I just recently replaced the driver in my sst-50. I swapped it out for a 1.5 amp, 4 mode (moon,2%,33%,100%) constant current driver. The light originally had a 2.8 amp driver but I was more interested in keeping the lower modes low. The high output is still impressive for only being pushed at 1.5 amps.
This can be done without removing the reflector, which is a pita, by removing and disconnecting the wires from the driver. As you can see additional modules can be added to the driver to bring it up to 3 amps.
Badtziscool is right, the SST-50's were reflowed directly to the pill.
As for the hum, it is called inductor whine and can be fixed by reprogramming the levels to different frequencies. FWIW, most lights have this high frequency whine on one at least one mode. My Oveready Triple, Surefire V2 Vampire, and SOYCD Tri-EDC all have different frequency whines if you listen closely. Other lights I've own did so as well.
You could get the driver swapped or reprogrammed...its not any different from working on a Tri-EDC. Or....you can find someone to machine a pill...then adding the LED, MPCB, and driver should be something most modders can do. The threading for the pill should be 7/8-28 UN.
My .02 would be to keep the SST-50 engine and just upgrade the driver. Here's why, I know that the SST-50 seems like old technology, but the it is actually a very powerful emitter. Right now, it's only being driven at either 1.2A or 2.8A. However, it is capable of up to 5A of current and a maximum of 3.9 forward volts. For reference, that is 19.5W of power!!! Max junction temp is also pretty good, 150C. But here is the real kicker, these suckers were designed to put out over 1,150 lumens at max drive levels. Of course, OTF lumens will be less depending on thermal management, optics, driver efficiency, etc...
What does that mean for you? It means you have a beast just waiting to be unleashed. It means that the LED is bonded to the heatsink for very good heat dissipation. It means, with minimal effort, the driver can be swapped for something much more powerful and with the option for custom firmware and user programming. Sure, an XM-L2 may have better efficiency per watt at a much lower drive current. But if you give this baby enough juice, it can hold it's own quite nicely. Even though you're limited to an IMR 16340, you can still run it at ~4A and see a significant boost in output.
If I am mistaken about any of the data above, please correct me.
Here's the data sheet from Luminus
As far as batteries go, your best options are AW IMR16340 (red), Efest IMR16340 V2 (red), or AWT IMR16340 (yellow). AW is considered the gold standard for IMR cells but both the Efest and AWT look like they outperform the AW 16340's.
The 700mAh were only rated up to 6A and that's just the safety rating. Useful capacity at that current is very low. Please see this thread https://www.candlepowerforums.com/threads/392163
I'd recommend the new 800mAh AW IMR18350's for that application, if you want to use AW's.
Not sure about the 5mA. Did you check the data sheet? Might be in there somewhere...dunno.
You are correct, capacity is an issue. Is AW selling the new 800mAh on the marketplace?
Yup, dealers have had them for a while too as well. The big difference is the 12A discharge rate. Haven't seen curves yet but they should be better at handling increased load.
The list of Canadian dealers
Mine runs fine at 5 ma, the problem others may be having could be from a poor ground. The driver can act erratic or not function properly.
From my understanding it does use a single chip for moonlight rather than a percentage of the total drive circuit. So moonlight never worked? Have you contacted M.E. about this issue? Hopefully they could test it and correct the issue.