The grip and display are poorly designed, not what you would expect from a reliable $200 charger. The device should have reverse polarity protection, but it doesn't work. When I put it in boost mode it never applied power to the 10 volt battery, the fan turned on but I held a voltmeter to it and it never started charging. I read and followed the instructions but it just didn't do what it said it would do. I never tried the boost start feature, I learned enough just trying to charge the battery. The electronics in this device are of very poor design, NOT BAD! The scrolling display consists of a technology that was used 30 years ago. You could use the LCD very easily and make it look a lot better.