I’ve had a similar kind of issue with a hobby charger where a particular bay will charge differently to the rest no matter what battery pack I plug into it. Also the issue (for same battery packs) never showed on a different charger. So I don’t think it’s an IR issue rather a discrepancy within the charger. Sad to here so many people having issue with this charger. I recently bought an Adeaska so I’m kinda glad I didn’t end up with a C4-12 but don’t actually know much about the Adeaska reliability.
Well if mine is stuffed might as well pull it apart and see what is going wrong.
Yes please. If you can, post high-res pics of the PCB including part designators and case markings. I’d be especially interested in the SMPS ICs and what I assume are charge controller ICs for each charging path…
edit Never mind the pictures, the relevant ones all seem to be included in Lexel’s review.
I’ve had mine since late October. Knock on wood, so far no issues with slot 3 or any other slot, for that matter, other than the charger rebooting itself after a while due to overheating if I charge all 4 slots at 3A.
This might be a really stupid question, but is possible the software is screwed up between voltages of NiMh and Li-ion?
I only ask because I’ve just opened the C4-12 I won in the MiBoxer competition and spotted that termination voltage for NiMh is 1.48 v.
Just a coincidence?
But why would it only be screwed up on slot 3?
Does output voltage in open slots (without a cell) mean anything? Mine is as follows:
Slot 1: 4.97V
Slot 2: 4.97V
Slot 3: 4.97V
Slot 4: 4.86V
Wondering why they are not all the same. Alas, slot 4 is also used for power bank function, so maybe the added circuitry affects open voltage.
What are you guys seeing on yours, especially those of you that are having problems with Slot 3 overcharging?
My $0.02 & Possibly good advice: Put electrical tape over the poles on slot #3 to ensure you don’t inadvertently put a cell there. If it were me, I think I would discontinue use of the charger completely. Everyone here on this forum knows the dangers of Li-Ion use, more so over-discharging not as much overcharging, but still risky.
It is quite ridiculous that a new charger should have any issues of this sort at all. Mi-Boxer apparently has do QC issues…
Mine was returned so I can not test.
Two new ones are in the box un-opened.
That is about perfect termination voltage for NiMH cells they should terminate around 1.5v. That voltage will drop when the cell settles the voltage should stabilize to around 1.3/// any where around there. Newer cells may sit at 1.38 older cells around 1.32 maybe?
Depending on the age and quality of cell.
I for one learn from the experience of others.
Stumbled across this thread, after recently placing an order for this charger with GearBest. I hope mine doesn’t have problems with slot 3. 
Seeing as how each slot seems to have independent circuitry based on the ability to set separate current and other parameters by individual slot I would expect that any slot could mess up. Minor performance variations would be expected due to component variations. HJK also says slots are independent in his review as I recall.
I note too looking on Amazon apparently the same charger is being sold under multiple brand names. At least two Miboxer chargers are also apparently being sold under the name Kinden on Amazon based on photos and specifications so far as I can tell.
d_t_a just curious, why did you post this same thing twice? and both on the same day
He said one thread was about the charger and one thread was about the battery.
Thanks JasonWW.
So this thread is about the MiBoxer C4-12 charger… anyway, I’ve been using the charger (but still keeping a close eye on the charger regularly… ) and it has not reproduced the same overcharging. I dare not place my Samsung INR18650-30Qs (I only have 4pcs right now, and a couple of my additional orders of 30Qs are either cancelled or are taking much longer than 2 months to arrive).
Thus far, the only high-drain batteries I’ve been regularly charging in the C4-12 are Sony VTC6 (which almost always hits 3.0A charging current automatically due to their low resistance reading by the charger.) None of the VTC6 have experienced the “overcharging” mentioned above yet though.
Man this charger spells trouble. At first I thought about getting one, but after reading about all these problems… And a charger overcharging cells is really something I don’t want to happen ever.
All charger brands have a few bad ones from time to time. Just like you ocassionally get a bad flashlight sometimes. If you only bought perfect products, you would own nothing! Lol
I just discovered this thread and it reminds my of my input I left here
My C4-12 was in error on slot 3 and 4, indicating unreasonable values for internal resistance. Slot 4 even indicated “NiMH” instead of “Li-Ion” when putting in a brand new Samsung 30Q Button Top. Fortunately, Amazon has a very uncomplicated return policy, so I sent it back. Mine was sold from “Kinden” on Amazon.de, see here.
I mean you got to admit there’s a lot of negative reports coming in about this charger lately. And there’s a little difference for me between having just “some” malfunction or actually a fault that threatens my home and health. 
Maybe I’m dramatizing the overcharging, I don’t know.