Frank, I would think that batteries are part of the "mass" of an aircraft and would be part of the weight consideration. Considering that limiting the weight of the plane to 55 lbs is an attempt to reduce the energy on impact, you would have to consider the flying mass. Strangly there is no limiting of the speed which has a far influence on the energy than mass. I suspect the inforcement is much easier with weight than speed.. Just a thought. BobH.