XTAR VC2 not fully charging?!

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zoom zoom
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XTAR VC2 not fully charging?!

I've been using the charger for about 4 days now and since day one I have noticed the batteries don't come off the charger reading 4.2V. At first I wrote it off as maybe my voltmeter was off, but I have had a chance to run a couple batteries through my other charger and compare run times simultaneously.

 

My other charger is a cheap one, generic 2 battery charger, and the batteries consistently come off it reading 4.3-4.4V. The XTAR is giving me different results with each battery, some come off as low as 4.13V, while most are 4.14, some get up to 4.17, and ONE battery was at 4.18V. I've noticed the digital voltmeter also usually jumps to 4.2 prematurely. It will say 4.2, and keep charging for several mAH. I ran one battery down to 2.75V to see what the charger would do with it. It said 4.2V within 30 minutes, and continued to charge for about 16 hours loading the remaining 2200 mAH for a total of 2758 mAH in a battery that is supposed to  be rated at 2400mAH. When I took it off charge, it only read 4.17 with the voltmeter. I stuck it on my old charger and it continued to charge for 3 hours and came off at 4.23V.

 

anybody else had similar issues? Is there something wrong with the charger or ...?

Edited by: zoom zoom on 01/24/2015 - 00:13
old4570
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Wow , _ U have a serious Problem !

Lets start with one problem at a time ...

Termination voltage ..  Termination voltage is variable possibly due to the condition ( internal resistance ) of each battery ..  The lower the termination voltage , quite possibly the higher the internal resistance .. If you buy a smart charger , the charger may take notice of the resistance to charging and terminate earlier .. One way to check against this is with an old brute force charger ( Trustfire TR001 = Responsible for a few flame events , but never mind ) ...  So if you have one of these older chargers , charge you batteries in that and hope it sort of terminates at 4.2v ..  The thing to do is check voltage on removal from charger , then check again about 2 hours latter and see what the resting voltage is and check the variable ..  Good batteries may possibly sag as much as 0.01v  ( 4.2 - 4.19v ) or not at all .. ( Not at all = Very good )

  Other charger :

Consistently charged to 4.3 / 4.4v  , ..........................  Holly smoke batman !

Eeeeeeer , that's .................................. BAD !   And over time would stress the batteries and quite possibly increase the speed of degradation by some margin . 

4.2v Prematurely :

Ok , Im not there to see for myself , but at a certain point the charger will indicate 4.2v .. The gauge is somewhat coarse ,  so ???? ( Not the end of the world )

And yes it may indicate this for quite some time , especially with larger batteries ....

Current in VS current out :

Yes , usually ( like 100% of the time ) more energy goes into charging a battery than discharging a battery ... ( Physics )

There is a certain amount of Variable loss in charging ( energy ) so to put 2600mA into a 2600mAh battery may take 2900mA or more depending on those nasty variables . 

 

 

 Always remember , the easiest thing in the world to do , is to expel hot air from your lungs and through some vocal chords ..
The resulting sound may , or may not be worth listening too ….

 

hank
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Your first cheap charger is unsafe. Your new one is doing it right.
You can look this stuff up: https://www.google.com/search?q=li-ion+cell+overcharge
finds, for example, this:

Quote:
The lithium ion battery is easy to charge. Charging safely is a more difficult. The basic algorithm is to charge at constant current (0.2 C to 0.7 C depending on manufacturer) until the battery reaches 4.2 Vpc (volts per cell), and hold the voltage at 4.2 volts until the charge current has dropped to 10% of the initial charge rate. The termination condition is the drop in charge current to 10%. The top charging voltage and the termination current varies slightly with the manufacturer.

However, a charge timer should be included for safety.

The charge cannot be terminated on a voltage. The capacity reached at 4.2 Volts per cell is only 40 to 70% of full capacity unless charged very slowly. For this reason you need to continue to charge until the current drops, and to terminate on the low current.

It is important to note that trickle charging is not acceptable for lithium batteries. The Li-ion chemistry cannot accept an overcharge without causing damage to the cell, possibly plating out lithium metal and becoming hazardous.


http://www.powerstream.com/li.htm
(Emphasis added)

Read through slowly and carefully, with attention to the diagrams, this may help:
http://lygte-info.dk/review/Review%20Charger%20Xtar%20VC2%20UK.html

And on this page
http://lygte-info.dk/info/How%20do%20I%20test%20a%20charger%20UK.html
Look at the diagram labeled

Quote:
This is the way a LiIon charge curve is supposed to look. The current is constant until the battery reach 4.2 volt, then it will slowly drops while the voltage stays at 4.2 volt.

Look back at that first link, the last bit I boldfaced.
That bit about becoming hazardous — know what lithium plating out means?
You can look it up: https://www.google.com/search?q=li-ion+plating+out+lithium

As the guy says in the movie: Do you feel lucky? Well, do ya?

Don’t forget — this stuff isn’t consumer-grade technology, lithium-ion cells are definitely not ready for prime time.
The chemistry isn’t fully understood — the problem of metallic lithium plating out from overcharging, for example, is still news right now:
http://www.sciencedaily.com/releases/2014/09/140903105638.htm

Bort
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I was about to say welcome to my world, none of the chargers i have bought so far can get to 4.2V but your setup sounds crazy all around.

The Journal of Alternative Facts TM

"It is critical that there is a credible academic source for the growing and important discipline of alternative facts. This field of study will just keep winning, and we knew that all the best people would want to be on board. There is a real risk in the world today that people might be getting their information about science from actual scientists"

 

 

 

RMM
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zoom zoom wrote:

My other charger is a cheap one, generic 2 battery charger, and the batteries consistently come off it reading 4.3-4.4V. The XTAR is giving me different results with each battery, some come off as low as 4.13V, while most are 4.14, some get up to 4.17, and ONE battery was at 4.18V. I've noticed the digital voltmeter also usually jumps to 4.2 prematurely. It will say 4.2, and keep charging for several mAH. I ran one battery down to 2.75V to see what the charger would do with it. It said 4.2V within 30 minutes, and continued to charge for about 16 hours loading the remaining 2200 mAH for a total of 2758 mAH in a battery that is supposed to  be rated at 2400mAH. When I took it off charge, it only read 4.17 with the voltmeter. I stuck it on my old charger and it continued to charge for 3 hours and came off at 4.23V.

Your batteries are probably toast if you've been charging them to 4.3-4.4V.  Cells that are damaged will have higher internal resistance, and will take much longer to terminate once in constant voltage mode.  The total mAh means that's how much energy was put into the battery, but the battery's internal resistance will eat the rest of the energy.  So if a 2200mAh battery is takes 2758mAh worth of energy it probably has a lot of internal resistance.  

Most of the energy is put into the battery in the constant current phase (70%-80%), then the constant voltage phase tops them off at a much slower rate.  That is how it is supposed to work, but if your cell has a lot of internal resistance (damaged) it will have a hard time getting to the constant voltage termination point.

If a battery charged at 16 hours after hitting 4.2v, that battery is toast.  Period.

Mountain Electronics : batteries, Noctigon, and much more! What's new? 

zoom zoom
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I'm really sorry I typo'd and meant that my old charger consistently charged to 4.23/4.24V not 4.3-4.4. 

 

The batteries do drop a little voltage over a 12 hour period, usually not more than .02V.

 

 

I would almost think it could be bad batteries, but I have 4 different types of 18650's, some from a laptop battery pack FS thread here, in which another member bought some, charged and checked them, and was reselling as good batteries. I can't believe the batteries are at fault if he was getting some from the same lot to charge to full capacity and stay that way.

 

 

If a battery charged at 16 hours after hitting 4.2v, that battery is toast.  Period.


The VC2 charger said it was @ 4.2V, when I pulledif off after the charger said it was fully charged my voltmeter said it was @ 4.17V, I put it on my old charger, charged for about 3 hours and my voltmeter read 4.23V.

Halo...
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Termination voltage will vary. Exactly 4.20v is never guaranteed.

Do note that li-ions are suppose to spend some time time charging at 4.2 (or whatever the termination voltage is). That is the constant voltage (cv) phase. Old, worn, damaged batteries can spend longer in cv phase.

Quote:

The 2600mAh battery has a very long CV phase, probably because it is getting old.

[…]

The charger has no problem with my old IMR cell.

When the green line starts dropping that is the cv phase. You can see the old 16340 IMR spends most of its time in the cv.






zoom zoom wrote:
I ran one battery down to 2.75V to see what the charger would do with it. It said 4.2V within 30 minutes, and continued to charge for about 16 hours loading the remaining 2200 mAH for a total of 2758 mAH in a battery that is supposed to  be rated at 2400mAH. When I took it off charge, it only read 4.17 with the voltmeter. I stuck it on my old charger and it continued to charge for 3 hours and came off at 4.23V.

This battery sounds old or damaged.
Essexman
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How good is your DMM? When was it last calibrated? What amb temp are you working at?

I don’t want you to answer the above questions, just trying to point out that there are so many things that can effect a Voltage reading.

zoom zoom
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I'm getting the hint that you guys are pointing out CV charge phase is done at 4.2V, what I don't understand is why a fresh off the charger battery only reads 4.13-4.17V with my voltmeter. 

 

There is about a 20 minute difference in runtimes with using (the same Sanyo 2600mAH battery) my old charger vs using the VC2. If my oLD charger is slightly overcharging the batteries (IF that's the case..?) I'll buy another cheap charger that will hopefully overcharge them the same (up to 4.24V) and use it instead. I don't care about the degradation of the battery, if it explodes or catches on fire. It's never anywhere that will do any damage except my hand while its in the flashlight, and I have over 100 batteries I can burn through. I charge the batteries at work, plugged into a GFCI surge strip plugged into a GFCI outlet ran off a 20A breaker bolted to a steel wall with no paint in a room made of 1/4"-1/8" steel.........on a barge in the middle of the river! Literally I don't think it could be much safer an environment for charging a battery, let it burn!

 

i had to let one of my flashlights run for about 26 hours to get the battery discharged to that point, used it since it does as good as the rest. I have a bunch but I've only been messing with about a dozen the last week or so.

Halo...
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zoom zoom wrote:
The VC2 charger said it was 4.2V, when I pulledif off after the charger said it was fully charged my voltmeter said it was 4.17V, I put it on my old charger, charged for about 3 hours and my voltmeter read 4.23V.

As soon as a charger ends the voltage can drop, particularly with worn batteries. Look at the voltage line on the charts I posted. It drops right at the end of charge (yellow vertical line). When you overcharge, as your old charger does, it can drop less or mask the drop.

4.17v is perfectly fine. Again, exactly 4.20 is not guaranteed by any chargers specs. Much better 0.03v under than over.

zoom zoom
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Halo... wrote:
zoom zoom wrote:
The VC2 charger said it was @ 4.2V, when I pulledif off after the charger said it was fully charged my voltmeter said it was @ 4.17V, I put it on my old charger, charged for about 3 hours and my voltmeter read 4.23V.
As soon as a charger ends the voltage can drop, particularly with worn batteries. Look at the voltage line on the charts I posted. It drops right at the end of charge (yellow vertical line). When you overcharge, as your old charger does, it can drop less or mask the drop.

 

 

gotcha Smile 

hank
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Quote:
I don’t care about the degradation of the battery, if it explodes or catches on fire. It’s never anywhere that will do any damage

Just to make sure: you know not to inhale, and why, and for how long, when your toast finally catches on fire?