There's some sense in which I prefer this, though, because at least I know how to source D batteries and they're a commonly available standard and I know exactly what their shelf life is. I might even have spares around in my emergency kit for things like lanterns and radios. I've also seen Verizon battery backup units that run on small lead-acid batteries which seem to need frequent replacing, and require me to look up the details and order from a specialty vendor every time... more annoying to keep extras of those on hand and tough luck if it reaches end of life shortly before or during an emergency.