My new Sky Ray King 3X arrived a few hours ago, so I installed my four of my new Keeppower 3200mAh 18650 in it, but nothing happen when I turned the King on.
Thought the King might be defective or the batteries defective
So I tested each Keeppower 18650 in a flashlight (Ultrafire XD-67) and each battery worked fine.
So spend 30 minutes trying to fully open up the King, to see it there is a lose wire I can solder into place or whatever I need to do to fix it.
Front cover (over the Cree LED) would not open, so thought I was stuck with a defective King (or at least until a replacement King ships on the slow boat from China).
Then by chance tried two of my Trustfire 18650 3200mAh (button top) in the King, and the King started working.
So I’m guessing these Keeppower flattops cannot make a good contact.
Which is a little weird as my flattop Samsung 18650 2600mAh (used laptop pulls) seem to work fine in a King.
Or am I overlooking something about using the Keeppowers in the king?
Good Day Tacoboy, 
Check the battery length, maybe your KeepPower 3200mAh 18650 flattops are just a bit too short.
Best Regards,
George
Never thought of that?
Currently the Keeppowers are being charged in my Opus, so I guess I’ll just wait a few hours, until they finish charging up, to measure them.
It looks like the plastic wrap around the keeppower might be a little too high on the battery.
I think it might be keeping the positive part on the battery from touching the positive contact ring, in the Sky Ray.
Is there away for moving that wrapping down a few millimeters?
You may have to consider putting a small solder blob on top of the cell.
I’m lazy and use very thin magnets. The resistance probably is high but the contact is made and they seem to work fine.
I’ll probably get shot down now but hey ho.
You are suggesting using magnets on top of the cells in a four cell light that you have to twist repeatedly to tighten?
…don’t put that one in your mouth either….
Bingo!! You have found the problem.
The best solution would be to purchase batteries with a button top. The quickest solution is to do as already suggested and solder a small button/blob onto the top of your batteries.
Please do some research if you decide to solder the batteries, you do not want to overheat them during soldering.
Edit: Do not remove the wrap as that could create a direct short across the top of the batteries.
Yeah okay I didn’t think about the flashlight in question. I use mine in tube lights so I don’t worry about it there. I use big topped cells in my twisty ones.
I clearly hadn’t thought about the SRK