I have one similar to this, but no air compressor. But it did have a smart charger to it so you could see the percentage on the LED indicator and could leave it plugged in. Made by Diehard. Was a great investment, since my Girlfriend had her 98 VW Beetle Diesel and in Michigan, it worked great to start the bastard in -20 F temps. The Battery was still good, just the vehicle at that age and miles, it would take an extra 15-20 mins to restart the glow plugs and crank. (Didn't have the option to use a block heater).