What to do with dead protected cells?

[ChrisGarrett]

@patmurris

Although i could save those six cells, thanks to the above mentioned trick, i’m a bit worried about all the lights i gifted with protected cells… If you manage to drain them so that the PCB protection trips (no LVP on the light, parasitic drain or self discharge over a couple years?), you may end up with a cell that won’t charge back at all!

You really shouldn’t be ‘gifting’ inexperienced people li-ion flashlights, cells, or chargers.

That’s what AA, AAA, C and D alkaleaks are for.

Many PCBs will trip at around 2.8v, some I’ve read even trip at a lower 2.4v, which even for lithium-cobalt, isn’t catastrophic. The problems arise when li-co (rarer these days) cells are left in a completely discharged state for long enough periods of time that copper ‘whiskers’ dendrites form on the separator and create a short upon charging.

This might have been a worry 5-10 years back, but not so much now.

Chris

[patmurris]

@ChrisGarrett

@patmurris

Although i could save those six cells, thanks to the above mentioned trick, i’m a bit worried about all the lights i gifted with protected cells… If you manage to drain them so that the PCB protection trips (no LVP on the light, parasitic drain or self discharge over a couple years?), you may end up with a cell that won’t charge back at all!

You really shouldn’t be ‘gifting’ inexperienced people li-ion flashlights, cells, or chargers.
That’s what AA, AAA, C and D alkaleaks are for.

I get the argument but when the cell is inside a USB (or else) rechargeable light, it’s far less of a worry. A bit like the dangerous amount of gasoline inside a car tank. It usually doesn’t blow up and we acknowledge the risk in the face of convenience.

[klrman]

@patmurris

I get the argument but when the cell is inside a USB (or else) rechargeable light, it’s far less of a worry. A bit like the dangerous amount of gasoline inside a car tank. It usually doesn’t blow up and we acknowledge the risk in the face of convenience.

That being said, I'm always a little nervous when I replace an electric fuel pump in my car's gas tank.