[giarc]

Although that might be true, battery powered flashlights/torches suffer from the problem of leaky batteries. I've tried to use many flashlights that don't work, only to find the batteries have started to leak acid and ruined the flashlight. Sure, one should check the batteries every year or so, but who really does that? I'm not saying the gravitylight is a good replacement, just that battery powered flashlights do have some drawbacks.

[libria]

This is what lithium primaries are for; they don't leak.

[Vexs]

And before anyone jumps in and says "lithium batteries self discharge!" Yes, yes they do. But it's really, really small. It discharges quickly initially, but then tapers off to about 1% per month.