Not button top ?
There is a white plastic washer to prevent reverse battery insertion, a 30Q flat top will or will not touch the positive of the battery carrier depending of its plastic wrapper. Sometimes it can be pushed enough for the flat top to make contact, sometines not. Not sure, can’t test it with my 30Q flat top, my MF-01 didn’t arrive yet.
The original MT-18 does not have those rings. They were added to the MF-18 after being recommended by pre-production reviewers, to lessen the chance that newbies could accidentally trash their light. You can pop them off (carefully) with a flat head screwdriver or knife.
The reviewer in this vid did just that with his MF-01, and his flat tops fit just fine.
We’re they button top or flat top? If flat, did you add solder blobs?
I find that the flood your talking about is only there at the higher output levels. How was the flood at 600 and 1500 lumen when walking at night?
How can you say this when you haven’t measured the voltage?
I am using Button top batteries.I just tried again and it only ran on 2 batteries.I was careful to position them correctly.
It is hard to run this light on the lower settings because the high ones are so impressive. This light stops coons in their tracks.
Do you have a DMM? I would check which cells are not making contact and see if the button top is taller than the white disc.
Install 2 cells in series and see if you get 8 volts, then put those same 2 cells in the other 2 battery carrier slots. See if it’s making 8 volts. There might be something on the battery carrier that’s not making contact.
Make sure the 8 screws on the carrier are tight.
I took the white discs out and all is great now.Two of the discs were higher than the others and one contact needed to be solder.The disk was sitting loose on it.So when the disk came off the contact came also. The button tops were not making contact. They do now.Thanks for the help.It gets hot faster now.
I’m glad you got it fixed.
Did you have full turbo with only the 2 cells working? That’s impressive from those 30Q.
Hallo
Does that mean I will have a problem with the turbo, I ordered Sanyo 18650GA?
I first bypasses all the 5 stock springs and put those white washers away & with Sony VTC6s this thing easily puts out the 12k cree lumen on turbo!!
But battery drain on “playmodus” seems high - ergo no economic light on the higher modes! 
…
What do you mean? Are you thinking they are not good enough batteries? Those are plenty powerful.
http://lygte-info.dk/review/batteries2012/Common18650comparator.php
Comparing with Samsung 18650 30Q, you can see the voltage drop at 10 amper more .How do they handle if they are half empty, with turbo or high mode.
I really don’t know. You would probably get less time on turbo compared to the 30Q, but gain more run time at the lower output levels.
Maybe someone with first hand knowledge can answer that question.
The most amperage any one cell will see is about 8 amps in case anyone was wondering.
received mine yesterday. ASTROLUX MF-01 seems like having higher QC than mateminco mt18; I can not find any MT18’s issues on MF-01.
I’m able use both button top (30Q) & flat top (VTC5/6, Sanyo GA) without removing the white plastic protective rings in battery carrier.
Size comparison- DQG 26650, MK34vn, m43, haikelite sc02, MF-01, x7
(WB set 5000k) S41s-219B 5000K VS. S42-219C 5000K VS. MF-01-219C 5000K
(WB set 5000k) M43- 219C D320 5000K VS. S41-219C 90+ CRI 4000K VS. MF-01-219C 5000K
(WB set 5000k) S41s XPG3 6500K VS. MF-01 219C 5000K
I measured the voltage of the cells afterwards, and they had 4.06V each. If the red light comes on at 3.4V, that’s a difference of 0.66V.
Sorry, but that method is not accurate. You have to measure the cells when they are under load. Once you remove the load the cell voltage will jump back up.
It’s just like with the cranking car. When the engine is cranking over the lights get dimmer. Then when you stop cranking (no start up) they go back up in brightness.
Yeah 
What a big chunk of metal! Thanks Freeme 
Noctigon M43 Meteor vs Astrolux MF-01 (with Stainless Steel Bezel)
(Meteor with 4xHG2 Button Top)
(MF-01 with 4x30Q Button Top)
Ceiling Bound: Meteor (S4-old type) - 604 lux; MF-01 (219C) - 912 lux
I think you misunderstood me. As I mentioned, I wasn’t able to measure the voltage sag while the light was running, only the resting voltage of the batteries. With that being 4.06V, the red light came on after about ten seconds. I don’t know whether the voltage actually dropped that far under load, or whether the warning light kicked in earlier than it was supposed to. That’s why I’m hoping that someone else who owns the light can say whether they observed the same behaviour, and possibly take some measurements under load.
I understood you. Right now your just kinda guessing what’s going on. The only way to know for sure is to get a helper to hold the volt meter leads while you push the battery carrier in and turn on the light. Then you will know for sure what’s going on with your particular light and your battery combination.
Yes, that’s what I mean - until I’ve got a second pair of hands available, or someone else has observed the same with their light and can measure what is going on, it’s all guesswork.
I’m surprised that there haven’t been more reports about the light, since I assume that a number of people must have received theirs by now.