What is the difference? Convoy M21B with 3V XHP50.2 vs M21B with XHP50.2?

I was browsing Simon’s store wanting to pick up a M21B flashlight but I came across two very similar lights and am not sure how they differ.
Links below:-

Convoy M21B with 3V XHP50.2 6500K

Convoy M21B flashlight with XHP50.2 @ 6500K

If both lights are 6500K with an OP reflector, could someone please enlighten me on how they are different, or why if one is better than the other.

The second one with 6V XHP50.2 has a boost driver (XHP50.2 are 6V LEDs unless otherwise specified). That means that the runtime will be longer and will heat a bit less than the 3V version(which has a linear driver). The output power looks to be the same (6Ax3V vs 3Ax6V, both equal 18W).

It’s possible that the 6V version may be unable to reach turbo when the battery charge is low, that’s a common issue with boost drivers. At some point the 3V version won’t either, I’m not sure which version will reach that point first.

Overall I think the 6V version would be better.

If you have test equipment you can buy both and experiment on them :smiley:

Thank you.

No test equipment. Not even sure how to experiment. Complete novice here.

Probable issue with the step up regulator is minimizing cost of components. Inductor, maybe output capacitor. I may learn something here. At first I thought flashlights were using linear regulators (drivers), but have seen so many comments on PWM drivers. Are both being used; linear and pwm drivers? I guess I should not be surprised.


The answers given above are correct about the drivers being different. But, let me word this a different way.

The reason for the different drivers is due to the first linked XHP50.2 is a 3V (requires 3 volts only to power it) XHP50.2 LED and Simon only offers it in 6500K.

The second linked XHP50.2 is a 6V LED (requires 6 volts to power) and Simon offers it in 3000k, 4000k, 5000k, and 6500k.

Personally i opted for the 4000k color temp M21B solely based on not wanting the 6500k color temp. It's all a matter of preference, I'm not a color tint snob, it's just that 4000k is much more pleasing to my eyes.

Most flashlights using 7135 chips like the older Convoy models use the 7135 to obtain the 100% mode current and then use PWM over that current to obtain the lower modes. The disadvantage is that efficiency doesn’t improve when using less than the 100% mode, the advantages are better tint consistency between modes (at low constant current LEDs get greener tint but efficiency improves) and lower cost as 7135s are mass produced parts.

The driver used in the M21B 3V uses a FET to archive linear regulation rather than 7135 chips, like the one from Led4Power, that allows obtaining the lower modes without PWM, but extra voltage is still wasted as heat like in traditional 7135 linear drivers. I wouldn’t call it a FET driver because in this community when we talk about FET drivers we usually mean the simpler, higher output ones, which let pass as much current as possible and obtain the lower modes with PWM over that huge current, resulting in poor efficiency when you don’t need turbo (more than one channel like 1+FET will improve the efficiency of this setup).


Please take a look at this review: Convoy M21B Flashlight Review - ZeroAir Reviews

There is a chart which shows the lumens output on high mode. It’s constant until minute 110. Can you tell from the whether the M21B version reviewed by Zero Air features a 3V or 6V driver? Would the charts look different when using a 3V or a 6V driver?

Thank you very much!

This is review of M21B with SST40 not XHP50.2 LED. I have only M21B with FC40 5000K and it is great. Yesterday I tested it with fan cooling and M21B can sustain stable about 1600 lumens for about 40mins with fan, without it will stepdown for about 1100 lumens for 60-70 minutes that with new Samsung INR21700-40T batterry. M21B is great little host with very good thermal capabilities.

Good to hear that you are very glad with your FC40!
There are two versions of the XHP 50.2 to choose from: 3V or 6V. I’m wondering if their lumens output might be different. I want to make sure that the output is quiete constant in the high mode as shown in the review of the M21B SST40.

I have XHP50.2 in SP33 v 2.0 light which is 6V variant and also have EC01 with 3V variant. Both are cool white version. I will compared them side by side this evening. But the Convoy driver is current limited so you can’t except full power of 3V variant. With FET and turbo mode 3V is more bright and I think it was about 3500 lumens compared to 6V variant because boost driver is not powerful enough to make more output current. In best you can try to use 5A boost driver for XhP70.2 which Simon use also for 6V variant of 70.2. Boost driver is more efficient compared to linear also with 6V you will have more choices for color of LED and very good constant output.

Hello icpart!
Thank you very much for your effort! I just finished an analysis that revealed what I wanted to know. I installed an application on my smartphone which can track lux/lumens over time. I found out that my Convoy M21B XHP 50.2 3V delivers a fully flat lux/lumens output on high mode over the entire life span of the battery (not turbo!).

What are the lumens achieved at that constant output?