# New XTAR WP2 II Li-ion charger



## gopajti (Aug 8, 2011)

*Features:*
XTAR WP2 charger is apply to charging for two 14500/ 14650/ 17670/ 18500/ 18650/ 18700 3.7V Li-ion battery simultaneously but independently, it can charge for 10440/16340 when use 2pcs spacers. It is designed with undervoltage lockout and algorithm (TC.CC.CV) charging method which can monitor the battery's status real time and control charging safe automatically. 
WP2 designed with USB output function, use fully charged battery can supply electricity to those devices power below 5.0V/500mA.
WP2 Charger adopts reverse-polarity protection circuit board and over/under voltage disconnecting technology, can prevent the possibility like sundries, wrong polarity and misoperation caused short circuit. 
WP2 built battery over discharging activating function, it can repair varying degrees discharged battery and then charging automatically, it is your first choice safer and reliable Li-ion battery charger.

more info qualitychinagoods


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## gopajti (Aug 26, 2011)

I received today from qualitychinagoods good build quality, I think this is one of the best "low-budget" li-ion charger

switch
0 - USB 5.0V/500mA
1 - 500mA
2 - 1000mA

pics, details


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## old4570 (Sep 1, 2011)

Nice pictures : 

Charges @ 1A and 500mAh - 3 position switch at the front ... 
0 position is for the USB charge function 
1 Position is for 500mAh charge rate 
2 position is for the 1A charge position 

So far seems to perform solidly , still testing .. But looks good .. 

Did I mention those are some nice pictures ? What is the termination voltage range on that one ? If one may ask ...


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## jasonck08 (Sep 1, 2011)

Cool I'll be interested to see if the circuit has the same problem as with the V1 that causes the voltage and current to constantly spike up and down. I observed the same behavior in other Li-ion charge IC's when they are overheating.


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## gopajti (Sep 1, 2011)

fully charged Jetbeam 18650


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## HKJ (Sep 1, 2011)

jasonck08 said:


> Cool I'll be interested to see if the circuit has the same problem as with the V1 that causes the voltage and current to constantly spike up and down. I observed the same behavior in other Li-ion charge IC's when they are overheating.


 
I have not seen that problem on WP2, but it does turn off the charge current each second to check cell voltage.


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## jasonck08 (Sep 1, 2011)

HKJ said:


> I have not seen that problem on WP2, but it does turn off the charge current each second to check cell voltage.



How do you know its turning off the charge current every second to check voltage? That's definitely not proper behavior of any Li-ion charging IC I've ever heard of... I'm more inclined to think that the IC is in thermal limiting mode and overheating, thus reducing the current to pulses to avoid frying the IC. When i measured the current a while back I constantly saw spikes form 100mA to 500mA.


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## Be-Seen Triker (Sep 1, 2011)

jasonck08 said:


> How do you know its turning off the charge current every second to check voltage? That's definitely not proper behavior of any Li-ion charging IC I've ever heard of... I'm more inclined to think that the IC is in thermal limiting mode and overheating, thus reducing the current to pulses to avoid frying the IC. When i measured the current a while back I constantly saw spikes form 100mA to 500mA.


 
My Ultrafire WF-188 does this same pulse mode charging. I'm using the 300ma charge rate.


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## 45/70 (Sep 1, 2011)

*EDIT:* Posted in the wrong thread, but nice pics, gopati!

Dave


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## HKJ (Sep 2, 2011)

jasonck08 said:


> How do you know its turning off the charge current every second to check voltage? That's definitely not proper behavior of any Li-ion charging IC I've ever heard of... I'm more inclined to think that the IC is in thermal limiting mode and overheating, thus reducing the current to pulses to avoid frying the IC. When i measured the current a while back I constantly saw spikes form 100mA to 500mA.


 
With a oscilloscope connected to the charger it is easy to see. This "turning off to measure voltage" is very common behaviour on LiIon chargers, it has nothing to do with overheating.


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## jasonck08 (Sep 2, 2011)

Be-Seen Triker said:


> My Ultrafire WF-188 does this same pulse mode charging. I'm using the 300ma charge rate.





HKJ said:


> With a oscilloscope connected to the charger it is easy to see. This "turning off to measure voltage" is very common behaviour on LiIon chargers, it has nothing to do with overheating.



Ultrafire is a very low quality charger with only a constant current charge method. This charger claims to have a CC/CV charge profile, and as far as I am aware, this is only achievable by the use of a Li-ion charging IC. No Li-ion charging IC i've seen should exhibit this type of behavior of measuring the voltage every 1 second, and decreasing the voltage and current as a result.

HKJ, have you logged the average charge current of the charger? I've only done 5 minutes worth of testing with the WP2, and I observed pulses of 100mA to 500mA constantly. Your charging graphs look somewhat similar to my initial testing of the LTC-4054-4.2 when the IC was overheating. It would do about the same thing, pulse for about 1 second then stop then pulse again. This only happened however during the CC stage, because there is far less heat dissipated through the IC during the CV stage.
















The pulsing and noise is quite similar. Can anyone point out what type of main chips they are using on the PCB?


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## HKJ (Sep 2, 2011)

jasonck08 said:


> Ultrafire is a very low quality charger with only a constant current charge method. This charger claims to have a CC/CV charge profile, and as far as I am aware, this is only achievable by the use of a Li-ion charging IC. No Li-ion charging IC i've seen should exhibit this type of behavior of measuring the voltage every 1 second, and decreasing the voltage and current as a result.



You can easily make a LiIon charger with a small microprocessor controlling a smps. I believe that I have seen this packed into a single IC.




jasonck08 said:


> HKJ, have you logged the average charge current of the charger? I've only done 5 minutes worth of testing with the WP2, and I observed pulses of 100mA to 500mA constantly. Your charging graphs look somewhat similar to my initial testing of the LTC-4054-4.2 when the IC was overheating. It would do about the same thing, pulse for about 1 second then stop then pulse again. This only happened however during the CC stage, because there is far less heat dissipated through the IC during the CV stage.
> 
> The pulsing and noise is quite similar. Can anyone point out what type of main chips they are using on the PCB?



I have not been running a average (not anymore than my meters are doing), but I have used an oscilloscope to see the current pulses, they do not look like any overheating shutdown.
The chip used is not a LTC-4054 or any of the derivates, that chip uses linear regulation and this charger does not use linear regulation (The 62 Khz frequency in the current shows this).


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## shadowjk (Sep 2, 2011)

Measuring the voltage during OFF pulse would measure something that's closer to OCV, which isn't what you're aiming for when you're charging Li-Ion...


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## HKJ (Sep 2, 2011)

shadowjk said:


> Measuring the voltage during OFF pulse would measure something that's closer to OCV, which isn't what you're aiming for when you're charging Li-Ion...


 
You are not measuring the rest voltage, but the actual voltage at the chemistry, eliminating all resistance. As you can see on my graph the voltage will drop a bit, when charging is stopped.
But as you also can see from the graph the charger never goes above 4.2 volt, even when charging.


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## shadowjk (Sep 2, 2011)

The CC/CV algorithm uses the voltage during charge, not voltage at 0 current, so I don't know what use there'd be to cycle current on/off, except that if you measure both voltages you can work out the internal resistance of the cell + circuit/lead resistances...


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## jasonck08 (Sep 2, 2011)

I agree the measuring of the cell voltage every second is not really what the CC/CV algorithm calls for. This pulsing / noise whether intentional or not is a design flaw in the unit IMO.


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## Mr Happy (Sep 2, 2011)

It's really OK to use some different algorithm than CC/CV. CC/CV not a prescribed rule that you must follow lest terrible things happen to you.

As HKJ explains above, there are prescribed limits on the charging of the cell that must be satisfied: you should not exceed the maximum voltage (4.2 V) and you should not exceed the maximum charging current (e.g. 0.8C). Within those limits there are a whole variety of charging algorithms that could be used, and for various reasons some of them could be a better engineering choice than others. They are not wrong, merely different.

It happens that a pure CC/CV algorithm will charge a cell to completion in the shortest time compared to any other algorithm. If that is your goal, then a pure implementation of CC/CV is good. However, if you perhaps want an efficient charger, a small charger, a light charger, or an economical charger, then charging as fast as possible may not be the goal that drives your design decisions. Good engineering as about making the right decisions for the right reasons. Blindly following rules because they are engraved on a stone tablet is never a good basis for design.

HKJ has tested this charger and analyzed it carefully. The analysis shows it is charging safely and respecting the prescribed limits of the cells. Therefore the design is perfectly satisfactory and it is not defective at all.


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## jasonck08 (Sep 2, 2011)

@ Mr happy, true that the charger may not be damaging to cells, and probably works just fine, however the two things I have a problem with are:

1) Claims to be a CC/CV, but it's not really.

2) Claims 500mA / 1000mA charge current, but with constant pulses from ~100mA to 500 or 1000mA, its clearly not charging at those currents.


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## Mr Happy (Sep 2, 2011)

jasonck08 said:


> @ Mr happy, true that the charger may not be damaging to cells, and probably works just fine, however the two things I have a problem with are:
> 
> 1) Claims to be a CC/CV, but it's not really.
> 
> 2) Claims 500mA / 1000mA charge current, but with constant pulses from ~100mA to 500 or 1000mA, its clearly not charging at those currents.


From an examination of the review measurements provided by more than one reviewer here, those claims seem close enough to me. I would be very happy to own and use the charger. (I come at this with a technical background and therefore some appreciation of the design choices faced by the designers of the charger. I think the demand for pure CC/CV behavior with perfectly smooth lines on the graphs would result in a different charger from the one you see--a charger that would likely be bigger, heavier, more expensive, hotter in operation and unlikely really to offer much practical benefit for those differences. I want the charger reviewed here, not the ideal CC/CV charger of theory.)


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## HKJ (Sep 3, 2011)

jasonck08 said:


> @ Mr happy, true that the charger may not be damaging to cells, and probably works just fine, however the two things I have a problem with are:
> 
> 1) Claims to be a CC/CV, but it's not really.



As you can on the curves in my review it is close to a CC/CV charger.




jasonck08 said:


> 2) Claims 500mA / 1000mA charge current, but with constant pulses from ~100mA to 500 or 1000mA, its clearly not charging at those currents.



My measurements does not show that, it shows 500 mA / 1000 mA with short breaks to measure the voltage. Please provide some oscilloscope traces showing the swing between 100mA and 500 mA current. A typical DMM is not fast enough to show the off pulses and will show some random value between the charge current and some lower value (could be 100mA, but it depends on the DMM).


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## 45/70 (Sep 4, 2011)

Mr Happy said:


> It's really OK to use some different algorithm than CC/CV. CC/CV not a prescribed rule that you must follow lest terrible things happen to you.
> 
> As HKJ explains above, there are prescribed limits on the charging of the cell that must be satisfied: you should not exceed the maximum voltage (4.2 V) and you should not exceed the maximum charging current (e.g. 0.8C). Within those limits there are a whole variety of charging algorithms that could be used, and for various reasons some of them could be a better engineering choice than others. They are not wrong, merely different.



I agree that it is possible to charge Li-Ion cells without adhering to the manufacturer's recommendations. Most available "consumer type" chargers do just that.

As for the "prescribed limits on the charging of" Li-Ion cells, your statement(s) are correct. At the same time however, I am not aware of any Li-Ion cell manufacturer that recommends, or suggests using a CC/CV algorithm as a guideline for charging their cells, rather all that I am aware of state that a CC/CV algorithm must be used.



> Good engineering as about making the right decisions for the right reasons. Blindly following rules because they are engraved on a stone tablet is never a good basis for design.


This is fine, but when this includes deviating from the manufacturer's prescribed charging method, even as a hobbyist, I have trouble supporting this viewpoint.



> I want the charger reviewed here, not the ideal CC/CV charger of theory.)


I'd still rather have one that follows the manufacturer's recommendation.

Dave


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## jasonck08 (Sep 5, 2011)

45/70 said:


> I agree that it is possible to charge Li-Ion cells without adhering to the manufacturer's recommendations. Most available "consumer type" chargers do just that.
> 
> As for the "prescribed limits on the charging of" Li-Ion cells, your statement(s) are correct. At the same time however, I am not aware of any Li-Ion cell manufacturer that recommends, or suggests using a CC/CV algorithm as a guideline for charging their cells, rather all that I am aware of state that a CC/CV algorithm must be used.
> 
> ...



Well said, couldn't agree more! I too wouldn't call CC/CV a guideline, but more of a requirement for a quality charger and for keeping cells healthy. 



Mr Happy said:


> It's really OK to use some different algorithm than CC/CV.



All well known manufacturers say use a CC/CV charging method, then also provide a graph for what the charging method should look like when its data logged. I don't know any cell manufacturer that states using another method is acceptable.



HKJ said:


> As you can on the curves in my review it is close to a CC/CV charger.
> My measurements does not show that, it shows 500 mA / 1000 mA with short breaks to measure the voltage. Please provide some oscilloscope traces showing the swing between 100mA and 500 mA current. A typical DMM is not fast enough to show the off pulses and will show some random value between the charge current and some lower value (could be 100mA, but it depends on the DMM).



I observed the pulses of current with my Fluke 179 and my higher end Agilent meter. If I cared enough I suppose I could data log the current during the charging process. I can pretty much guarantee that its not going to be charging at the stated 500/1000mA due to the frequent pulses of lower currents. I don't have the luxury to own a scope.

While its much closer than the majority of the chargers on the market we see, its still not the really CC/CV. Show that graph to an engineer from Panasonic or Sanyo they will laugh and tell the designer to go back to the drawing board.

There is a constant current mode, but no constant voltage, and then if you take into consideration the whole pulse charging thing or noise in the charging, this charger is only about 40% of the way there towards a true CC/CV charger IMO.


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## HKJ (Sep 5, 2011)

jasonck08 said:


> Well said, couldn't agree more! I too wouldn't call CC/CV a guideline, but more of a requirement for a quality charger and for keeping cells healthy.



I do simply not buy this (Except if you can get somebody from a large battery manufacturer to say it damages the battery). The pulsing charger does not do anything outside the CC/CV charging enelope. 




jasonck08 said:


> All well known manufacturers say use a CC/CV charging method, then also provide a graph for what the charging method should look like when its data logged. I don't know any cell manufacturer that states using another method is acceptable.



That is the easy way to specify a charging algorithm and will probably also be the fastest, why would the manufacturer specify anything else?



jasonck08 said:


> I observed the pulses of current with my Fluke 179 and my higher end Agilent meter. If I cared enough I suppose I could data log the current during the charging process. I can pretty much guarantee that its not going to be charging at the stated 500/1000mA due to the frequent pulses of lower currents. I don't have the luxury to own a scope.
> 
> While its much closer than the majority of the chargers on the market we see, its still not the really CC/CV. Show that graph to an engineer from Panasonic or Sanyo they will laugh and tell the designer to go back to the drawing board.
> 
> There is a constant current mode, but no constant voltage, and then if you take into consideration the whole pulse charging thing or noise in the charging, this charger is only about 40% of the way there towards a true CC/CV charger IMO.



Most DMM is a bit slow, at least mine is and cannot really be used to measure pulsing current, as you can see in my logging I do never record a 0 value, even though there is one each second (The meter I is the top Fluke DMM). With the scope I can easily see the 0.5 and 1A charging current and the average may be 5 to 10 % low due to the pulsing or maybe not (the current is a bit above 0.5 A on the scope, maybe this compensates for the pulsing). I have not tried to measure the exact average charge current (This is possible with my meters).

Would I prefer a real CC/CV charger? The answer is yes, but I do not believe that the difference between this charger and a real CC/CV is large in practical use.


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## jonnyfgroove (Sep 5, 2011)

Do you guys think it would be worthwhile to replace my Ultrafire WF-139 with one of these in regards to cell health/longevity? All my Li-Ions are the AW brand.


ETA: Thanks for answering my question, I'm going to order one. :thumbsup:


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## 45/70 (Sep 5, 2011)

jonnyfgroove said:


> Do you guys think it would be worthwhile to replace my Ultrafire WF-139 with one of these in regards to cell health/longevity? All my Li-Ions are the AW brand.



Without a doubt, the Xtar charger is a better charger than the WF-139. The WF-139 is IMO, one of the worst chargers available. The QC is hit and miss, and at best they are only a "so so" charger, that doesn't follow the recommended charging algorithm, at all. They are basically just a constant current (CC) charger.

Dave


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## scottyhazzard (Sep 6, 2011)

I am a bit confused. The discussion seams to straddle the fence between semantics and science. Both valid topics for discussion but I can't keep up with the science part. I have the WF 139 and I am replacing it to protect my investment in batteries. I was under the impression that within the limits of my budget, the Xtar WP2 II was safer and not likely to over-charge my 18650's. I have one in the mail now, is it safe to use on by batteries or will it shorten their lives?


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## HKJ (Sep 6, 2011)

scottyhazzard said:


> I have one in the mail now, is it safe to use on by batteries or will it shorten their lives?



It is one of the best cradle chargers, only the 4Sevens has a better charge curve of the chargers I have tested.


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## scottyhazzard (Sep 6, 2011)

Thanks, HKJ. Much appreciated.


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## Mass. Wine Guy (Sep 13, 2011)

I know next to nothing about the technology, but I want to buy a 2600 mah 18650 battery for an MG P-Rocket Cree XP-G R5 flashlight I want to buy.

Does this charger do the job well? How long does it take to charge a 18650?

Thanks.


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## Be-Seen Triker (Sep 13, 2011)

I just received this charger a several days ago and have given it a good workout. The end voltage of most cells are between 4.15-4.17V which is consistent with what others have reported. This is true with 18650 Callies Kustom 3100 cells, XTAR 2600mah cells , and unprotected Panasonic CGR18650D 2350mah cells. The "CV" part of the charge take quite a while. I think in every instance, with maybe a 20% discharge, the charge cycle is always over an hour. The charger stays quite cool. I am sure that most of this charge period is topping off the cell (the CV part of the cycle).

Out of a half dozen chargers I have, this is by far the most consistent and reliable one to date.
My previous go-to charger was the modified UF WF-188 which would terminate my BRC3000 cells at 4.22V. Indeed, it was CC only as it drew 300ma thoughout the charge cycle. Needless to say, I am much more comfortable with the new XTAR WP2 II than with the WF-188. The WP2 II has terminated on its own consistenly through at least 50 cycles of various cells.

Could someone come up with a true CC/CV charger which could also be adjusted for the recommended charge rate per the cell manufacturer's specifications for $20? ...I once looked at lab supplies for manual control. Ouch!


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## Acid87 (Sep 13, 2011)

Seems pretty good. I was about to buy a 4sevens single bay but might just pop on this. I assume you can charge rcr123's with a spacer?


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## RI Chevy (Sep 13, 2011)

*How long does it take to charge a 18650?*

Depends on the charger (maH/Voltage, etc.) For a 3100 maH cell, it usually trips off somewhere around 4 1/2 to 5 hours at 700maH charger. Depends on the state of the cell. There are a lot of variables that determine how long it will take.


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## Be-Seen Triker (Sep 13, 2011)

Acid87 said:


> Seems pretty good. I was about to buy a 4sevens single bay but might just pop on this. I assume you can charge rcr123's with a spacer?


 
You will need a spacer which is not supplied. One thing to note from the 4sevens is that the XTAR only does 4.2V... it doesn't have the 3.6V option.


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## Mass. Wine Guy (Sep 13, 2011)

— "The end voltage of most cells are between 4.15-4.17V which is consistent with what others have reported."

What does this mean in English? End voltage?


"The "CV" part of the charge take quite a while."

What's the CV part?

So will it charge a 2600 mah 18650 battery in about four hours to a really good, full charge?


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## Be-Seen Triker (Sep 13, 2011)

Just to remind everyone, this is the published manufacturer's "Charge Condition" for the published specification (Panasonic NCR18650).







This should provide some hint to how long a cell takes to charge.


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## tony22 (Sep 13, 2011)

Be-Seen Triker said:


> You will need a spacer which is not supplied. One thing to note from the 4sevens is that the XTAR only does 4.2V... it doesn't have the 3.6V option.



Hmm, that's troubling. I thought in HKJ's review that he said it came with the spacers. I just oredred one and figured it would be supplied with them. Maybe I confused this with another of his reviews.


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## Be-Seen Triker (Sep 13, 2011)

Others have expressed the same. The manual talks about spacers but they have not been included for anyone that I've seen.

Maybe a stack of pennies would suffice.


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## HKJ (Sep 14, 2011)

tony22 said:


> Hmm, that's troubling. I thought in HKJ's review that he said it came with the spacers. I just oredred one and figured it would be supplied with them. Maybe I confused this with another of his reviews.


 
The only thing I wrote about spacers is that they are needed for CR123. Only *M*P2 and WP6 did included spacers.


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## scottyhazzard (Sep 14, 2011)

Mine came with a pair of screw-in spacers. I only have experience charging my Callie's 18650s and some cheepo trustfire 14500. The trustfires get HOT. I would imagine you could charge a single 123 at a time using the spacers provided but I don't know.


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## 45/70 (Sep 14, 2011)

scottyhazzard said:


> ......and some cheepo trustfire 14500. The trustfires get HOT.



You should consider disposing of/recycling those cells. Li-Ion cells should never get "hot" when charging. Older cells may warm slightly, but if they actually get "hot" I would guess the IR of your cells is well beyond acceptable limits. Their performance is likely poor, as well. My experience with ~2 year old TrustFire protected and unprotected 14500 cells has shown that they are not worth bothering with at any price.

Dave


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## Lightfoot98 (Sep 14, 2011)

I recieved the WP2-II a few days ago and ran several cells thru it to check function and to determine cut-off voltage.
It consistently charged to 4.20 and held it there in CV untill cut-off. That is on both bays.
Checked at 500ma and 1000ma.
All my cells came hot off the charger at 4.18 as soon as charger terminated.

Mine came with 2 spacers.

I really like this charger.


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## tony22 (Sep 14, 2011)

Well, now I'm confused. I just got mine and it looks like I got no spacers - but I did get the 12V adapter! Is it obvious in the WP2 box where the spacers are located?

If I really didn't get them, what spacers do I need to buy for RCR123 batteries?


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## Be-Seen Triker (Sep 14, 2011)

Lightfoot98 said:


> ...
> Mine came with 2 spacers.
> ...


 
Sounds like an early packaging issue where spacers were inadvertently left out.


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## tony22 (Sep 14, 2011)

Can someone post a pic of what the supplied spacers look like? I'd like to email that to the retailer where I got mine to see if he could track them down. Given the iffy nature of actually getting them in the package I'm not sure I want to risk a return in the hopes the next one will have them.


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## scottyhazzard (Sep 14, 2011)

Thanks 45/70. I can't afford a fire.

I will try posting photos of my Xtar from SBFlashlights.

Spacers in... Spacers are at top of battery bays-






Spacers out... 





I hope this helps, tony22


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## tony22 (Sep 14, 2011)

Thank you Scotty!!!


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## tony22 (Sep 15, 2011)

FYI the seller confirmed that the earlier batch (1 month old!) did not have the spacers but the recent batch he received did. He said he would take care of things by sending one out.


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## tony22 (Sep 18, 2011)

I should have my spacers by tomorrow. It hadn't occurred to me until now to ask about the best way to get my new RCRs going. Since the WP2 II doesn't seem to do any sort of fancy discharge-charge routine, is it better to use the new cells until they run down, or top them off on the charger before first use?


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## 45/70 (Sep 18, 2011)

tony22 said:


> ......It hadn't occurred to me until now to ask about the best way to get my new RCRs going. Since the WP2 II doesn't seem to do any sort of fancy discharge-charge routine, is it better to use the new cells until they run down, or top them off on the charger before first use?



Hi Tony. The only time you would charge/discharge Li-Ion cells, is when you want to check their capacity. Otherwise, there is no benefit to doing this to Li-Ion cells, it just wears them out.

As for your new cells, I would charge them up first. Unlike other types of cells, Li-Ions prefer shallow, rather than deep discharges. Avoiding deep discharging your cells can extend cycle life considerably.

Another difference between Li-Ions and other types of cells, is there is no drawback to "topping off" cells often. The only time you might want to avoid doing this, is when you are not going to use the cell(s) for a while. In this case, it's best if you store cells at about a 40% state of charge level. This prevents the more rapid internal degradation that occurs when cells are at or near maximum charge level, and at the same time, prevents any possibility of the cell self discharging to a damaging low voltage, if for example, you were to end up storing them longer than planned.

Dave


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## tony22 (Sep 19, 2011)

Thanks for the awesome details Dave.


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## tony22 (Sep 20, 2011)

Got my spacers (does the charger come with only two?). Charged my first RCR123 and pulled it when the light turned green. I'm not sure if I should be a little disappointed. The voltage from my Fluke DMM read 4.15 volts. That seems a bit low if a RCR is supposed to come in at 4.20. Or is it?

I used the 500 mA setting.

Hmm, I put the nubbins on the other charging space and popped the batteries in there. It went red then after a short while green. I got 4.17 volts there. Is that more because of a bit of "rebound" charging or is it possible the second space charges it up a bit more?


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## Mr Happy (Sep 20, 2011)

tony22 said:


> Or is it?


No, not so. If a battery came off the charger at 4.20 V the charger would not be working properly. The only way to get a battery up to 4.20 V without waiting forever is to raise the charging voltage above 4.20 V, which the charger is not supposed to do.


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## tony22 (Sep 20, 2011)

Mr Happy said:


> No, not so. If a battery came off the charger at 4.20 V the charger would not be working properly. The only way to get a battery up to 4.20 V without waiting forever is to raise the charging voltage above 4.20 V, which the charger is not supposed to do.



Ah. So what's the minimum acceptable voltage for a properly charged RCR123?


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## Mr Happy (Sep 21, 2011)

tony22 said:


> Ah. So what's the minimum acceptable voltage for a properly charged RCR123?


That really depends on many things. But most people would consider 4.15 V and upwards to be acceptable.


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## tony22 (Sep 21, 2011)

I guess I'm okay then. Appreciate the info.


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## 45/70 (Sep 21, 2011)

Tony, keep in mind that a LiCo cell with an OC voltage of 4.15 Volts translates to roughly a 95% charge. Also keep in mind that 4.20 Volts is the _maximum allowable voltage_ for LiCo and LiMn cells. However, this figure is actually stated as 4.20 Volts +/- 0.05 Volt (or +/- 1%), so either way, your cell is in spec.

Cells charged at a higher rate (in proportion to the cell's capacity) will not charge as fully as cells charged at a lower rate. This is why an 18650 cell will normally come off the charger at a higher voltage than a 16340 cell, when charged at the same current rate. This assumes that the two cells are of the same type, age, and condition. The older, or more used a Li-Ion cell is, the lower the charged voltage will be.

This voltage variance is common, when using a charger that utilizes a proper CC/CV charging algorithm, which the XTAR imitates fairly closely. Many cheapo chargers will actually always charge cells of different sizes, ages, and capacities to the same voltage. These chargers damage the cells in the process, as they are actually overcharging the cells.

Dave


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## jasonck08 (Sep 22, 2011)

Mr Happy said:


> No, not so. If a battery came off the charger at 4.20 V the charger would not be working properly. The only way to get a battery up to 4.20 V without waiting forever is to raise the charging voltage above 4.20 V, which the charger is not supposed to do.



The final charge voltage has to do a lot with the termination current. For example a 100mA termination current may leave the cell at 4.15v, while a 50mA termination might terminate at 4.18v.


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## FreeMagenta (Sep 25, 2011)

Hello I am charging TF 2400 "Flames" in my WP2, and with each cycle the after cutoff voltage goes higher. Just now, it looks like this: http://www.youtube.com/watch?v=wtJaMhcahNo (Cutoff about 4:50) 
Battery voltage just after cutoff 4,19, drops to 4,18 in 2-3 minutes and stays there for 6 hours. First cycles were about 4.15... I am measuring the battery voltage after each charging, and it always goes by few milivolts up. From 4.15 top 4.19V with each cycle. 
Shall I be worried?...


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## Be-Seen Triker (Sep 25, 2011)

You do not need to worry... yet.

Here is an interesting read:
http://industrial.panasonic.com/www-data/pdf/ACA4000/ACA4000PE4.pdf


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## tony22 (Sep 25, 2011)

FreeMagenta said:


> Hello I am charging TF 2400 "Flames" in my WP2, and with each cycle the after cutoff voltage goes higher. Just now, it looks like this: http://www.youtube.com/watch?v=wtJaMhcahNo (Cutoff about 4:50)
> Battery voltage just after cutoff 4,19, drops to 4,18 in 2-3 minutes and stays there for 6 hours. First cycles were about 4.15... I am measuring the battery voltage after each charging, and it always goes by few milivolts up. From 4.15 top 4.19V with each cycle.
> Shall I be worried?...



FreeMagenta, are you letting the battery discharge before cycling it again?


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## FreeMagenta (Sep 26, 2011)

tony22 said:


> FreeMagenta, are you letting the battery discharge before cycling it again?


 
As I wrote in video description, about 2 times the baterry was discharged to 3.6V (3rd anr 4th cycle), 8 times to around 3.8V.


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## carto.gr (Sep 29, 2011)

thanks for the infos
i saw several wp2 II chargers in chinese sites but with different prices.
are there several qualities for that charger or what?

greets
carto.gr


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