I'm not a very popular poster these days but this is what I do. I have three Battery Tenders (that’s the products name) for my car, bike and quad. Their an automatic battery maintainer that keeps you battery fully charged, without overcharging, and you can leave them plugged in all winter long. The Battery Tender will come with both clips and stud mounted wires. Use the stud mounts for positive/permanent attachment. The wires are about 2' in length with a polarity plug on one end. Once attached you can close up your battery cover and run the wire out between the hood and windshield. Now you can close your hood so the hood light won't be on and the wire will be sticking out. Plug the Battery Tender into a wall socket and then plug in the charging wire and place it on a shop towel on your winshield wiper arm. The lights will tell you its charging or in stand by. Plug it in when ever your car is going to sit for a while. You won't have to keep a door open or window rolled down or your hood open.
This will save your battery and extend its life. You can get one at any auto parts store, remember this is not just a trickle charger.
http://batterytender.com/product_info.php?products_id=2&osCsid=886ba73f788ced70045b410e0805a318