MiBoxer C4-12 overcharges INR18650-30Q to 4.48v!

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. :open_mouth:

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. :frowning: Maybe I’m dramatizing the overcharging, I don’t know.

I think Miboxer has sold hundreds if not thousands of this model charger. I’ve heard a handful of people say they’ve gotten an error message On slot 3 and DTA got an overcharge once and it never happened again.

I do think you’re overreacting considering the small percentage that have had a problem, but it’s important that you buy something that you feel good about. If you’re getting bad vibes from the C4-12, that’s okay. There are a lot of other chargers to choose from.

I don’t think there’s many to choose from that can do 3 amps x 4, though. Most chargers do 1 amp x 4. If you want a simple charger that can do 2 amps x 2, Xtar makes the SV2 Rocket. I’ve got some of those. They only have 4 different charge rates, though. Sometimes they are on sale under $20 each.

I’ve only got one C4-12 and use it all the time. I’ve had zero problems from it. I’ll report back if it starts to act up.

There are no flawless products, and unhappy people are more likely to express their displeasure than happy people.

That said, AFAICT, MiBoxer is new to the game, and has only been selling chargers for little more than a year.

Their original charger, the C4, was found not to terminate.

Their next charger, the C2-3000, initially had an automatic mode that some felt used too much current for smaller cells. To their credit, they quickly came out with a revised version that allowed manual current override*, and I believe the C4’s non-termination behavior has also been addressed.

I haven’t followed the C2-4000 and 6000 too closely, but haven’t noticed any common complaints about them.

The slot 3 glitches do seem to be a shared issued with the C4-12.

This overcharging incident could be an isolated incident, or there could still be some uncovered bugs in the software*, which may need further refinement.

The company may have some growing pains, but if they work diligently to address the current issues, and to prevent others from occurring in the future, it will do well, as the products are otherwise appealing. If it doesn’t, then it may find that its tenure as a charger maker will be short-lived.

  • the software-controlled nature of these chargers seems to be a double-edged sword thus far. If users are to put their trust in it, it needs to work reliably and consistently, which some find may not be the case.

+1

I wish the number of incidences of members having problems was matched by information on the number of the chargers that members have bought as well as things like manufacturing date. How many active members does BLF have? IMO not enough info to judge the severity of the situation or determine whether it was a bad batch of components or a design flaw. I worked in QA and reliability engineering for 20+ years and have seen just about every failure cause imaginable.

I asked this question awhile ago and never got an answer, I finally got an answer from Miboxer about 3 weeks after they sent me a new charger so now I have two of them
They told me that the reason is exactly what you suspect, slot for provides power for the power bank function and this causes the lower voltage and is nothing to worry about, you are good to go.
As an aside, I’ve had no issues with either of mine but have to add that they only get very lite use at this time.
If Miboxer had not added the power back function and made it an analyzing charger I think I would have made this my primary charger.