Saying a 21700 cell is safe for kids because it has a protection circuit is a lot like saying a 3000 mW laser is safe for kids because it’s throttled down to only 1000 mW. It can still cause quite a bit of damage in less than a second.

Yesterday I had a wire turn into smoke from an accidental short using less current than a protected 21700 cell puts out.

It’s usually pretty easy to find child-safe flashlights at local retail stores, if that’s the goal. But for enthusiasts, those lights are unappealing for precisely the same reasons they’re safe for kids. AA and AAA batteries make great training wheels… but it’s nice having the freedom to take the training wheels off and play with hot rods.

It seems a bit strange though, asking hot rod manufacturers to install engine governors. It kinda misses the point of the product they make.

I’m not sure why exactly ZebraLight stopped supporting protected cells, but I suspect it was probably a combination of factors:

  • To make their lights smaller. “Small” is a big part of their brand.
  • To make their lights brighter. “Bright” is also a big part of their brand.
  • To eliminate customer complaints about the light being defective because it shuts itself off on the high modes. The protection circuit trips and makes it seem like the light is broken… which can be anywhere from inconvenient to dangerous, depending on the situation. Resetting the protection circuit typically requires sticking the battery in a charger, which isn’t going to happen while changing a tire in the middle of the night.

I generally wouldn’t recommend giving kids any li-ion flashlights until they know how to be safe. But if you do, you should probably at least make it a relatively weak light, like a 3x7135 Convoy shorty with 18350 or 16340 cell. Definitely not a maximum-power “wow” light like a 21700 direct-drive multi-emitter nut roaster. That’s just asking for trouble.