'll need to tap into a constant 12v source. Solar would be a good idea if you are parked far away from an outlet or don't want to have to deal with unplugging it every time you want to drive after a few weeks of downtime. Otherwise I don't recommend the cheap chargers. Some are trickle chargers which do indeed stay on all the time or don't monitor the battery too well. The CTEK looks good and I've had great experience with the Battery Tender line from Deltran. I stick with the low amp ones since it will hold the charge fine where the more expensive higher amp ones are only better for recharging a low/dead battery in shorter time.