Panasonic NCR18650 (2900 mAh) & Pila IBC Experience: Very Warm.

Bolster

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I'm new to 18650s. Purchased two NIB Zebralight H60w headlamps, spend a long time researching which cells were correct, finally went with Zebralight's own recommendation, the UNprotected Panasonic NCR18650s. (The H60 is sensitive to overly-large cells, and most of a protected cell's functions are covered by this particular battery and the light's electronics...more on that later if you're interested. For now, remember it's the manufacturer's recommended cell.)

Researched chargers. Purchased a new Pila IBC charger. Here's what happened.

All voltages measured with no load. I took notes during charging so assume times are accurate w/in 10 minutes. The time line:

Cells arrive in the mail, 3.66V each.
Start charging 6 pm in new Pila IBC charger.
By 6:30 pm I note I can rest my fingers on the cells (with moderate pressure) for 5-6 seconds before needing to remove my hand.
By 8:00 pm 5-6 seconds is still possible but not pleasant. Unplug the charger. Take voltage at 4.04V each.
Research CPF for info. Get advice in the parent forum, to post in the Hot Cells subforum.
8:30 pm, cells are room temperature, voltage now 4.03V each.

Where do I go from here? Did I do something wrong?
 
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lightseeker2009

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At what rate does this charger charge the batteries? My charger is at 500mah and not even no name brand batteries gets hot at all. They don't even get warm.
 

lightseeker2009

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Well if it gets so hot that you must remove your hand in 5 to 6 seconds, then I would say something must be wrong. Batteries must never get so hot as to be able to boil eggs on:)

My advice is to test other batteries as well as to test these batteries in another charger. I think they are far too hot.
 

hazna

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My advice is to test other batteries as well as to test these batteries in another charger. I think they are far too hot.

+1
Helps to isolate what the problem is whether it is the cell or charger. Do you have any other 18650 batteries?

Also try fully charging the battery and measure the voltage when immediately green. Let the batteries rest for half a day and measure the voltage again. Does it drop by much?
 

srfreddy

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My 4sevens charger did that once, because of the bug. It was pretty much putting as much current as it could pull from the wall into the cell. Not good.
 

SilverFox

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Hello Bolster,

I agree that something is not right. Cells in the Pila charger will warm up, but they shouldn't get hot.

Take extreme caution while trying to figure out what is going on. Charge in an open area with good ventilation, and charge on a surface that is heat resistant.

You need to figure out if it is the charger or the cells that are having issues. To check the charger you can monitor the process and log the cell temperature during charging. You will have to find some way to measure the temperature, but you should have a thermometer around the house that you can press into getting an idea of what is going on. The cell temperature should be below 140 F for safety, and most cells never exceed 110 F.

If the cell heats up to hot, terminate the charge. If this happens quickly, the cell could have higher internal resistance. To check this out you need to try to charge another brand of cell. If that cell also heats up, this would bring suspicion to the charger.

The Pila charger has a good reputation, but that doesn't mean that a questionable one makes it out every now and then. My first guess is that there is an issue with the cells, but I am open to an issue with the charger as well.

Tom
 

Bolster

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Thanks for the replies. So it's either the cells or the charger, is it?

Let's start with the charger, and eliminate it from suspicion. How can I directly test the amperage of the Pila charger with my VOM? I'll return it if I can prove it's defective.

I assume simply putting an ammeter "in series" in the charger is not good enough? Ie, one lead to the negative contact of the charger, other to the positive, probably wouldn't work? (EDIT: Yep, doesn't work. Charger's smart enough to know it's a VOM in series, not a cell.)

If that won't work, is there a way to test amperage "in series" with the battery? Route a wire from the charger's negative contact to the negative of the cell, then the ammeter connected from the battery positive to the charger's positive lead?

I should be seeing 600 mA, yes?

In other news, popped one of the cells in my H60w last night for a quick test...wow, what a wonderful headlamp. But not running it except for a quick test until I figure out what's what with the charger/cells.
 
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Glock27

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I would think that without buying another cell, your best bet would be to finish charging ONE cell at a time until the charger terminates. Measure voltage. Continue to monitor voltage on the charged cell(s) and watch for voltage drop. If they taper off quickly, the cells are the problem.
I would be very wary of putting a meter in line to measure current without a EE giving good instruction.
It's a bummer for you to have 2 great lights and can't fully use them yet.
I would be willing to drop a used cell in the mail for testing. Give me a PM. You could take the postage off my future mount ;-)

G27
 

Bolster

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flashlight-test-pila.jpg


Tested the Pila for amperage by putting my VOM in series (on the 10A setting so milliamps will read as decimals). As you can see, .67 of an amp, or 670 mA. The leaflet with the charger says 600mA.

Bad charger? It's putting out 12% over its rating. I don't like those numbers.

(Oops, sorry Glock, just read your post. In this case I think asking for forgiveness will be easier than asking for permission, eh? Thanks for the cell offer, tho!)
 
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Bolster

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Decided to return the Pila charger. The retailer also agreed it should not be putting out 670 mA.

I don't have the patience for Li-Ion, I fear. I'm playing out of my league. I now have 2 Panasonic NCR18650s for sale, and two Zebralight H60w's, as well!

BTW, the cells are holding their charge. Both sitting at 4.03 V where I left them yesterday.

A big thanks to my CPF friends who helped me figure this out.
 
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Glock27

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Bummer! It's a shame that you had a bad experience. You ordered "the best" of both charger and cells.....this should have been real easy.
Li-Ion is intimidating and scary because of all the stories of potential danger....houses catching fire, limbs being blown off, hundreds of people killed.:ohgeez:
I'm not convinced that the cells were not at fault. 600 mA is normal output for a cell with a specific resistance. If the resistance of the actual cell is higher than expected, perhaps that accounts for the 11% greater current.
When I first got into lights I was all AA Ni-MH. I've sold or given away all but my headlights (H50s & 501w's). Li-Ion gives you so many more choices, higher power density, more light…and a form factor that feels so much nicer in the hand IMHO.

G27
 

hazna

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670ma charge rate doesn't seem to be too bad. There could be some variation betwen various chargers and theres also the chance that your DMM is not giving you a 100% accurate reading (especially if it's a cheap one). 670ma charge rate shouldn't damage your cells any more than a 600ma charge rate.

Don't give up too quickly, I think you should consider trying another battery instead. I'm a little suspect about some of the panasonic ncr18650 from hkequipment...
 

VegasF6

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Decided to return the Pila charger. The retailer also agreed it should not be putting out 670 mA.

I don't have the patience for Li-Ion, I fear. I'm playing out of my league. I now have 2 Panasonic NCR18650s for sale, and two Zebralight H60w's, as well!

BTW, the cells are holding their charge. Both sitting at 4.03 V where I left them yesterday.

A big thanks to my CPF friends who helped me figure this out.

Don't give up just yet Bolster. You are doing everything right, we will figure this out. I have a couple suggestions, despite it seeming like a waste of money, consider buying another pair of cells, even if they are budget brands. Even if they don't fit in this headlamp, you are bound to want other lithium powered lights in the future, after all its an addiction :)

Also, I didn't think to offer this earlier, but I would be more than happy to try and charge those cells for you on my hobby charger and see if they give me any trouble.

Third, (ly?) and I will want the other guys advice here, I would think you could go to a local electronics store and pick up a 3.3 ohm 10 watt resistor, and short the leads across that Panasonic battery. This should effectively give you about a 1.2 amp draw on the cell. Leave that on for say, I dunno 15 minutes or whatever and monitor it. If the battery feels very warm to touch while discharging, it's definitely the cell. I would THINK, (but this is theory) if that cell has excessively high internal resistance causing heating during charging, it would also do so during discharge.

I wouldn't think that 670 mA from that Pila is to excessively high, but it would depend on what state of charge your cell was at also. If it was already over 4 volts it should have entered a constant voltage stage of charge with current tapering off.
 

Aircraft800

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I have 6 of the NCR18650's, I don't like them at all. I have 3 chargers, a TrustFire, and 2 hobby chargers. These cells have always been a problem for me charging at a 1/2C ~ to a 1/10C. They seem to never reach 4.1~4.2v I usually end up terminating the charge because the cells get warm, but similar Li-Co cells never warm up at all. I wonder if there is a better charger for these newer chemistry cells?

Sent from my PC36100 using Tapatalk
 

jasonck08

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Could they be fake or used cells?

670mA is NOT a high current to charge a 2900mAh 18650 cell at.

I frequently charge my 2900 cells at 1.5-2A on a hobby charger and they never get noticeably warmer than room temperature...
 

Aircraft800

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670mA is fine for these cells, they have a Max charge current of 0.7C, or 2A. I wonder if these Nickel oxide based cells behave differently by design?
 

Bolster

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Hi folks. A sincere thanks for taking interest in my travails. Just following up on a few comments or questions. I agree we don't have a diagnostic on the cells yet, but we do have a diagnostic on the charger. The cells are holding their charge so far. Somewhere here on CPF I read of another CPF'er stating that his new Panasonics needed several charge/discharge cycles before the internal something something broke up or dissipated (see, I'm in over my head) which in turn lessened the internal resistance. Can't find that post now, and that's just from memory...may be misremembering something here.

However, I'm caught in a moment where I have almost zero time to experiment further with these. Besides normal work duties, I'm also studying for a ham radio test, concurrently taking a CERT class, preparing a summer graduate class, and trying to buy a house! So for the near future I just need a headlamp that works, not one to fiddle with. The second issue is, I foolishly discussed the H60w & cells issue with my wife. Her firm opinion was that her husband, who carries three advanced degrees in his head (none of which help him understand or design flashlights in the remotest way), had better not be putting any Lithium Ion anything near his skull.

Thus Spake the Wife.

Maybe I'll get interested in this again after 4sevens gets his charger fixed and on the market, and can figure out a way to use the headlamps only when SWMBO isn't around, but this Pila is going back. Haven't decided what to do with the cells yet.
 
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