I tested 4 on mine with my Lii-500:
- 2807
- 2850
- 2863
- 2866
close enough - also, the Lii-500 isn’t that precise, so no worries for me.
Test results, Liitokala Lii-500, 1A charge rate, 0.5A discharge rate
Battery nos. 1 thru 8.
Normal Test = Capacity measured while discharging.
Fast Test = Capacity measured during recharge cycle.
**<u>Samsung INR18650-30Q 3000mAh</u>**
Capacity #1 #2 #3 #4 Average
Normal Test 2830 2858 2869 2809 2842 mAh
Fast Test 2899 2872 2865 2863 2875 mAh
Capacity #5 #6 #7 #8 Average
Normal Test 2798 2849 2853 2865 2841 mAh
Fast Test 2858 2871 2883 2897 2877 mAh
I got about the same result on my bottom-tops but cycled them twice before testing.
4,2V cut-off on loading and 2,8V cut-off on discharging. 1A charge an 1A discharge current.
- 2875 mAh
- 2876 mAh
- 2875 mAh
Haven´t tested the others yet but the result fits very much to the results I had with the flat-tops (I kept).
Edit:
Added no.3 result. They seem kind of matched so far.
For more precise results I modded my cheap battery holder with AWG16 wire and did a spring and +contact mod for lower resistance before testing these botton-tops. Seems to work fine !
As this is thought to be a temporary solution I ordered some more professional 4-wire battery holders.
That’s very much capacity for only 0.4Volts 
I think you wanted to write 2.8V
Did a little edit …
I just ordered some of these Stainless Steel Pointed Top Cover Cap
and these Paper Insulation Gasket for Pointed these are sticky
Together with these 18650 Battery Sleeve PVC Heat Shrinkable Tube Wrap
Gonna try and make my own button tops with the 8 flat tops I have left.
The paper sticker is gonna keep the top centered and in place and the heat shrink will keep the sticker down with some extra force.
The original flat tops have an isolation ring, so even if the top would slide. It wouldn’t slide under the isolation ring. “which if it did would make a short”
Wish me luck
Updated my previous post with capacity findings. Jury is still out, more testing with different equipment required…
I ordered some magnets 4mm x 2mm. I know the 4mm is the right diameter, and I hope the 2mm will be enough to make contact in my Nitecore lights. Can’t be too large or they won’t fit into the physical polarity depression in the lights.
Decided not to hassle with trying to ship them back with all the misunderstandings going around about shipping Li-Ion cells right now. Hopefully once everyone learns what the rules are and gets comfortable with them things will improve. Right now too many are over-reacting on the side of caution to be able to rely on your shipment getting through.
I use 5mm x 2mm gold plated N52 neodym magnets and they work fine on any cell.
No surprise with me too…all Flat-tops arrive after 67 days. Packed individually and wrapped in thick foam.
I just sent BG an Email AND a PM for a win-win compromise deal.
I will test for discharge capacities when free in the coming days. Stay tuned.
my replacements came today thankyou banggood, on the charger will try them in my xpl srk tomorrow
thanks for this group buy ,everyone involved…
Sorry it took so long to post an update to this, but school has been killer, and I’ve tried to recreate what happened here.
Turns out it’s an issue with my Opus charger, the batteries are fine! Banggood didn’t ship defective cells, but they never replied to the two messages I sent them about this, so take that for what it’s worth.
For some reason, my charger seems to “reset/reboot” charging 4x Liion cells at 1A when they all reach ~3.5V. No idea why, or when this started happening. It doesn’t do it with NiMH, and it doesn’t seem to do it on lesser charge rates with Liions.
Just wanted to amend my earlier post.
good to see 
Well, BG did right by me…finally, sent me out a single 30Q button top.
Thanks, I’m relieved not so much that my cells have a bit more capacity, but that’s BG isn’t selling shoddy goods.
It is concerning that I never received a response from them. I’ve gotten fairly prompt responses from Gear Best and Fasttech about issues orders have had, historically.
BG has offered me a $30 refund for my $42 order (8pcs. 30Qs) that came in as flat-tops and therefore have no use for them as I already have several of those already…I have accepted the compromise deal, 75–25 in my favor is good enough for me.
If you live in the US I’d be willing to buy your flat tops for $25 shipped if you want to get rid of them.
Coupon is still good if anybody’s wondering. Just placed an order for six cells.
Thanks, M4D M4X
ordered 2 in Jan, they never arrived and was resent and got them last week. After charging, ran discharge
on Opus 3100 at 1A:
2872
2923
My 30Q’s shipped 03/19, received 04/09, all button tops.