The M6 is what we refer to as direct drive. There is no current or voltage regulation. See my post #2 in the ‘How to get max amps out of one li-ion cell’ thread for a little more detail, but still not a ton of detail.
Correct, current regulation will not help maintain the output: first the batteries are too weak and then there are the other considerations you mentioned. It’s important to know though, because in an actual regulated design you do not depend on sag. In this design you do.
If a person were to feed the light from a high-current power source which provided much over 4.2v the LEDs would likely poof. They might poof even at that voltage after a little bit, given that increased temperature drops Vf… actually yeah, I think they’d almost certainly poof at a constant 4.2v in an M6 or SRK.
I have a light that pulls 16A from one of these “weak” cells. My M6 has 4 of the same cells. So how are these cells so weak? 18A pulled from 120A offered. Essentially 4.25A per cell, not a lot to ask of one of todays high discharge offerings. 10V of draw from 16V of source, again I wouldn’t think that would be a weak supply. The main enemy here is heat, of course.
As far as the question about direct drive, yes, these are considered direct drive. The FET allows all available current to flow in Turbo mode, there is no regulation.
You’re touchy about that term!
ToyKeeper said that there would be no marked difference between DD and regulated here. She’s correct.
- In the DD setup light output will fall as the cells discharge. The resting voltage and the load voltage are both lower than what is required to get maximum light output.
- In a regulated setup it’s typically even worse. The cells still provide a relatively low voltage, but now we have a sense resistor dropping 0.1 to 0.2v also! At the high drive currents being discussed (such as 18A) the cells cannot maintain a high enough voltage for the driver to stay in regulation. This lack of ability to maintain voltage is what I’m describing in simple terms as “weak”. A strong PSU, such as a bench PSU, is a different story. It will maintain exactly the voltage it’s set to even at high current draws. A strong bench PSU set to the max charge voltage of a Li-Ion will poof a DD setup. It would also (hypothetically) allow a current-regulated 18A driver to maintain 18A output at a low Vin such as 4.2v, but of course that’s when the other factors Toykeeper mentioned come into play… light output would still go down and in an SRK or M6 the device would become too hot at some point.
(not touchy, just curious)
There are 3 emitters in the M6, with a Vf at up to 3.6Vf if pushed hard. There are 4 cells in the M6, with 4.21V on tap to begin with (when using high discharge IMR cells) I’ve tested these with a massive load from an MT-G2 and these cells can fall to 3.81V with load, IF the load is big enough. With 3 emitters pulling 6A each at the 3.6-3.7Vf range, there is about 18A pulled from these 4 cells, not enough to drag em down that hard. Not even enough to really drag down a 3400B for that matter.
Just trying to understand how the IMR cells are “weak” in a light like the hard driven M6, with 4 cells feeding 3 emitters. Seems to me there’s ample overhead and in use, it seems to play out that way. I’m probably missing something, as usual.
You are missing something important. 
- I was not referring to any particular cells, but all 18650’s.
- All 18650 cells are much too weak to maintain a high enough voltage for regulation at the drive currents we are discussing. That’s why regulated drivers are not made for this scenario. The context of my use of the word weak was specifically in regards to maintaining a high enough voltage for regulation. They can’t do it.
Also worth thinking about: I think your Vf estimates may be low. Both djozz and Match show much higher Vf numbers than what you mentioned.
EDIT for a little more info.
In order to maintain regulation Vin must be higher than Vout PLUS the sense voltage. Let’s call the sense voltage only 0.1v, although it’s often going to be even higher! With Efest IMR18650 2500mAh (Purple) 2014 you’re looking at an instant drop to 4v at 5A (closest graph to 4.5A per cell). Consider that you’re dropping that down to 3.9v because of the sense voltage. You’re already out of regulation and you haven’t even started!
Hi Richard,
Are you still accepting international orders via PM?
Not sure if mine made it through to you a couple of days ago.
Cheers.
Hi Richard,
Are you going to stock the new cree xp-l emitters?
Thanks for all the replies!
I have read about how to change modes but how does one swtich it off and on?
Is there memory for the modes?
Thanks
With the STAR firmware “Off” is just a mode. Short presses take you forward through the modes and long presses take you backwards through the modes.
Thanks wight, you’ve been very helpful.
Does this mean that to switch it off, I have to scroll trhough all modes ala Sky Ray King? Or unscrew the head from the body for lock out?
This seems to be a deal breaker for me….
Offhand I can’t confirm the body lockout (I clearly haven’t used my M6 much). I’m pretty sure the M6 has nice anodized threads and body lockout is fine.
You do have to scroll through the modes, the idea is that you are never more than a couple of clicks away from off - and even if you overshoot you can go backwards with this firmware to get back to off (long presses). I haven’t got STAR on my M6 - I haven’t used the momentary STAR firmware at all yet. So I can’t put in my 2 cents about how it works. Other seem happy with it, the majority of the people asking for “direct off” seem to be people who have not used it yet. That said, I’m sure there are those who have it who are unhappy!
Lol that’s definitely me! thanks again.
I’ll wait for Richard to chime in about the software. I read Richwouldnt is asking him for direct off from V2.0?
I've been using it, and I want direct off too. Covering up a light with your hand or leg or something works fine for smaller lights, but this thing gets surprisingly warm just in the few moments it takes to get back to off.
I have asked Richard to include the “Direct to off” feature and the mode memory he described as having tested in my new M6 light. In a PM to him I pointed out that the new features are not yet listed on his order page so it is unclear what version of the star firmware is now standard. I included the new firmware request in the comments area of my order and do not want the new light without it. When the new light arrives I will have both UI versions to compare in otherwise identical lights but I am pretty sure already which I will prefer.
With the older firmware the mid brightnesses are only approachable from min or max, then there were multiple switch presses to turn things off, while with the new version if there is a mode you commonly use it is the one that you get at turn-on if it is the last used when the light was turned off. When on the direct to off then allows single switch press “off”. A total of two switch depressions to use the light in a mid mode compared to the multiple presses required with the older firmware version. At least that is my understanding of the new firmware.
When the new order arrives I will have four M6 lights, a stocker, Richards Mod 1 and two of his M2s with the different firmwares. I consider the modification option 1 for $10.50 to be a best buy.
I’m about to order the Mod 2 M6. I can only see the listing with 4C plus some other tints. I was thinking about a 3C because my Convoy L4 is a 4c and it’s a bit on the yellow side for my liking. I’d like something a little whiter and cleaner. I know some other people have ordered a 3C before.
-Are there any performance differences with 3C or is it just the colour?
-Is 3C available for order? Out of stock? Takes longer to build?
On the M6, just about as soon as you break the snugness the light goes out. Or on mine it does. Very little movement required, as the contact is in the end of the tube so it immediately separates when you start to unscrew it. I think Richard says his light has been on/off so many times it doesn’t lock out anymore, so wear and tear might become an issue in that dept.
Backing into off is easy from the lower modes, quick from the 2 highest to forward into off. Or simply give the tube a slight twist. You definitely do NOT want to hold your hand over it in high or Turbo! Might get away with it against your leg through jeans or something but it would certainly be something you’d want to run through and not linger. I burned 3 neat holes in the lining of a jacket by turning it on for a few seconds in Turbo.
Performance , or output, is in the bin number…T6 vs U2 or U3. The tint should not really affect the output performance but there may be normal deviation within the performance bin level.
aoeu, lower tint bins have a little lower light output. When I get confused trying to configure a light at RMM’s store balancing what I want versus the stock on hand I check his listing of LEDs that he sells. The description has the Kelvin rating and the output rating. I would not worry about the performance variation. That difference is not visible to the human eye. The incredible volume of light will blow your mind and make you giggle like a mad scientist. I see some 3C XMLs in stock. Order quick.
Someone else asked about the ability to turn the head and lock out the light- yup, it works good. I turn mine about 1/4 turn and test it before tossing it in my pack or wherever it might get jostled.
Enjoy!
My Mod1 M6 doesn’t lock out. The threads are a little buggered up and the anodizing is missing from a spot. Pretty sure it’s from the factory, not Mountain Electronics and it’s not at all unusual for less expensive lights like the M6.
My M6 is flawless, literally. On the other hand, the SupFire L6 I got recently from a friend was far from that. It had a gouge in the white plastic emitter cover panel and under that the aluminum star was seriously gouged on top. There was thermal compound (fujik?) showing, dried in a few spots at the edges, on the bottom of the aluminum star, but none on the shelf between the two, with the shelf scraped and scarred where it’d been cleaned off. Someone had obviously had a go at modding this light, but it came in as “new” from a group buy. Go figure. Didn’t matter much to me as I was removing the aluminum star anyway and swapping out the driver as well.
Buggered threads with no lock-out is more of a problem. I wonder if something like JB Weld could be used on one side, wax applied to the other, then threaded to let it set up…thereby creating “new threads” that are insulated??? Guess that would be a gamble though, huh? My luck I’d glue it together and wreak havoc getting them back apart. lol