What I meant was that internal, proprietary battery "packs" eventually cannot be replaced. When those give up the ghost, it's tough on an owner, especially with older unsupported models of lighting.

But owner-swappable individual battery cells can be easily replaced. And those older cells can be replaced with newer-style batteries of the same type that handle greater draw, last longer, can be cycled more times before fading. Going from a "standard" off-the-shelf alkaline to a newer top-end NiMh cell is easy. Going from one to a good rechargeable Li-Ion is easy. Getitng a better Li-Ion rechargeable when that older rechargeable begins to tank is easy. So long as the basic lighting unit isn't hamstrung by only allowing a certain older kind of cell.