The 94% efficiency is where you are losing the energy for what it's worth. I didn't think of Andy, he's got good stuff too. I buy 100% of my leads from him, never had one with a "loose" connection. Actually, now that I think about it, the energy lost in bringing the voltage down is not "more" it's just what it is to get to the voltage you want. 5.1 is more lost than 6.0. I don't know what the efficiency is of the regulators we use, but I could get 7 bonafide flights out of my duralites in the euro (9 minute flights) on one charge.