X2. Hands down one of the best purchases I have ever made. I have saved many batteries for friends with it and my GN stays plugged in always and my battery feels like new every time I start the car.Here's what I'm using Kevin.....works great!......can't say enough about it
I'm using the Optimate 6 Desulfating Charger / Maintainer.
http://turbobuick.com/forums/threads/battery-chargers.338790/#post-2690979
http://tecmate.com/products/optimate-6-ampmatic/
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Agreed.........Battery Tender Plus. Never a problem in 4 years of use.Battery Tender Plus and never look back.