"BEU" sounds like a valid time constant, but there are many variables. I consumed three beers this evening in the time it took another pilot to handle only two. Obviously, the BEU needs to be correlated with time- like a 12 A/Hour battery or something like that. Not all circuits (or pilots) draw amps (or beer) at the same rate. I have heard that Mormons, for instance, have a rather low BEU/Hr consumption rate unless you only go camping with one of them.