Review on SUNER POWER Waterproof Battery Maintainer Tools & Equipment and Jump Starters, Battery Chargers & Portable Power by James Cross

This 10w model connects via the fuse box with an extra plug. I used a multimeter to determine which pins were still live, even after most of them went dead after the car had been off for a while. It keeps my battery sufficiently charged for over a year even if I don't drive for a while, and even on short and cloudy days. The suction cups are very effective, but I usually only mount them on the dashboard. The charge indicator light is helpful and shows it's charging, as long as it's getting decent light it doesn't have to be completely sunny. The only negative actually is that the SAE connector is set up so that the open pin carries 12V from the car side, so I try to keep the insulator on the connector when it's not connected.