Nitecore UM2 cooked my old AA nimh as a li-on battery?

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MyBatteriesMayb...
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Nitecore UM2 cooked my old AA nimh as a li-on battery?

Hello everyone,

I just got the Nitecore UM2 charger. According to this review https://lygte-info.dk/review/Review%20Charger%20Nitecore%20UM2%20UK.html it should be able to differentiate between NiMH and Li-Ion batteries. I have some old Varta 2600 mah (dubious claim) AA batteries. They’re approximately 8 years old. Maybe even older.

I put them in the Nitecore UM2. They were recognized as AA NiMH batteries and charged at 500mah. The charger has a cut off so later I just looked at them again. 1 of the batteries had stopped at 1.47V… but the other one was on 2.4V and in Li-Ion charging mode!!

How is that possible?! What happened there? I’m a total newbie when it comes to batteries so i am confused. I bought a smart charger for battery safety

The battery feels almost burning hot to touch, and i can see a very small round bulb now in the side of the battery that was not there before…

zoulas
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The charger may be broken. Either that or your batteries were so old the charger could not properly identify them.

Robin Dobbie
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I had some old NIMHs that my charger(not nitecore) thought were lithiums I’m guessing because their capacity was so low the voltage shot up too quickly.

MyBatteriesMayb...
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zoulas wrote:
or your batteries were so old the charger could not properly identify them.

How would that process work?

ChrisGarrett
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MyBatteriesMaybeGotFried wrote:
zoulas wrote:
or your batteries were so old the charger could not properly identify them.

How would that process work?

You probably just missed a termination, in that the charger failed to manage the voltage/temperature.

I’m guessing that it’s the older battery’s fault.

Chris

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Older batteries with high resistance can go from a low voltage to an apparently high voltage quite rapidly. It’s a possible glitch/artifact of the charging process. The ‘smart charger’ isn’t THAT smart. It can’t actually tell LiOn from NiMh. It works on voltage.
Maybe the voltage shot up too fast, the charger thought it was lithium, and set to work on a false assumption.

BTW – those were never very good NiMh batteries, and 8 years has absolutely done them no good. It’s probably prudent to recycle the lot of them. I’ve got some OLD Annesman that are like that and I have to watch them very carefully. They WILL miss termination and put 5000mA+ into a battery designed for half that.

To Air is Human, to Respire….Divine.

d_t_a
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That doesn’t only apply to your charger.

I have a few very old Eneloops (circa 2006-2007) that have very high resistance — they will still work on very low drain devices (probably not more than 100mA or 150mA devices) or flashlights in the Low mode only.

I keep these (my very first Eneloops) around for testing chargers nowadays, not really use them for anything else.

I’ve noted that on several chargers, either the charger refuse to charge it, or on some chargers, it will not properly detect (or will jump to Li-Ion setting).

In particular I think that happens on the Xtar VC2S and VC4S, which shows probably the same behavior as your UM2. The chargers will detect these old batteries as NiMh, then later when it’s trying to charge, detects as Li-Ion (as displayed on the charger) and sometimes goes back & forth between NiMh & Li-Ion setting (I removed the battery after observing the behavior, so I’m not sure if it really charge the battery or not).

I notice that the Miboxer C8 will properly charge this battery (but takes a very long time, as it uses the lowest charge current of 0.10A).

My SkyRC MC3000 used to be able to charge these batteries at a low charge current, but right now, even if I select low charge current, the MC3000 will show “connection break” error message after awhile of charging these batteries. The IR reading (on the MC3000) for these old Eneloops is more than 2000mOhms already.

gravelmonkey
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I had same happen to me a few weeks ago.

Charging a pair of fairly old, standard NiMh AA, energiser cells (silver wrapper with green writing), one charged fine, I caught the other a while later, with many more mAh recorded more than the first and/or the capacity of the cell (I can’t remember, but it would have been around double or more to shock me like it did)… Cell was extremely hot to touch and wrap was blistering.

Must say, as I’ve not had the UM2 long, I’m pretty annoyed… I don’t get why everyone is blaming the cells, I’ve charged these many times with Zanflare C4, Nitecore D2, and other multi-chemistry chargers without issue, yes I’m sure high internal resistance makes it difficult, but Nirecore consider themselves a premium brand, and should be capable of making a safe charger…

Do these things not have temp protection in them or what? Shame HJK rates it fairly well on his comparison site if it has such massive problems…

Edit to add: I didn’t actually see if the display had switched from NiMh to Li-ion, I pulled the cell and unplugged the charger extremely quickly as I was very concerned.

ChrisGarrett
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500mA is only .2C and that might just be a little low to trigger any termination, but I can’t say for sure.

Chris

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So wait I’m curious now. What if i put in a brand new AA nimh eneloop inside the charger that is already 90% charged… will the charger notice the voltage rise too fast and think it is a Lio-Ion as well or am i misunderstanding this?

ChrisGarrett
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MyBatteriesMaybeGotFried wrote:
So wait I’m curious now. What if i put in a brand new AA nimh eneloop inside the charger that is already 90% charged… will the charger notice the voltage rise too fast and think it is a Lio-Ion as well or am i misunderstanding this?

First of all, I’m no EE, but a well implemented charging circuit is different for NiMH and Li-ion batteries/cells. They have different charging protocols, even though your charger does both.

For NiMH, ideally it’s dV/dT, voltage and temperature and for li-ions, it CC/CV, constant current, constant voltage.

They act independently depending on the voltage of the battery/cell being inserted.

Try starting with a fresh set of Eneloop/Fujitsu set of batteries, discharge them down to say…1.20v and then charging them back up and measuring the elapsed time.

Chris

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I never liked those multi chemistry chargers that recognize the cell chemistry automatically. I always felt that there is possibility for something like this to happen.
Before I got a MC3000, I used my very old MAHA C9000 for NiMH and a separate charger for LiIon only.

zoulas
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I agree, two different chargers is ideal.

gravelmonkey
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zoulas wrote:
I agree, two different chargers is ideal.

Not while travelling….!

That said, I do have a bunch of chargers, go-to at home is the Zanflare C4 for both NiMh and Liion, I live in a small house so all my gear packed into cupboards, accessing two seperate chargers is a PITA.

Currently travelling for work, I’ve got the Nitecore with me, I’ve only got a couple of NiMh cells to charge, I’ll do them on my desk while I work so I can watch them like a hawk…

Vapcell U2 arrived shortly before I left, I didn’t have a chance to fully test it, so I couldn’t justify bringing it with me.

NiOOH
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For traveling, I use a Panasonic BQ-CC16 for NiMH and Xtar VC2S for LiIon. The combined volume and weight of the two is less than that of a MAHA C9000 or many 4 bay universal chargers.

zoulas
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I travel also. And when I do I take extra batteries with me. Its a lot easier than bringing a charger.

gravelmonkey
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NiOOH wrote:
For traveling, I use a Panasonic BQ-CC16 for NiMH and Xtar VC2S for LiIon. The combined volume and weight of the two is less than that of a MAHA C9000 or many 4 bay universal chargers.

I’m not saying my solution is best, I only want to travel with one charger… I don’t want to carry additional weight or bulk… Charger advertised as doing both NiMh and Liion, so it’s not unreasonable to expect it to perform as advertised… Question

zoulas wrote:
I travel also. And when I do I take extra batteries with me. Its a lot easier than bringing a charger.

As above, whatever works for you; logic for this trip: I’m out for 8 weeks, hard to predict my useage, I may only charge once, may charge 10 times.. impossible to budget for that kind of use for carrying spare cells..

Plus, I hate going through airports as it is, I don’t need to be pulled aside and questioned why I’m carrying a bunch of extra liion cells…

NiOOH
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gravelmonkey wrote:

Charger advertised as doing both NiMh and Liion, so it’s not unreasonable to expect it to perform as advertised… Question

I agree with you 100 %, these things should work as advertised and expected. Unfortunately, this is not always the case, and your case is not the first one I hear of. That is why I decided to play it safe and use two separate chargers.
The only charger I trust with multichemistry duties is SkyRC MC3000, but there, you select the chemistry manually during programming, and it’s way to bulky for traveling…

zoulas
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One charger for both can absolutely positively work as long as you don’t do foolish things like use dead batteries from old laptops or 10+ year old eneloops. If you are using batteries less then 5 year old, you should have no problem whatsoever.

NiOOH
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zoulas wrote:
One charger for both can absolutely positively work as long as you don’t do foolish things like use dead batteries from old laptops or 10+ year old eneloops. If you are using batteries less then 5 year old, you should have no problem whatsoever.

That’s also true, but the manufacturers should state it clearly in their literature or implement safety features that wouldn’t allow such things to happen, no matter what.

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zoulas wrote:
One charger for both can absolutely positively work as long as you don’t do foolish things like use dead batteries from old laptops or 10+ year old eneloops. If you are using batteries less then 5 year old, you should have no problem whatsoever.

Yeah but those Varta batteries worked fine whenever i used them.. I mean 12$ for a smart charger is a great deal but still I’m kind of worried now. I thought smart chargers could be ‘charge and forget’ for family members but i guess it is not so.

zoulas
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NiOOH wrote:
zoulas wrote:
One charger for both can absolutely positively work as long as you don’t do foolish things like use dead batteries from old laptops or 10+ year old eneloops. If you are using batteries less then 5 year old, you should have no problem whatsoever.

That’s also true, but the manufacturers should state it clearly in their literature or implement safety features that wouldn’t allow such things to happen, no matter what.

I disagree. Manufacturers can’t prevent people from being stupid.

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zoulas wrote:
NiOOH wrote:
zoulas wrote:
One charger for both can absolutely positively work as long as you don’t do foolish things like use dead batteries from old laptops or 10+ year old eneloops. If you are using batteries less then 5 year old, you should have no problem whatsoever.

That’s also true, but the manufacturers should state it clearly in their literature or implement safety features that wouldn’t allow such things to happen, no matter what.

I disagree. Manufacturers can’t prevent people from being stupid.

How is the fact that I used older batteries that still worked in my devices stupid? Facepalm

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MyBatteriesMaybeGotFried wrote:

How is the fact that I used older batteries that still worked in my devices stupid? Facepalm

At 8 years old and with batteries of questionable origin, they’re most probably toast.

Just because you can fire up a light on the lower modes, doesn’t mean the batteries are healthy.

Put a 1A drain on them, which isn’t much these days and time how long the light stays on.

Chris

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I disagree with the blanket statement that batteries 5/8 years old are toast and using them is stupid. I have many Eneloops and 18650’s that are at least 10 years old and they seem to be holding up well. I test all my Eneloops every 6 months and the old ones have basically the same capacity as when I got them as well. Granted I can only discharge at 1A on my Opus 3100 but in actual usage I don’t notice any difference. I don’t test the 18650’s often but when I do they don’t seem to be much worse for wear than before (other than a couple that are toast Big Smile ).

My batteries don’t have that many cycles on them because I rotate them during usage. My 10 year old Eneloops probably only have 20 cycles on them not counting testing. Many of my non-Eneloop NiMh did go bad though after a year or 2 Angry

Maybe it’s more accurate to say that batteries used hard and often and aren’t high quality don’t last that often?

ChrisGarrett
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SIGShooter wrote:
I disagree with the blanket statement that batteries 5/8 years old are toast and using them is stupid. I have many Eneloops and 18650’s that are at least 10 years old and they seem to be holding up well. I test all my Eneloops every 6 months and the old ones have basically the same capacity as when I got them as well. Granted I can only discharge at 1A on my Opus 3100 but in actual usage I don’t notice any difference. I don’t test the 18650’s often but when I do they don’t seem to be much worse for wear than before (other than a couple that are toast Big Smile ).

My batteries don’t have that many cycles on them because I rotate them during usage. My 10 year old Eneloops probably only have 20 cycles on them not counting testing. Many of my non-Eneloop NiMh did go bad though after a year or 2 Angry

Maybe it’s more accurate to say that batteries used hard and often and aren’t high quality don’t last that often?

Batteries… both NiMH and li-ion will develop high I.R.s over time.

I have 16 Sony 18650s harvested from VAIO packs that are date coded 2002.

They still have 75% of their capacity, so with quality stuff, you’ll get longer life, but things still go bad and just wear out.

Only way to know is to test them under known loads and in an analyzing charger.

Chris

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I have just bought 2 of the nitecore um2 from banggood for a ship price of $27.59. Some may be wondering why I bought 2, well I have many batteries and I have 10440 batteries which according to hkj this can charge them 0.1amps upwards.

The question is can use these power supplies? I am assuming the charge i will get for the first one is 1amp per battery and the second one I’m not to sure. Is the first one 2.1amps per USB port or 2.1amps shared?

https://www.wilko.com/en-uk/masterplug-13a-3-socket-fused-adaptor-with-2...

https://www.wilko.com/en-uk/wilko-plug-through-usb-surge-adaptor/p/0455043

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My Nitecore UM2 charger works fine with all kinds of rechargeable batteries.
HOWEVER
The USB A/C power adapter matters. I’ve found some will cause lag or errors in the UM2 UI (display won’t change, buttons stop operating), or insufficient power to properly charge the cells. Maybe there’s a scenario where a deficient power adapter can thwart proper regulation in the charger, incurring an overcharge?