So could you feasibly take a fatty triple XM-L like the Ultrafire T70 that isn't quite "turbo" driven like the DRY and operate it with a 26650 or 32600? It seems it would fall within the comfortable max draw of 2C, assuming the cell has ~4000ma capacity and the driver is drawing less than 8A, which is supposed to be the case with the T70. Couldn't this work?
The capacity takes a hit, but I'm focused on the simplicity and safety of operating off a single cell.
As long as the 186650 cells are to be operated in parallel and it fits (even if somewhat), it is ok.
The UF-T70 does not take parallel cells, it is in series.
The Sky Ray King is parallel. It should fit a 32650.
I have used both 32600 (with spacer) and 26650 in my XTAR S1, but for testing only. The hit in capacity is quite a lot.
hmm, wonder if you could find one of those lipo RC packs size relatively close - they're safe...no?
need a balance charger though
So why is there a difference between parallel and series? Does the driver know the difference if it's just one cell? I figured one cell completes the series if the battery carrier is set up that way. And how much of a hit to capacity are we talking about?
Batteries in series adds up in voltage. 2 x 18650s (4.2V charged) will yield 8.4V
Batteries in parallel will double the capacity (mAh) 2 x 18650s (2600 mAh) will yield 5200 mAh
The driver will have a certain input voltage range that will allow it to work.
Parallel - multiplies the amperage, but the voltage remains the same.
Series multiplies the voltage, but the amperage remains the same.
If the batteries are in series already, then the driver expects to see twice the voltage of a single cell. Depending on the driver, it may or may not work with one cell (half the expected voltage) and if it does, it should have quite a reduction in output.
D'oh! I suppose I already knew that but I think I must be in the mindset of having a wider voltage range. These fatty triple XM-L's in series would most likely always start with a higher voltage so parallel would be required unless the driver is swapped.
I wonder if it's even worth it since you obviously won't get the output these multiple XM-L lights are designed for. I don't have an understanding of the voltage XM-L emitters accept and how much more output you can get from a single cell with high capacity powering 3 emitters versus 1.
You can't drive multiple XMLs to the max on a single cell because resistance plays a much bigger part of the of determining output at 3.x volts vs 10.x volts. It is not possible to match something like the DRY with a single 26650. Now if you want a more reasonable level of output, that's doable, but still requires more of the host than if the LEDs were in series.
Its something I would like too, its just not that easy.
So what's up with the Elektro Lumens Big Bruiser? One user measured 2400 OTF lumens. It operates on one 26650.
By the way, that's a sweet looking light.
Is anyone familiar with the Elektro Lumens Big Bruiser and why it's successful at powering 3 x XM-L at 2400 OTF lumens from a single 26650?
I'd bet the DRY is still brighter. Notice that it is a twisty. Typical clickies aren't going be able to handle the amperage necessary. They add resistance which will drop the voltage available to the LEDs (and at 10A aren't going to last long). That host was built for a single 26650 with resistance in mind.
The BB is Direct Drive. The brightness falls in step with the battery voltage.
I used the same MPCB + optic in my CNQG longrun triple conversion. With 3 cells, almost 3k OTF is possible.
And your custom triple is awesome! I was jealous when you showed it off and now I'm still jealous but I think I want it to operate on a 26650 or 32650 
haha
The Big Bruiser is just one mode, correct? I read comments of it being a "one trick pony," but not negatively speaking.
I'm just starting to feel a little less comfortable leaving the DRY with my dad. He's no dummy and he's quite crafty, but he just doesn't have enough interest to monitor the batteries in his flashlights. This is what inspired me to think about operating these type of lights on a single, larger battery. I'm not giving up yet!
Thanks for the kind words.
Have you considered the 4/7s X10 ? At the current sales prices (just under $70, shipped) they are worth a look.
Thermal management and low-voltage cutoff makes the inevitable LED swap worth it, IMO.
I'm really digging the 1.5 hour runtime on HI on a single cell, too. When you get bored, there's enough room to mod it with the triple XM-L setup...
C'mon.. all you need to do is build me one of your CQG triple's powered by a 26550
I actually like the X10 but I'm not simply looking for a 26650 light. I was specifically pondering the concept of powering a triple with a 26650 cell for safety reasons. Something along the lines of the Big Bruiser but not having to be so custom. I was specifically curious about retrofitting a current light. Powering the SkyRay King with a 26650 seems to be all around counterproductive since you're lowering capacity and parallel is already a safer means of operation, correct?
Correct.
How about a JM07-style light with the same light engine as the CNQG custom ?
On the left is the single-26650 light, on the right is the Ultrafire MCU-C88 without reflector.
Now THAT we could do. With modes.
Thats what Iām doing. I have the triple and the optics. I just have to figure out a heatsink and put together a driver. I"m only shooting for about 5A though.
If it is typical of most of Wayne's designs, it is direct drive.
Yes, I believe it's simply single mode direct drive. May I burden you or someone else to educate me on why direct drive makes a difference concerning battery operation (i.e. 26650 vs 3 x 18650)? I'm trying to understand the differences in operating these heavily driven lights in regards to how many cells are used.
Direct drive is just that - an LED, directly connected to the cell.
There are no driver losses, since there is no driver. :)
Brightness is a function of battery voltage; as voltage drops, so does lux.