This is a concern. The battery for my plane is more like half. Doing a little research into it, it seems like lithium batteries have a very flat discharge curve, maintaining voltage until they are empty, and doing so consistently even at higher draws. Apparently a 35AH L/A will provide 1 amp for 35 hours, but increase the load to 15A and it's far less than the 2 hours you'd expect, with the voltage dropping off faster as well. Supposedly the EarthX was sized to provide a similar usable reserve to the original L/A. TBH if the choice was between a 5lb 15AH battery and a 10lb 30AH, I'd take the latter. As it is, they show an hour or reserve at 15A, which is about what my plane runs normally. I always assumed I'd get about 30m out of my L/A, so I guess I'm comfortable with that.