The 12V XHP-70 emitter is the same emitter as the 6V XHP-70, it’s just wired up differently on the mcpcb. There are options in mcpcb footprint to allow this. No real gain in going to 12V unless you’re not going to be using it in a flashlight.
what do you mean there is no gain? I want a bigger and longer running flashlight 
Won’t be any longer running, 5A 6V is the same as 2.5A 12V, as far as the cells are concerned it all works out the same… but of course you’ll have to use more cells and probably have to use a Buck driver.
If you want bigger and longer running maybe the showerhead style Trustfire TR-J20 would fill the bill. 12 of the XM-L emitters run off of 3 big fat 32650’s. Plenty big, for sure!
Changing the L6 to an XHP-35 which is 12V and using an extension for 4 cells would give you the bigger light, more throw.
Lol
Using the L6 now (passed where it was and grabbed it ;))
Today no heavy thorny plants battling so an intact hand for a change.
The knurling I deemed way too aggressive is actually nice with 100% intact hand palms.
The squirrels don’t know what to make of this wall of light (and that reminds me to check the hazelnut trees NOW to see if something is there for us 
)
So yeah before I had just too much little wounds on my hands to appreciate the L6 now that my hands are nice and lady like my appreciation of the L6 has risen higher!
(BTW all that talk about series voltage and such confused me it was so simple (parallel more mAh for each cell and series more voltage for each cell, dangit you know it alls make it not much easier 
)
That is exactly what I want to see with the smooth reflector but I don’t know that I see Simon doing it as there are no protected 26350 cells. We might be looking at modded lights only with that configuration (for now) and you can bet I’ll be begging someone to build one for me!
Once I see a proper L6 XHP35-HI build if the reflector proves s a good fit for that emitter I will entertain another design I have in mind.
One step at a time Buddy!
Get well and let us enjoy this beast. Smooth reflector, smaller tubes all when the time is ripe, I is awesome as it is!
(And in case any1 is wondering, no hazelnuts for us (yet)
I would love to see a truly massive head light with a DO1 style setup, something in the 90mm range with an XHP35 (or even a xhp50/70) running 4 cells in series al la skyray king / TM16.
Or something like the TM16 with 4x XHP35 would be epic, very different but epic none the less. Could possibly hit 10k lumens in modded form.
You could even make the same host and then just offer different reflectors for a large single or a quad setup in the same head. Save a lot on production costs and offer a lot of options for reduces start up costs.
Come to think of it, wasn’t ol lumens talking about wanting to make something along these lines?
The XHP-35 won’t make the output of an XHP-70, not anywhere close. And in a massive light, I’ve “only” seen the XHP-70 make 6400 lumens. (Olight SR-90 Intimidator with Illuminations Machines Lum5-90 reflector)
I’d be looking more for high throw numbers in an XHP35-HI build. I realize it will have nowhere near the lumen numbers of the 70 and I care not.
330Kcd in the Shooter 2X with some 2200 lumens, this at 2.89A from a modified LD-2 driver powered by 4 18650’s.
I like my lights small and light and the Manker U21 with the XHP-35Hi fills my need for this LED.
I do have the Convoy L6 on order for its specific output and run time length.
OK, I swear no long post like last night!
I thought I understood voltage and current in series and parallel circuits, but this bothers me…
If I have a 1000mah cell with a 100ma draw the battery will be good for 10 hours assuming 100% efficiency. If I put another 1000mah battery in series the mah stays the same, and if the draw is the same my runtime stays the same? That can’t be; it offends logic and common sense. If it was, there would be no reason for 2 cell lights. Please tell me that logic and common sense agree and that (excluding inefficiencies) the runtime is doubled. If not, I’m definitely removing the extension from the L2 and going with one battery. I’ve been assuming that the driver is converting voltage into current, however it does it, yes/no? (Something like my PV solar battery charger, where I send the juice down at 80+ volts to make use of smaller cable, but the charger converts that to lower voltage and higher current that the batteries can use. ) If I think of it as total wattage available all of a sudden it makes sense. Does that make sense?
To figure runtimes I’ve been dividing mah of the battery by the current draw to get runtime in hours. That’s correct, yes? (excluding inefficiency) But if the light can take 2 cells in series I’ve been doubling the runtime. Correct? Of course the battery mah could also be doubled for the same result.
Or am I all wet? Please try to keep the discussion in laymans terms for me.
Thanks!
You aren’t including voltage in your considerations. Let’s take a hypothetical cell where the voltage stays the same during the entire discharge so you don’t worry about 100 other variables.
One 3.7v cell drawing 100mah will output .37 watts. If you put another cell in series and still draw 100mah you will be outputting .74 watts.
So with the same current draw and same run time you will get twice the power.
Of course the real world has more variables and nothing is 100% efficient but you starting with the fewest number of variables is the best way to learn. Add more variables later.
2 cells in series keep the mAh capacity as listed on the cell, but double the available voltage. If you don’t have a buck driver converting the 8.4V back down to the 3.5-3.7Vf of the 3V emitter you’re gonna blow the emitter with too much voltage.
Current is the amperage the emitter pulls from the cell. The only way you’re going to get 100mA draw is if you limit it with a driver or a resistance. With a resistor holding current down to 100mA draw, yes, the 1000mAh cell should do around 10 hours run time, more or less (due to the cell losing charge rate in a non-linear fashion)
When you put 2 cells in series and double the voltage you can’t feed the same emitter as a single cell, as it turns out our Li-ion cells are close enough to the required forward voltage of the emitter that they can run in direct drive. But 2 cells are way over the normal 3V emitter’s abilities and will fry it in a nano-second.
Conversely, if we use a 6V emitter like the XHP-50 or XHP-70 then a single cell can’t give the required operating voltage. So the 2 cells at 8.4V do the job, with enough overhead to overclock the emitter and let it do some 7.3Vf at a high amperage rate, producing a lot of heat in the process. So if we want to limit the overclocking we need to control the amperage, which in turn will keep forward voltage down and heat at a specific controlled point as well. In the case of the L6, I stacked an R140 resistor on top of the 2 R182 already present for an amperage of 6.36A and a lumens output of 4600 or so. More current will produce more heat, which will adversely affect the L6’s ability to maintain temperature and allow a rapid drop in output due to overheating of the emitter. This is because the 8.4V of the 2 cells is close to the maximum forward voltage the 6V emitter is capable of. The differences here are due to the 6V emitter and it’s higher capabilities.
So as you see, it’s not a gain of capacity from stacking the 2 cells in a light requiring a 3V supply (as in XM-L2, XP-L, XP-G2) it’s the halving of the voltage by the driver (Buck driver) that allows a corresponding reduction in amperage draw, which gives that apparent doubling of run time.
A few rare lights have the ability to run one cell or two cells to the same 3V emitter, and this is what’s causing the confusion. When fed 2 cells this driver goes into Buck drive with constant current, halving the voltage to the emitter so it doesn’t blow. These types of drivers are usually only around 86% efficient, making heat in the conversion process to eliminate the excess voltage. So there isn’t a doubling effect due to the heat losses. This kind of driver is what’s causing the confusion, no doubt.
Layman’s terms are all I know, I’m not an electrical engineer by any means and only know what I do know about it from building some 300-400 flashlights. I may not be explaining it well as I don’t have all that book sense other’s here have. I do know what works though, and have managed to build some pretty intense flashlights. I’ve managed to blow my share of emitters in the process.
makes no sense to me, L6 already uses buck driver (6V LED, 8.4V from 2 cells), if we throw 4 cells tube and 12V XHP70 together we will get 16.8V from batteries, so buck driver will work fine and we will get roughly 2x work time.
Forget about the driver first. The LED requires a specific wattage for any given level of output. Wattage is the product of voltage and current (V x A). For the same output, and therefore requiring the same wattage, if you double the voltage, the required current is halved. So, simply put, if you have 2 cells in series, the current required to produce the same output is halved, and as a result, runtime is doubled. Of course, in real life, because of nonlinearity and losses, runtime is less than doubled.
In the case of 2 cells in series with a buck driver, think of the buck driver as a voltage-amp combination converter: it takes one combination of V and A from the cells and converts it to another combination of V and A to feed the LED.
An example. A LED requires 16 watts to produce X lumens.
Its minimum forward voltage at 16 watts is 4V.
Say one cell can provide 4V, so with only one cell, it needs to provide 4A to drive the LED at 16 watts to produce X lumens.
With 2 cells in series, the total voltage increases to 8V, so now both cells need to provide only 2A each to drive the LED at 16 watts to produce X lumens.
The buck driver takes the 8V-2A combination from the cells and converts it into the 4V-4A combination to drive the LED.
2A is what you’d get measuring current at the tailcap, and 4A is what you’d get measureing across the LED.
Can we just make a separate topic for battery series or parallel or electronic basics discussion?
Given the confusion this sounds like a plan!
BrianK, first don’t apologize to the dumbed-down smart-phoney/phony-smart crowd who have never read more than 4 paragraphs in a row, much less a book. It’s okay to put peer pressure on people to be smarter, but when I see peer pressure being put on others to be DUMBER, that makes me snap. Your anecdotes of rural living have been the most interesting and entertaining things I’ve read all day, and on-topic enough as it did deal with the dark and why we need these lights. It was rude for someone to call attention to “how much you’ve written” with literally nothing else to add, just empty thoughtlessness, and no… them putting a smiley face after it did not stop it from making it rude or stupid. I get the mental image of cave men who’ve never seen a wheeled vehicle before. You deal with it pleasantly, but I don’t feel indulging a suicidal culture of racing to see who can be the stupidest, most unread person is good for humanity. I’ve actually had a jerk PM me before asking me to ‘write less’, as if he had no choice but to read every word I wrote. Just seeing “wow look at all those word thingies!” is apparently enough to break some people’s minds. They’ll read 64 pages of thread text, but only as long as each post goes no further than a few sentences. Even if the net amount of words are the same, it has to be broken up into little easy chunks, which is actually quite a good analogy for Voltage and Wattage, which I’ll segway into.
Apologies if this has come up already, I usually read an entire thread before ever commenting, but I’ll use the water analogy, even though electricity doesn’t really behave like water. But for understanding voltage, current, and wattage, it works well enough.
You’re standing beside a stream out there in Maine.
How much water is flowing by you?
Well, that’s a product of both the girth of the stream, and the speed the water is flowing.
Wide stream but ‘slow flow’ can amount to the same amount of water as a narrower stream that’s flowing fast. Same amount of water. But the speed of the water is voltage. Width of the stream is current. TOTAL AMOUNT OF WATER = WATTAGE.
So wattage really is the amount of actual energy going through.
Wattage doesn’t care about volts or current. It’s just total energy.
That’s why watt-hours IS a better way to rate battery capacity, especially of things like laptop batteries, which come in a variety of voltages.
This is the only electric equation I have memorized, but I use it all the time, we know this now:
Volts x Current [by current, I mean Amps] = Watts.
4-volt battery running at 1 amp = putting out 4 watts.
1-volt battery running at 4 amps = putting out 4 watts.
^ The 4-volt battery running at 1 amp, will be having an easier time of it, yes?
The other maxim which works in physics, and in life: Energy always flows from high to low.
So when you have that small stream, but it’s flowing fast, that’s because it has a good downhill drop (head, I think it’s called). Like would be needed for an old water-powered sawmill. Or you’re shooting a tremendous amount of water through a straw or something. High voltage, but low current. Like the little 12V alkaline battery in a garage door remote. Pretty high voltage for such a little battery, but it can’t put out a lot of total wattage, due to its size. (Interesting note on 9V and 12 alkaline batteries: they are actually 6- and 8-cell mini batteries, themselves in series.)
The opposite would be like a big alkaline 1.5-volt D cell. Low voltage, but can put out a decent current.
Well, it’s harder to build a water wheel with a lot of water that doesn’t have far to drop and isn’t flowing very fast. It helps to have both, but you need that drop (voltage).
So as things flow from high to low to get things done, it’s easier to start with a higher voltage, and let it drop, than to try to artificially make the voltage higher, so it can still drop later on. Every stage introduces extra inefficiency and complexity. And boosting voltage (boost circuit) is not as easy or efficient. It sucks. But it is that way.
So, batteries don’t like to produce a lot of current, apparently. But then again, introducing a lot of cells makes its own complexity. So, it’s a balance.
Single-cell lights take advantage of the fact that many LEDs need a voltage of less than ~3 volts to run them. So, a simple Lithium cell works well, and keeps it simple. Energy flows from high to low, so you’ve got to have your power source of a higher voltage than what it’s dumping into. It’s like water flowing downhill. Water is not going to flow uphill. So a 4V li-ion cell won’t light up an LED which needs 6V or 12V to run. You have to be higher. It’s like gravity, kind of.
These higher-power Crees are made to need 6 volts or even 12. So let’s say 6. So yeah, you need to feed that LED a voltage higher than that (within their specified ideal range for the LED). Two li-ion cells in series (about 8 volts) will do that. But just using ONE CELL that’s TWICE AS BIG as one of the previous two cells (same amount of “batteriage”), well it’s only producing 4V, so it’s never gonna light up that 6V LED. Trying to get 7 or more volts out of a 4-volt cell is kind of like trying to make water run uphill. In electricity, you can do it, but you will have to cannibalize some of that energy that makes the water wheel run, to run a pump that sends some water higher than the stream already is, so that bit of water can run down fast with that bigger drop it now has. That new compact, single-cell XHP35 (which needs 12V) is rare beast, but perhaps a harbinger of things to come. The main unusual thing about the light is that major boost circuit.
So, to close, if you have two cells in series, or just one cell that’s overall the same amount of actual battery material, they will in the end put out the same amount of total energy (watts), but you just want the volts to be in a range that’s at or a little above whatever the LED needs to run. Being below that threshold calls for less-common, less-cheap, more-fancy circuitry.
But having much higher voltage for no reason is not good either. I’ve seen plenty of LED flashlights that use two 18650’s in series, even though the LED is perfectly capable of being powered by less than 4 volts (one li-ion cell). They then have to use a buck circuit to get those 8 volts down to 3.x volts or whatever. To me, that’s really dumb (and inefficient) too. The reason they do this (my understanding) is because metal is cheap to buy in tubes. And if they want to make a flashlight with more runtime (two 18650’s, for example), it’s cheaper for them to slide two 18650s down a tube (lining up in series, which has the consequence of doubling the voltage, not just runtime), than to figure out a way to make the cells line up side-by-side to they can be easily wired Parallel to each other.
I have a policy of NOT buying a light that uses multiple cells in Series, unless there is an actual voltage need for those multiple cells. First, I don’t like long or big flashlight bodies! But really, running lithium in series is much less-safe than just a single cell. When running in series, those multiple cells basically act as one… but they are not one. They are different, and if one cell starts to have a problem, the consequences can much more quickly take a bad turn than when it’s just one cell crapping out.
I too liked the Small Sun ZY-T08 (dual-cell but parallel, side-by-side), but missed out on getting a properly-modded one from MtnElectronics when available. Other manufacturers could take a cue from that type of side-by-side body strategy for either parallel or series. (And well, I guess that model is “inspired by Fenix” TK series, so I suppose some mfr’s DID take notice.)
And at some point, the higher you raise the voltage at all (regardless of how many cells), the less-safe things become when you’re dealing with significant amounts of electricity. At some point, it’s like those jets of water that can be used as ‘knives’. At some point, you don’t need much water at all, to do some damage, if that small stream of water is flowing fast enough (has enough pressure behind it—that’s Voltage), like a laser of water. For me, this mark seems to be over somewhere around 50 or 60 volts, especially with larger power supplies. We’re not really there with LEDs yet. But it is coming, with electric vehicles.
If there’s something outstanding you think I might be able to elucidate, please let me know.
I’d also like to stick up for powerful lights with small batteries, even at the cost of runtime.
I’ve never understood why some people think that EVERYONE who wants a powerful light, wants to be able to go hours in the ‘highest high’. I mean, do drag-race cars drive cross-crountry? How big is the gas tank in a drag racer? I actually think most people use very high modes for NOT very long. Most of us are smart enough (or need to use) lower modes most of the time. Two 26350s can power lower modes for quite a long time. But heck, my CR2-sized li-ion Quark xp-g keychain light only gets charged ONCE per year! And still not necessary at that point! That little light will go about as bright as any decent xp-g flashlight. Sure, not as long, but i HAVE it, it’s on my keychain! And y’know what? I don’t NEED it to be in highest mode but for a few seconds, when I do! Same goes for me with a bigger light. Indoors, super-bright is mainly useless. Outside, if I need to go max, it’s usually for only a few SECONDS. But if I need it, I need it! I’m not going for hours-long walks in the dark. I’m going out to check something out. I want to see what it is, and I won’t be long. But I need to SEE what it is! If I’m doing a car repair, I’ll use a trouble light. If a light is too physically big, I’ll be less likely to grab it or take it some place.
…I’d like to see what a Smooth reflector would look like. I hate Orange Peel, though its usage here actually serves a function. My first ‘powerful’ LED light was a Seoul P4, and the cross was admittedly distracting. (Then again, so was losing effective distance.)
Thanks gents! BR’ that explanation was particularly valuable. Thanks for taking the time to write it. I pretty much had it, but as Static wrote, I wasn’t including voltage in my considerations. That’s why when I took wattage into account it made sense and not until. I wasn’t working a formula for that, it was just a mental exercise in logic. It’s the same way my PV system works (basically) I send power down at 80+ volts and lower amperage, then after if comes in it is converted to voltage that the batteries can use for charging with a stepped up amperage. Not figuring for losses, everything balances out and wattage is wattage, just different ways to achieve it. In a light the LED takes the place of the batteries in my PV system. There may be more differences, but I’m simplifying.
BR, you made up my mind about trying to add a 3rd cell to the L6. #1 it would serve no purpose, and it would add additional potential problems. So why do it? But now with my newly figured runtimes there is no need anyway. So it would be a solution in search of a problem, while potentially causing some.
BTW, That discussion in answer to my question should be stickied. The problem for noobs is that we don’t know what to ask. That explanation answered lots of things I didn’t know to ask.
Thanks again gents!