16340 in series

[Burncycle]

Was looking into getting one of these.
https://www.lumensfactory.com/en/product_detail.php?pid=365

Originally was going to use a single 16650 in lieu of 2x CR123 or 2x 16340, but because the cutoff voltage of the driver is relatively high, I guess runtime suffers with the single battery (40 min vs 1 hour - 1.5 hours for the other solutions). Is running 2x 16340s safe in general, should I look for certain features to make it so (chemistry, protection circuits, etc) or do I really need to be on top of it and match voltages with a multimeter after charging to ensure it's not going to turn into a firecracker in my hand

 

[Katherine Alicia]

Li-Ions in series need a protection circuit, anything else is just dangerous.

 

[chillinn]

...but because the cutoff voltage of the driver is relatively high, I guess runtime suffers with the single battery (40 min vs 1 hour - 1.5 hours for the other solutions).

If I have this right, especially because this is single mode, it would be because the amp draw doesn't change whether you're running a single or double cells, but with 2 cells the amps are split between two cells, so runtime is longer with 2 cells.

Li-Ions in series need a protection circuit, anything else is just dangerous.

I agree. Surefire primaries and US made CR123A all have them. LiCo ICR secondaries do not always have protection circuits, but they should, every single one. IMR and INR secondaries do not come with protection circuits. I run INR18650's in series in a light for FM1794, 3A, no protection. Thermal runaway is a risk, but the cells don't get all that hot, but the host, a Leef, has some mass and is pretty thick metal so heat transfer is pretty good, and it does not get hot. The M3 head gets hot, of course.

 

[ChrisGarrett]

If I have this right, especially because this is single mode, it would be because the amp draw doesn't change whether you're running a single or double cells, but with 2 cells the amps are split between two cells, so runtime is longer with 2 cells.

16340s have crappy capacity/energy density compared to a single 18650.

No bueno.

Chris




I agree. Surefire primaries and US made CR123A all have them. LiCo ICR secondaries do not always have protection circuits, but they should, every single one. IMR and INR secondaries do not come with protection circuits. I run INR18650's in series in a light for FM1794, 3A, no protection. Thermal runaway is a risk, but the cells don't get all that hot, but the host, a Leef, has some mass and is pretty thick metal so heat transfer is pretty good, and it does not get hot. The M3 head gets hot, of course.