Very interesting solution indeed. The advertisement says 35 watts power consumption. I'm thinking about converting that to amps and calculating how long an Optima deep discharge marine battery might keep that going before requiring a recharge. What I am thinking of is leaving off the solar charge option because of the inefficiency of the cheap solar chargers and the great expense of the ones that would provide a useful charge. If I could get away with just recharging that battery once a week, that might be a viable alternative.

You could also just add a second battery to your vehicle and add an isolator switch to make sure your fridge does not run down your main battery. This would allow the vehicle alternator to charge the additional battery. Although I suspect that this option may only be available to truck and SUV owners with over-engineered alternators.

Craig.