I have a Manker BLF A6 using a Panasonic NCR18650B battery. I think the batt gives out around 7 amps. What’s the benefits for getting batteries that output 20-30 amps? What’s a good button top 18650 to get?
Cheers
I like using Samsung 30Q’s, Sony VTC6’s and LG HG2’s in most lights. Those will do you just fine in all but the most thirsty of lights. All about the same current and capacity. As long as they are bought from reputable sellers you can’t really go wrong. Illumn, IMR, or Liion. Not sure of the best place in Canada to get them though.
The NCR18650B will not give you the highest lumens as at a higher current the voltage will sag. Higher amp batteries like the Samusng INR18650-30Q will give more lumens and runtime on the brighter levels than your Pany B.
The BLF A6 has a FET driver which needs high voltage at the amps it’s being driven at. If there’s too much voltage sag the lumens will be less.
I’m not sure you’ll notice much of a difference, if any unless you have two side by side. It’ll definitely get hotter though
You can’t go by the rating on the battery. Since these flashlights depend on high voltage, the Pany B with have too much voltage sag at 7 Amps and much lower. The Pany B is good for flashlights up to say 8-900 lumens
None. 
By design cylindrical batteries are flat tops, being the geometric shape of its anode or top pole an identifying trait of their original manufacturer. Button tops are added by third party manufacturers to meet the demand of certain customers, and in doing so the third party may spuriously rewrap a different, more accessible and of course cheap cell; the button top may also be attached shoddily, resulting in an increase in cell internal resistance. Always buy from really reputable sellers if getting button tops (Banggood isn't one of them, don't buy Samsung 30Q button tops there).
All of my flat top 30Qs from banggood have been genuine but I do recall a button top photo that looked suspect.
I think all added button tops increase resistance even if it’s done well.
I have button top 30Qs that were spot welded very well and there’s a 0.07v discharge difference to flat tops.
Get a button top Samsung INR18650-30Q or if you’re after a little more runtime get the Sanyo NCR18650GA flat top. The GA’s positive end is slightly risen which acts as a button top
Great info from everyone. Now the hard part…which one? 
I was wondering where most of the members order batteries online from? I usually go to Ebay.ca or Amazon.ca. I heard about Alliexpress also. There’re pretty much the same I think.
I’ve had 3 button-tops go bad, all from Banggood. I think they were genuine 30Q cells underneath, but I suspect they are low-grade cells. They developed very high self-discharge, and would go flat within a few days if left by themselves.
The flat-tops I’ve bought from Banggood have all performed well, and are still going strong. So, I think the problem is whoever is supplying them with the button-top mods.
No, no, no!!! Stay away from those places. I’ve had success from one Ali shop, but that was a couple of years ago and I think they’re all selling fakes now.
I get mine from Illumn in the US. There are a couple of other good on-line shops there, too. I haven’t tried 18650Canada.com, but I’ve heard they sell genuine cells if you live in Canada (they might ship outside, though I’m not sure if the shipping would be expensive).
I got all my 30Qs from Fasttech, BTs for my Q8s and FTs for everything else, and never had a problem. They all clocked in right around 3000mAH. Can’t really check internal resistance reliably, as values are all over the place even just retrying the same “quick test” in succession without touching anything else.
Just get the Samsung INR18650-30Q flat top, you can’t go wrong.
Lucky Electronics Store is among the trusted AliExpress stores. There’s a list on BLF somewhere.
That’s my supplier above and have purchased over 2000 cells which have been all genuine. I’ve bought Samsung 30Q, LG MJ1, Panasonic B, Sanyo GA, Keeppower etc. Tested thoroughly with my computerized battery analyzer and resistance tester.
This store will also add a button top for a few cents extra. Just ask for a listing of 1 or 2 30Q’s since the smallest quantity available currently is 4pcs
Go to a vape shop if u need a single bat
Its cheaper after taxes n shipping in canuckistan 
After all the good info from everyone, I think I’ll try the Samsung INR18650-30Q flat top.
I think I’ll try to solder the ball onto the flattop as some members seem to be doing. I fiddle around with electronics(Arduino stuff) so I’m not bad at soldering. Just hope the solder ball sticks.
I use this cell for my white 1 builds. With this cell and a few other combinations, I get 4.5A on turbo. Cell usage varies by application.
This guy is really good; I’ve bought from him and his prices and products are as good as you’ll find.
Hank33 - I am also in B.C. and have recently ordered twice from 18650Canada.com. I am a satisfied customer only. You may wish to take a look as he is located in Canada and the prices and shipping (considering it’s Canada post) are fair. He is quite quick also.
John.
https://therestaurantboss.com/do-or-do-not-there-is-no-try-yoda/
Without proper flux soldering to steel can be a bitch. With it, it's a piece of cake:
This: https://www.aliexpress.com/item/32900951283.html 
If soldering with standard Sn63Pb37 solder lay a full drop of flux (no need to mess with the finger), and be adviced to use a big, hot and heavily wet soldering tip for maximum heat transfer speed. Once the solder is laid remove the tip quickly and soon afterwards dip the cell top a bit into a small cup or tumbler with denatured or isopropyl alcohol to clean any flux remainings. Leave the cell pointing downwards while the alcohol dries out or it'll mess with the wrap inscriptions.
Mon, 11/25/2019 - 22:53
The blf a6 takes flattops, not need for a button
I just use rosin core solder, and it works. Ugly and messy, but the solder sticks fine. That method in the video does look much nicer and easier, though!
It can stick on unblemished cells because the steel of the can has a nickel coating. Once that is gone your soldering chances without proper flux are gone too. The above flux makes short work of rust remainings, but if you use it to remove rust better clean the flux and apply oil over the metal just afterwards or it won't last.