And you gotta know how to work them.
Could you not use old PC on switches for this?
So, from what I read here and in other threads, to use the MT-G2 with a "budget" driver, I would be best off using two Li-ion cells in series, to keep the voltage about 1v greater than the buck driver and when it goes below, it goes direct drive, but the voltage is then low enough to not hurt the LED. Is that about right?
So to keep 4S/2P it only makes sense to put in an XM-L or XM-L2 with a DrJones programmed driver, since I do not want to use spacers or dummy cells to do a 6S NiMH configuration.
I think that about sums it up?
Hmmmmm...... Rats!
Ok, so if I did break down and go 6s NiMHs, which "budget buck driver" would be the best or possibly the most reliable? I have no clue, so help me out here with some links to some.
Any of these drivers work?
http://www.lck-led.com/5000ma-driver-modes-p-935.html?cPath=135
http://intl-outdoor.com/xml-multicell-circuit-board-35a-ouput-55126v-p-543.html
http://intl-outdoor.com/xml-multicell-circuit-board-3a-55126v-p-361.html
http://kaidomain.com/product/details.S020121
O-L - you don’t need to go 6S to use a buck driver as it really won’t care what voltage the battery is as long as it’s above Vf+1V and below the specced upper limit of the driver. In fact, 8S would be better as the current draw from the battery would be slightly lower.
I know that Taskled drivers are expensive, but you do get what you pay for and there’s no “what will I get” lottery like the drivers from China.
I know, I just hate to sink $40+ into an H6Flex for a light I will want to sell once it's done. I seem to have gotten away from the "budget theme" in trying to mod different lights, but I know the H6Flex would be a good driver for the MT-G2 and 8 NiMHs in series.
The Lflex is “only” $20 and is a linear driver like a 105C but uses a momentary switch. The 6S was to possibly still use a 7135 driver with a VR chip to protect the mcu or Lflex and get the voltage up to 6V mtg territory. 8S and you’re looking at a boost driver(12V mtg) or a buck driver(6V mtg). Often for me the hardest thing to figure out is the best combination that takes into account all the limitations I’m dealing with. Only you know what those are Justin so all my suggestions are just bar napkin bs when you get down to it. It sounds like the easiest thing would be an XML, 4S2P with a DrJones driver but the mtg is still possible just harder.
I emailed George and asked him what I could use. He suggested the H6Flex with 8 NiMHs in series or the b3Flex. I’m just going off what he suggested.
yeah, the b3flex would be ideal for up to 3A, which would still be a metric ton of light and well within the capabilities of most NiMh AAs - the h6flex would be just overkill in this situation, as it’s 5A (or 6A, I can’t remember) max drive would be crazy off 1P AAs 
the H6Flex is adjustable and one setting is 3600mA, which is the one I would use. I think for the price difference, it might be fun to put 3.6 amps to it. Eneloops can take that, although probably not for a long period of time.
It may be a while though, due to the cost, but hopefully it will happen.
I used an overkill driver from I-O that would work. It’s a buck-boost, which works fine for driving the MT-G2 from 2 18650, so an 8S would work. I think there must be better drivers for the task.
I think a 4S2P config is better, which limits you to XM-L/L2 or MT-G2 with a boost driver.
This might work OK for driving an MT-G2 from 8S NiMH.
More photos in the OP.
I probably will wait till I can buy one of the Taskled drivers. The fact that they are thin makes a big difference in the limited space I have. I am concerned about room with the fatty drivers that take several mm of height space. When I can, I will buy one of George's drivers and finish the build.
That is so sweet lookin. Someone linked to another forum for me to look at. I thought you may be interested as well.
Reserved
More photos in the OP and a question about a component. Photos in the OP show the component in question.
Those are diodes, I assume to prevent a reversed battery condition from breaking things. I would not have expected it in the tailcap though…
If you replace them with bridges you will lose that function, but you may also not care depending on the driver you use.
I was wondering if that is what they are, but it did seem strange to be in the contact plate. I may just leave them if that’s the case. Since I am going to do 8 in series, I have to put in a 3rd guide pin, so that the tail cap can only go on one way, as it can be on or 180 on now. Can’t have that with 8 in series.
I think it makes sense there, as they are somewhat sizeable components due to the current and possible heat dissipation needs, as well as to provide a battery bridge. Just checked my EA4W and according to my DMM, and it’s just a straight bridge. Guess they weren’t as concerned about reverse polarity with the little guys.
KuoH
On the EA4 the circuit can be seen it's a straight thick trace, so I guess DMM check is not needed.
You are setting the bar so high OL I’m going to have to take up pole vault. Tell me you punched out the little copper round tabs and not cut them out by hand and file them to shape on the battery board?
I modded a 16mm XM-L star to use for a pcb for the smd switch, photos in the OP.
@MRsDNF - I bought the pre-cut copper rounds 3/8" diameter.
I like the use of the pcb for the smd switch. Very clever. I wonder if the stock board could be modded(sense resistor change) for more output or if the components are already maxed out.