Using a 400w DC to DC Step-Up Boost Converter to Charge Batteries Using Genset?

Hi,

I stumbled upon this on ebay while looking to build a custom 12v to LCD power adapter. There's also an interesting video review explaining how this thing works.

I am currently building a solar system with an 25 amp mppt charge controller doing off grid. I'm thinking of using this as a battery charger during sunless days and emergencies by connecting the boost converter between my small gas generator's dc 12v 8.3amp outlet and my charge controller. Essentially boosting the generator's dc power outlet acting as a surrogate for a set of 300 watt panels to the charge controller.

I know people would say to just get a charger but this thing is cheap and I think more efficient than to use a ac to dc battery charger. I can use my small genset instead of my big multi kilowatt genset. In addition I can use it as my LCD computer monitor power supply when it's not in use as a surrogate battery charger saving me money.Do guys think this will work?

Any reply and helpful advice will be greatly appreciated.