Someone who has cells from the original batch and from the “probably fake” should test them in the same charger with the same parameters, its the only way to know for sure.
I thought/think this is correct also.
Just an fyi, The LK's are a little wider than most, maybe all 26650's and barely fit in the new Lumintop SD26. Some get a little stuck, some don't do too bad. I have the SD26 fully modded with a TA triple driver and the new NarsilTriple v1.3 running a XPL2 V6 3B, getting 8.6A (on an EFEST) out of it and 2,000 lumens.
I have 2 separate batch's of LK 50A's I bought, first original batch from 08/2016 GearBest and a 2nd batch from 12/2016 BangGood, slightly lower capacity, with the "F3" marker as shown above. What I think I'm seeing is variations between batch's, nothing more, but I don't have any missing the 3.6V label line though.
Ordered some from a new chinese shop , more on Tuesday that i will have them in my hands …
Ha nice
Got 6 of the old batch
2 unused for later.
Thanks for the review
Thanks for the review, HKJ. I’ve been waiting for this one.
Cheers!
Can someone confirm the cells with the missing 3.6V text line are ‘fake’ or under performing?
I cant say for sure that “the fake ones” are realy fakes, cause they work and they perform like…lets say Keepower 4200 with our fed dd drivers, yet there is a difference with the better liitokalas
Good ones are like 5200-5300ma and have lesser int resistance, “fake ones” are like 4800-4900ma and have higher int resistance
What about this pic that teacher posted ?
Shows high capacity for the batteries with the missing line . But i guess it is because it is in charge mode
To be clear, the picture I posted came from This Post by Mitko in another thread.
I was using it as an example of the “missing line”. 
Since that pic keeps coming up, I sure would appreciate it if somebody would give me a shout out on how to work and read that charger! I’ve had one for a long time, virtually never use it. Mine seems to stop the charge at some 4.17V, I NEED those extra 3 hundredths of a Volt!
As far as reading internal resistance and checking capacity, I really don’t know how it works.
Got one last week .
When i mentioned the exact same line ( Mine seems to stop the charge at some 4.17V, I NEED those extra 3 hundredths of a Volt!
) to some people in another forum they thought i’m crazy 
Mine stops too at 4.17V .
Here are some words from HKJ’s review , i hope they help a little :
When display is flashing it is possible to select mode and current.
Using the slot button it is possible to reselect a slot and change parameters for it, also when charger is working.
When putting multiple batteries in the charger at the same time, it is possible to select mode and current simultaneous for all of them (Very nice).
When charging or discharging it is possible to use the DISPLAY button to select between V, mA and mAh.
The display button can also be used when the charge/discharge is finished, but the charger will change back to “full” display rather quickly.
Are the “the fake ones” suitable for high drain flashlights?
Thanks
Honestly, I don't like much the way the Opus-C3100 works: PWM charge current, PWM over its load current beyond the power supply's rating, fan, etc.
At times, I've thought how “easy” would be to attach inexpensive CC/CV modules to slider trays, mounting them with volt and amp meters (DIY crowd, of course). With knob attached external potentiometers, that would really be a li-ion/LiFePO4 “dreamcharger”. These modules are easy to buy for less than $2 a pop. Examples:
- 1/2/5/10Pcs Lithium Charger 5A CV Buck Step Down Power Supply Module LED Driver @cayin35.
- 5A Constant Current Constant Voltage LED Driver Battery Charging Module Portable @excellbay Tried these, my second unit is on the slow boat.
Cheers ^:)
I got 2 of the Opus chargers - one charges low, the other charges to bout 4.23V if you let it go til the end, just what I like
. So, I use the high charge one all the time - it's my main charger. I think I did the mode on this one to raise the charge limit.
But.... I also got the SKYRC - wow! You actually set the charge limit voltage. Now I can control that limit - no more worries bout charging hi or low. Plus it beeps when a cell finishes charging! Plus a whole lot more features. It's pricey, but the best around. I've wasted probably more money on chargers than what this one costs.
The way the opus works on the charge test mode. The capacity it shows is the discharge mah. When krs charging it says charging when the cell is full it goes to discharge. Once discharged the final mah shows up like in the picture above. Then the charger says charge again because its recharging the cell again. But the final capacity from the discharge will stay up it won’t change even when done charging until the cell is removed this is how it works. I got the very similar 5300-5400 on all 4 of mine first batch cells. I guess I can run another test on them. They have some cycles on them now maybe 40-50 two married sets.
IIRC The Opus BT-C3100 has an end voltage selector on it’s PCB to accommodate different chemistry, but you have to open it to get access.
@ patmurrris,
The Opus BT-C3100 can be opened to change from 4.2v to 4.35V or 3.6V on a small 3 position slider switch inside.
Beware however, as I ended up damaging the mini fan when I removed the back cover, as the Fan was partly glued in place (on Version 2.0), to be as quiet as possible. Howled once refitted!
I bought a new fan, now much quieter, and drilled a small slot (tip from another Member) in the bottom cover, so I can now change the setting, without any further dismantling being needed.
Hope This Helps,
Cheers,
S-L
I got the pair from Gearbest, nice!
Thanks Djozz.
Just ordered 4 from gearbest.