Li-Ions should work fine… except that the tube is too short for xx650 cells. :person_facepalming:
What? 
5.35/2=2.67V
If it is 2S2P is not posible 5.35V, should be 4S1P.
5.35/4=1.34V
Not bad. Too expensive for AA flashlight ) Waiting universal power 4*AA/18650/26650.
Its a AA light. Some are looking for the “2S2P” power. Repeat it’s an AA light. Let’s see…2 cells one direction and 2 cells another direction in a single well built carrier and 5.35 volts after use. Anyone that looked at the pics should be able to tell how it holds the batteries ie. “singles”. It’s too bad many people don’t wish to speak up and say anything of actual value. This is a high quality light. Don’t be fooled by the “sales” wars. It is quite easy to draw out the condescenders. Input a questionable element of data such as cell layout and find the answer. Great job Lumintop and quality from China! …it’s called dialogue.
The driver is 0.9-6.4V. but the body is too short for Li-ion.
They could provide NW, but request MOQ of 100pcs.
Banggood just listed them : Here
NW tint need 100 pcs 
May use 18500…
Could make a extension ring and get full compatibility as the SD10.
The point being that the original SD10 was long enough. Also, the 18650 has over 3X capacity compared to 18500 and 26650 is almost double compared to 26500. So, the new design is a major step backward for run-time. I don’t know of any existing extension rings for SD4A, and have no way of making one. Lumintop should have just made their light 15mm longer (or rather they should’ve NOT made it 15mm shorter).
Edit: But thanks for keeping the conversation going. The more I talk about it, the more I realize that I don’t want this light, as much as I was looking forward to its release.
Edit 2: For those who don’t specifically require 18650/26650 compatibility, there is one point that I’ll relent on. If you have 4x AA Eneloop Pro 2450mAH cells, then you ALMOST get as much power from those as a single high-capacity 18650.
The lack of typical li-ion support is a shame, but I like the other changes they’ve done. That expensive bezel looks classy and I like the deep fins and new dual-button set-up.
Looking at this a little closer, and realizing my last Eneloop style light disappointed me, I think this might be a nice replacement for that class for me.
The SS bezel and the well built battery carrier really make it look like a high end light. Nice! Gonna have to get a better look at it later when I feel better, rough night, probably shouldn’t jump into anything at this point. 
Edit: Shouldn’t an 26500 work? Just a thought…
I love all my li-ion lights, but I value NiMh powered lights more because I can give it to anyone without worries, and even I feel safer. I would not want this light 1.5cm longer, I have enough great (better) performing lights with li-ions.
If it works with D cell (61.5mm), is only 3.5mm shorter to working with 18650
Yes, that is the problem, with xx650 battery, the tail cannot be threaded into the head. There is no spring in the tail. Only a small one in head.
Did anyone test the D-Cell-Config?
I failed using it, my SD4A will not work with it.
I prefer the original BLF SD10 far over this, because of their bad move in the design with it not being long enough for LiIon cells. ( 18650,26650,32650) I have a TF 32650 in my SD10, and its run times are phenomenal.
+1 They’re moving backward.
Previous one have wide range voltage as advantage, but may be lack of effort to improved and perfect it, perhaps they under estimate that advantage as selling point.
+1 here as well. Love the 32650 in my modded SD10, with a yellow LED behind the switch. I took a TF 32650 and stripped off the protection circuit, and wow, the unprotected cell they use is low resistance, high performer. Was look'n forward to the styling changes and two e-switch buttons, but if a 26650 or 32650 can't fit, it's NG.
The EFEST 26500 cell would make it usable if it fits, but at 3000 mAh, it's down a bit from the 26650 and 32650's.
+1
The answer to this question is fundamental to make a decision.