How so, exactly? There's no way for anyone to check how much a battery was charged regularly, just like there's no way to check if a car was only used to drive to church once a week or driven like a hooligan hitting redline all the time - I'm not suggesting fraud of course, far from it - just that buyers have to assume the worst possible use case, and if so I don't see how actually regularly charging the battery to max affects the resale value at all. Besides, I don't expect the resale value to be very high after 8 years(realistically more) anyway.