【convoy】M21H bezel available now

Thanks Barkuti

A few minutes ago I finished modding my ∅17mm SST40 biscotti clone drivers, one of them will (hopefully) go in an old, modified Thrunite T20T and for this reason I removed the stock spring (there's barely place for a copper top cell driver contact inside that tiny flashlight).

So I grabbed a couple BlueSwordM's springs, 3rd and 2nd gen big springs, and proceeded to make a crude voltage drop over the spring test against the new springs Simon is using in the biscotti clone drivers. I used my precision power supply tuned at 5A, with alligator clamps attached to the ends of the springs as best as I could. Connecting at the base of the springs was easy, the top gave me some difficulties, and I placed my multimeter's probes as best as I was able (near the base beside the clamp and as close to the top as I could make a decent contact):

  • Newer wide top spring from Simon: in a first run I was getting 60 - 65mV. Tried two more times, got values jumping up and down up to 70 and below 60mV. On average, I give it a rough score of 62 - 63mV of drop.
  • BlueSwordM's 3rd gen big spring: could see some figure above 60mV, but all around 57 - 58mV give or take rough drop score.
  • BlueSwordM's 2nd gen big spring: this was fast, could clearly see figures settling around 45 - 46mV rough drop score. Bear in mind the 2nd gen spring has one coil less than the 3rd gen, and it somewhat deforms once compressed.

Now, despite the limitations of the test and the possible percentage of error, all I can say is the stock springs coming with the newer drivers are awesome! Let's wait to see what Simon has to say, but they must be made of C17530 or something with similar IACS conductivity to perform this good. It's either this or I did some blunder with my procedure, although I don't (yet) see how.

Thu, 05/21/2020 - 21:46

Thanks for the tests! I’m really not keen on spring bypasses so it’s good to hear Simon is now using some nice high current springs on his drivers. Hopefully he’s done the same with the tail springs.

yes,phosphor bronze.

Its internal resistance is very small, no need to add bypass.

the ramping driver is not linear ,the max output current can reach 8A

Phosphor bronze? I wonder, though, why it does so good conductivity wise. Or at least it did very very good in my quick test.

Excuse me Simon but the ramping driver is linear, employs the onboard MOSFET as a variable resistor by tuning the gate voltage using the voltage drop at the sense resistor to regulate. Exactly like in the other SST-40 sequential mode selection drivers.

Regarding the springs used on Convoy flashlights… I noticed something recently.

I have an older Convoy S2+ SST40 (6500k) and a newer Convoy S2+ SST40 (5000k), both are the 4-mode driver version.

I notice that the older version has a thinner spring, but with spring-bypass wire. Whereas the new S2+ SST40 spring look like the ones posted above.

left: new S2+ SST40 (thicker spring, without spring-bypass)
right: older S2+ SST40 (thinner spring, but with spring-bypass)

Any idea which one is better: performance & durability? (I think they seem to perform similarly in terms of tail current measurement…)


How many amps are you throwing through it? It’ll probably only make a difference at >7A or more.

It should be because the spring is thicker and has fewer turns.

I’m not sure if we are talking about the same driver.

Yes, we do. R005 sense resistor onboard. A sense resistor is pointless in an unregulated MOSFET driver.

Whack an R005 on it, 7.5A in an S2+ SST40 :wink:

Simon, can I PM you my order number to extend the Buyer Protection? I thought I sent a request through AE but don’t know if it got there; apparently my order will “close” in 2 days.

Okay, so in that driver, an R010 gives 5A. The R010 is 0.01 Ohms, so using the table here:

Punch in 5A and 0.01 Ohms gives us a sense resistance voltage of 0.05V.

Hit reset, put in 0.05V again, then change the resistance - given these kinds of resistors only come in so many varieties (eg. R020, R008, R005 etc).

Calculate 4 digit SMD resistor: R005 (as an example - click to get the one you want to check)

So 0.05V with say, R020 (0.02 Ohms), shows as 2.5A. If you solder an R020 resistor in parallel onto the R010, it’ll give an output of 7.5A (or around it). R025 would give a total of 7A, etc etc.

The issue is getting the exact size of resistor or at least close to it, and a pack with different resistances!

It kinda pushes them pretty hard. My guess is that Simon goes for reliability over maximum power; same way that car manufacturers detune engines so they’re reliable. Makes sense; I’m just glad there’s a way we can do that if we want.

Different sense voltage on the 6A drivers (0.06v instead of 0.05v).

I’m not sure what size is on that driver though; I’ve got some coming but they’re not here yet. Someone else may be able to enlighten.

pls tell me the order number in PM ,my friend

If you have such a requirement, I can replace the spring for you before shipping.

Because no good factory was found before, or the flashlight did not use a particularly large current, it will take some time to completely replace the spring.

… a sense voltage of 0.05V.

2512 imperial? Wrong size.

∅22/20/17mm driver pictures can be found here (NTC resistor or temperature protection removal thread):

The ∅17 and ∅20mm drivers use a 1210 imperial size sense resistor (3.048 × 2.54mm theoretically). The ∅22mm driver uses a bigger chip resistor, and can be clearly seen that it must be a 2010 imperial (a 2512 looks like it would fit, though).

Sorry Barkuti, was typing on my phone while doing the shopping :slight_smile: daughter going crazy so I was bound to make some mistakes. I’ll go edit it now so it’s accurate for future reference.