I am making a DIY Raspberry Pi laptop. So far I have found a suitable board that will drive my display (M.NT68676.2A). From research I have found out that it will run off of anything from 12 V to 5 V, and that it uses around 3 A (I am not sure if that's at 12 V or at 5 V). I've also found a 14.8 V 6600 mAH Li-ion battery from Tenergy that I'm thinking of using (5 A output max).
What's the best way of converting the 14.8 V output from the battery to a suitable 5 V for both the board (5 V 3 A?) and the Raspberry Pi (5 V 2 A) without wasting too much energy or spending too much?