@Barkuti - for any sensitive systems you must use BMSs. You can have identical cells and one could still die-off way faster, therefore if you need to ensure balance you needs BMSs. Otherwise it’s an improvisation anyway. Other systems like flashlights of course won’t need any.
I pretty well understand all of that Overmind. Still, how about flashlights with 2 or more cells in series? Bad cell consistency increases the risk of over-discharging the weaker cell in such conditions, a flashlight driver does not have independent cell voltage monitoring. I am responsible of keeping my cells matched in any case.
This cell consistency problem means LiitoKala is doing something fishy with their cells, something which is more than proven already anyway. 
^:)
Well only long term testing can prove how reliable they are. Hope they are, as I got some quite at a quite cheap price.
Yea, I expected a drop to no less than 4.10V while still on the charger. The charge had been completed for a few hours, but likely no more than 3.
I’ll test this with a Samsung 30Q. Please hold…
A way to get a good idea of a given charger's slot measuring divergence is to do charge/discharge tests in it with the same cell or cells doing away with the older the cell, the lesser the capacity effect via swinging slot selection. Any cell is tested twice per round in each slot and its capacity averaged out of the two figures. For a 4 slot charger this is 1 2 3 4 then 4 3 2 1 or 4 3 2 1 then 1 2 3 4, as an example. Bear also in mind how does the charger scores the capacity figures, in a Lii-500 a mAh is scored only when the elapsed time per mAh has passed, thus any capacity figure should be added ½mAh.
I would unwrap the cells and carefully look for factory markings, top and tail shape, condition, etc. For sharing, making good and detailed photographs is of help. 
^:)
Well, the Samsung 30Q measured fine at 700mA. I received this cell from BG 3 months ago and this was only its 3rd charge, so I consider it new. I was busy elsewhere when the charge completed, but no more than 1 hour had passed since completion. Notice that the voltage dropped to 4.02V, which is nearly identical to what we saw with the Lii-50A. I used the same bay for consistency, but I will test with another bay tomorrow (~12 hours) if it helps.
So far, the capacity measurement seems okay, but the substantial voltage drop is bizarre. I don’t like to cycle cells unnecessarily, but I apparently need to do more testing and actually witness a charge cycle ending. I do know, however, that the cycle reaches about 4.20V as I witnessed voltage at 4.18 and rising when I last pulled the Lii-50A.
I did initially start on-topic as I was showing the capacity of an Lii-50A in this charger, but now that I’m discussing an issue with the charger I would be happy to move my issue elsewhere if anyone prefers.
Looks like the charger does not disconnect the cell after testing. That’s not a good design if you intent to test over night.
You think it fully charges the cell then starts to discharge it? Possible I guess.
You would need to remove the cell after charging and maybe use a DMM to check voltage. I suppose it should be at 4.20 to 4.18. Then let the cell sit several hours and see if the voltage drops a little or a lot.
The capacity for that 30Q seems fine so it’s probably not reading high. That’s odd, I thought the PLB-55A cell was the highest capacity at about 5750mah. Interesting.
That wouldn’t be a good design, period, but other people are not reporting this issue with this charger, so it’s possible that there’s something wrong with either the charger or just bay #1. When I made the first post, I was mostly reporting on the currently-shipping Lii-50A capacity, but while cropping the photo I noticed the 3.96V reading and began wondering. Now I have a mystery to solve, though I didn’t want one 
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Unless the cell has some wear-down, there is no reason to drop voltage that fast.
Also, a 30Q should not show under 3000mAh, specially tested at low current, unless again it has wear-down.
I don’t think that’s true. Most 30Q’s test under 3Ah.
Here's HKJ's test:
/Samsung%20INR18650-30Q%203000mAh%20(Pink)-Capacity.png)
And here's zeroair's recent test:
Zeroair does get over 3000mAh, but only at 250mA. I don't have many li-ion cells to choose from, but this one makes a good test case as it's a known quantity and Samsung has very high consistency with them. The above tests were done 3.5 years apart, but the shapes of the curves are largely identical. The 2019 cells do seem to have somewhat higher capacity at low currents, but this could be an artifact of different test environments.
I cannot agree. Take a look at HKJ's 30Q test. Bear also in mind that final cell voltage (which depends of maximum charge voltage, path resistance and cut-off current) affects the capacity measurement, along with cut-off voltage and discharge rate. In my experience maximum charge voltage varies between charger slots, at least in my Lii-500 does.
That’s too strange. I never encountered a Samsung Q-cell to test under it’s specs. Cells tested: dozens of 13q, 15q, 20q. Tester used: Opus C3100 v2.1.
Not strange at all if you are using the Opus, they are known to be ‘optimistic’ in their readings. In other words, they are known to read high.
on aliexpress i see sellers of these sells with tons of positive feedback but in the photos, i see various mOhm reading. 24-70mOhm 
@500-1000mA. not sure what to make of it. i need 5 cells in series. do i buy a set and hope for best of matching mOhm? or should i get something else?
Analyzing chargers do not measure the DC internal resistance of cells, they measure 1KHz AC internal resistance as far as I understand. Additionally, the problem is they measure “at the circuit board”, this means they are measuring battery plus contacts plus rail resistances. Bear in mind that rail and contact resistances are of similar order of magnitude to a cell's internal resistance, and wildly variable at the hands of uninformed, couldknowbetter or careless users.
Personally I’d get something else. Assuming you have access to other choices and don’t mind spending a bit more money.
Chargers measure DC resistance, it would require some extra circuit to measure AC resistance and you do not find that in a normal analyzing charger,
I will correct myself then: I think the Lii-500 does not measure DC internal resistance. I know this because of a self-made extended cell capacity test in which I ensured minimization of rail and contact resistances before each discharge cycle. Check my Lii-500's internal resistance values for that test here: KingWei 18350 1000mAh 900mAh test.
Why do I know the 51 - 69mΩ displayed values are spurious? Because I later measured each cell's DC internal resistance by injecting DC current into them with my precision power supply, recording corresponding changes in cell terminal voltage and using those figures to obtain true DC internal resistance. I obtained a consistent average of ≈110mΩ. Two cells scored a 104ish - 105ish mΩ minimum while another a 116ish - 117ish mΩ maximum; they came packed up in pairs with a plastic wrap.
Henrik I must say I do not see how chargers, as a whole, use direct current internal resistance measurement. I've seen a lot of figures from different chargers here and there and I do not feel like they are doing that.
