Which 21700 cell for each of my lights?

Hi everyone,

I am looking for some advice and guidance please on which of my 21700 cells would be best suited to each of my 21700 flashlights. I, personally, would prefer output level first followed by runtime.

The lights I currently have are:

Astrolux EC01
Convoy S21A
Sofirn C8F
Sofirn C8G

The cells that I have available are:

Molicel P42A
Molicel M50A
Samsung 40T
Samsung 50G
Sofirn 4800mah
Sofirn 4000mah

Thank you very much.


There are many good ones. I have been using the MOLICEL/NPE INR-21700-P42A with good results.

I’ve been messing around with building Ebike battery packs —-I’ve been using these Tesla Model 3 (panasonic ) cells —-they don’t push a light quite as hard at 4.2v as a Samsung 40T but in the range of 3.95v — 3.3 v they drive lights harder —these cells come from defective Tesla modules that were never used —Quite cheap to

here’s one example


I’ll try to rank the flashlights by how much power / current they use on Turbo modes.
Then try to rank the batteries by which is more high-drain (less voltage sag).

Astrolux EC01
Convoy S21A
Sofirn C8F
Sofirn C8G

based on my measuring tailcap current of the above flashlights on highest brightness level, I got these results (give or take a little variance since I’m just using the Uni-T UT210E clamp meter and a short piece of wire)

flashlights that consume power (roughly ranked from least power to most power consumption)

Convoy S21A (SST40 variant) - uses around 5-6 Amps on max output
Sofirn C8G (SST40 variant) - uses around 5 Amps only on max output (not very sure if this is correct, but my unit uses a lower current than the C8G XHP35-Hi)
Sofirn C8G (XHP35-Hi variant) - uses around 6 Amps on max output
Astrolux EC01 (SST40 variant) - uses around 7 Amps on Turbo

Sofirn C8F-21700 (XPL-HD & LH351D variants) - these can use around 10-12 Amps on Turbo
Astrolux EC01 (XHP50.2 variant) - uses around 12-14 Amps on Turbo


batteries that can provide most power to least power (roughly) ; basing from HKJ’s test result, and other sources (Sofirn 21700 batteries do not seem to be the same — I noted at least 3 different types of 21700 for their Sofirn 4000mah 21700, which probably perform slightly differently)

Samsung 40T = high-drain, just slightly more powerful than P42A
Molicel P42A = high-drain, just slightly less powerful than 40T

Sofirn 4000mah = unknown, but seems to be a bit similar to Lishen 4000mAh 21700 (??)

Samsung 50G = high-capacity ; supposed to be just slightly better than M50A
Molicel M50A = high-capacity; supposed to be just slightly worse than 50G

Sofirn 4800mah = unknown, but seems to perform OK


given the above rough infos,

and the goal is for brighter output (and not exactly longer runtime)

I’ll use the 40T and P42A on the Sofirn C8F-21700 and the Astrolux EC01 (XHP50.2 variant), since these 2 flashlights use more than 10 Amps when on Turbo. The 40T and P42A will have less voltage sag on Turbo.

The M50A and 50G are for longer runtime, and wouldn’t mind too much for the flashlights that use lower power consumption - eg. the single-SST40 based flashlights or the C8G XHP35-Hi.

The Sofirn 4000mAh and Sofirn 4800mAh probably will be just slightly less performance and runtime than the M50A / M50G.
The Sofirn 4000mAh 21700 is not a high-drain type like the 40T or P42A, even though they have similar rated capacity.


if your goal is the flashlight has longer runtime, and don’t mind slightly less max output on Turbo mode (will also mean a slightly less hot flashlight), then use the M50A and 50G on any of them, or the Sofirn 4800mAh.

Hi everyone,

Thank you very much for all taking the time to reply.

d_t_a - you have given me a lot of information there :slight_smile:

And I will check out the link for the Tesla cells.

Thanks again,


Hi… if i may ask where can i buy the original molicel 21700-P42A. Thanks

Here's where I got mine:


Other sellers can be found here: