# Review of / Measurement on Xtar WP6 II charger



## HKJ (May 24, 2011)

[SIZE=+3]Charger Xtar WP6 II[/SIZE]










This charger was introduced in 2010 and updated in 2011 to the II version. It has 6 channels, i.e. it can do 6 cells independently of each other. The new version of the charger is using another charging algorithm and includes spacers that can be mounted on the plus connection.













The charger is powered from a single 12 volt DC connector, this connector can be powered from either the supplied AC adapter or from a car adapter. The AC adapter I got is a universal voltage adapter (100 - 240 VAC 50/60 Hz) with a plug for European use.
There is a led for each channel, this led will be red when the charger is charging and green at all other times.









The charger is supplied with spacers that can be mounted on the plus terminal on the charger. Because the spring in the charger is longer than a spacer, it is possible to adapt the charger for any cell that is below 70mm in length.
























The charger can handle 70 mm long batteries, including flat top cells.



[SIZE=+2]Measurements[/SIZE]

Below 1.5 volt the charger does not charge, it discharges with a less that 4 uA.
Between 1.5 and 2.8 volt the charger charges with about 100 mA.
Between 2.8 volt and 4.2 volt the charger is applying regular charge current (See curve below).
When the charge current goes below 150mA the charging is stopped and it will discharges with < 10 uA.
The charger will not restart charging before the battery has been removed or the voltage goes below 1.5 volt.
When charger is disconnected from power, but with a battery in, it will draw below 300uA from the battery.
The channels works in pairs, when using both channels in a pair, the charge current is doubled, but only applied half the time.
The charger switch to dual channel when it needs to charge on both channel, when one battery is full it switches back to single channel mode.






The charge curve looks like a CC/CV charger, and it stops at a rather high charge current. This is not a real problem because the charger measures the voltage with charge current turned off, this means that the charging is not a real CC/CV charging, and the batteries is filled completely, even when the current is turned off at 150mA.






Same battery, but on another channel. There is a good match between the channels.






Same battery, and also using the adjacent channel for another battery, the current is doubled, but only applied half the time, i.e. on average same charging current. This increases the charge time!






A new LiIon cell with a low internal resistance and marked 2400 mAh. It takes 5 hours to charge this cell and with six channel it is possible to charge up to six cells in under 7 hours (3 cells can be done in 5 hours) .






My old 16340 IMR cell. The charge current is just within range for 16340/RCR123 cells (IMR 16340 is no problem, they can be charger at 1.5 ampere).






A closer look on the current shows that the charger stops charging each time it want to measure voltage. This has the advantage that all connection resistance can be ignored and noise from the charger is eliminated. 






The first curve did not show much noise in the charge current, but that was because I used a filter. Without a filter it can be seen that it contains a lot of noise.






With two batteries in adjacent channel the use of double current and only 50% charge time on a channel, can be seen on this scope trace. Current is on in about 2 seconds and off in about 2.3 seconds. Note: This switching between channels cannot be seen on the leds, they show a stable red light while charging.



[SIZE=+2]Conclusion[/SIZE]

The charger has a CC/CV like charge profile, the termination is not according to manufacturer recommendations, but works fine in practice. The support for long 18650 and included spacers makes this charger fine for 18650, 18500, 16340 and 14500 cells. With 6 channels it is possible to get a lot of cells charged in a reasonable time (Two 600 mA channels is faster than one 1200 mA channel when charging two cells). No charging at low voltages might give problems activating a tripped protection.



[SIZE=+3]Notes[/SIZE]

Here is an explanation on how I did the above charge curves: How do I test a charger

The charger was supplied by XTAR for a review.


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## 45/70 (May 24, 2011)

HKJ said:


> The charger has a CC/CV *like* charge profile



Yeah, well. What'd you expect?

Nice job HKJ. That took a lot of work. It's much appreciated.:thumbsup:

The termination at ~150mA isn't too bad for 18650 cells. 0.1C for a 1500mAh cell and close to 0.05C for a 2900mAh cell. Overall, I'd say it's an improvement over the first version anyway.

I don't know why they do it the way they do. I'd still prefer something that worked more like the Pila IBC, or a hobby charger. For the price though, being able to charge six cells at once in a "plug and play" manner, is pretty cool. I still might get one, although the hobby charger works fine. It's just a bit more trouble is all.

Again, nice job there HKJ!

Dave


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## HKJ (May 25, 2011)

45/70 said:


> The termination at ~150mA isn't too bad for 18650 cells. 0.1C for a 1500mAh cell and close to 0.05C for a 2900mAh cell. Overall, I'd say it's an improvement over the first version anyway.



You do not get the point about the way it charges, the cells are filled completely up, because it measures the voltage with the current off.


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## 45/70 (May 25, 2011)

HKJ said:


> You do not get the point about the way it charges, the cells are filled completely up, because it measures the voltage with the current off.



Yeah, you're right, I missed that. Again, I really don't know why XTAR goes about it the way they do, re: my previous comments in other threads as to why they use "voltage checking". Why not just run the proper recommended CC/CV algorithm (which would not require voltage checking)? Supposedly, I'm told anyway, it would be just as easy to manufacture and be much better for the cell(s), as well. Then again, maybe they're attempting to speed up the time it takes to fully charge a cell, as many of the other charger manufacturers do. Unfortunately this deviation from the proper algorithm, comes at the additional expense of risking potential cell damage.:shrug:

Dave


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## shadowjk (May 26, 2011)

Their peculiar charging algorithm might just be a response to the proliferation of people with DMMs measuring the Open Circuit Voltage of batteries AFTER the charger has terminated, seeing it's not 4.2V, and claiming the charger is crap.

If the charger overchargers the cells to have 4.2V OCV, the people with the DMMs will be satisfied. *shrug*


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## 45/70 (May 31, 2011)

HKJ, I was wondering if you had tried charging a 10440, or a 15270 in the WP6 II, as XTAR suggests (from XTAR)?



> * Six independent charging channel for 10440/ 14500/ 14650/ 15270/ 16340/ 17670/ 18650/ 18700 battery.


If so, does the charge current drop due to the IR of such a diminutive cell and more or less go directly to the pseudo CV stage, or is the current applied to the cell in the same manner as for larger cells, making this as scary a proposition (from XTAR) as it sounds?

The charging current initially, appears to not drop at all, with the AW IMR 16340 cell you tested, so it would seem that this would be a bad idea, damaging these smaller size cells, or worse yet, lead to a safety problem. I doubt really though that 600mA through a 300mAh LiCo cell would "vent with flame", at least not for a while, but would certainly shorten cell life considerably. 

I'm still kicking around the idea of getting one of these, shortcomings and all. I don't really need one, as my puny hobby charger will charge 8 cells @ up to ~625mA/cell in parallel, but the "plug and play" convenience of a 6 bay independent channel charger, is appealing. I'm certain I won't be charging any of my 10440, 14250, or 15270 cells with it, but I'm not sure which charger I want to try to get. Which one do you think is better, the WP6, or the WP6 II? I'm guessing the WP6 II, for obvious reasons, but thought I'd ask.

Dave


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## HKJ (May 31, 2011)

The old wp6 is mostly for large capacity cells due to the high termination current, I prefer the new version.
But I will not recommend charging anything with less than 600mAh capacity (and I did not try).


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## 45/70 (Jun 1, 2011)

HKJ said:


> The old wp6 is mostly for large capacity cells due to the high termination current



Thanks, HKJ. As I said, I really don't need one, but the convenience factor is attractive. I would likely only be charging 18650 cells with it (3x and 6x), so the effects of the high termination current and other strange anomalies of these chargers would be lessened, to some degree anyway. I'll review yours, and others reviews on both chargers and think on it a bit more. I would imagine that the WP6 chargers will soon disappear, with the new version out.

Dave


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## LiteTheWay (Jun 1, 2011)

Where can I buy mark 2 version with shipping to Australia?


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## HKJ (Jun 5, 2011)

7histology said:


> Where can I buy mark 2 version with shipping to Australia?


 
My guess is that most shops that sells version I now, will change to version II when the stock runs out.


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## chewy78 (Feb 8, 2012)

nice review


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## tobrien (Mar 11, 2012)

i've been using this a while now, since i suppose around november, and it's been a great charger!


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## hank (Mar 11, 2012)

I'd urge you to lay out a test plan that the rest of us can follow, even a few simple tests -- so we can compare results.

Nothing against this particular charger, it's got a good reputation.

But -- as a general thing -- I hope those who get review copies will think about things to measure and publish so the rest of us who do buy them can check that ours are built to the same specification.

Here's why:

I've never trusted "review copies" of any electrical appliance -- the "go buy them off the shelf and test" is too expensive for us amateurs, Consumer Reports does it for a reason though.

I recall decades ago gossip that for some computer plastic cases and power strips, the UL fire safety tests were being done on specially crafted materials prepared by the manufacturers to pass the tests -- and then they shipped cheaper stuff that burned easier. 

Took a long time to identify the problem as most house fires started by home electronics were so complete that there was no evidence left of how it started. Here's a recent blog about the issue:

http://oscarchristensen.articlealley.com/home-fire-danger-from-consumer-electronics-2280587.html

And this finds the State Fire Marshals reports:
https://duckduckgo.com/?q=consumer+electronics+home+"state+fire+marshals"

Photo: Consumer Warning: Potential Fire Hazard With Chinese ...
WASHINGTON, Oct. 29 /PRNewswire-USNewswire/ -- The National Association of State Fire Marshals, retailers and certain electronics ... game devices, "boomboxes," computer keyboards, speakers, ink-jet printers and all other consumer electronic and computer equipment sold for use in the home.
National Association of State Fire Marshals 
http://consumerelectronicsnet.com/articles/viewarticle.jsp?id=1504418 

[PDF] FIRE PERFORMANCE OF FLAME RETARDED POLYMERS USED IN CONSUMER ...
FIRE PERFORMANCE OF FLAME RETARDED POLYMERS USED IN CONSUMER ELECTRONICS Matthew Bundy* & Thomas ... of these issues are important due to an increasing number of both candles and electronics in the home. ... National Testing and Research Institute (SP) and the National Association of State Fire Marshals ...
http://fire.nist.gov/bfrlpubs/fire05/PDF/f05013.pdf 

As Mr. Reagan said: "Trust, but verify."


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## madecov (Mar 11, 2012)

Since I have recently gotten numerous new 18650 cells and several other sizes, I decided to get one of these chargers. I will mostly use it with AW 16340 cells with spacers. 
I also have the 4 sevens single bat charger and the PILA IBC.

My Maelstrom S-18 can be fed often easily.


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## iron potato (Mar 17, 2012)

Got my WP6 II today in the mail, quickly unboxed, powered up & slapped in 4 pcs of Hi-Max 2600mAh 18650, with another 2 slots taken up by UltraFire 18350, after charge completed, I measured 4.20v each fresh from charger...pretty impressive :thumbsup:


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## madecov (Mar 17, 2012)

I got mine this week. I ordered it due to this positive review.
I want to be able to keep an S-18 fed well so charging 6 16340 cells is very convenient.


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## chewy78 (Mar 17, 2012)

can hkj or someone explain to me again in simple  terms how it charges in 2 or more slots? what if i want to charge 3 cells? lets say in the left half of the charger. i got kinda confused with the channels and pairs and stuff lol. thanks . so if i charge 1 cell, does it charge at 600ma? or 1200 ma at 50%duty cycle? or does it charge at 1200ma with a 50% duty cycle when doing 2 cells? what will happen if i only charge 3 18650 cells at a time?


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## HKJ (Mar 17, 2012)

chewy78 said:


> can hkj or someone explain to me again in simple  terms how it charges in 2 or more slots? what if i want to charge 3 cells? lets say in the left half of the charger. i got kinda confused with the channels and pairs and stuff lol. thanks . so if i charge 1 cell, does it charge at 600ma? or 1200 ma at 50%duty cycle? or does it charge at 1200ma with a 50% duty cycle when doing 2 cells? what will happen if i only charge 3 18650 cells at a time?



If you want to charge 3 or less batteries, use slot #1, #3 and #5.

If you are using slot #1 and #2 at the same it it will double the current (i.e. 1200mA), but only charge 50% of the time in each slot, on average this is the same as full current (600mA) 100% of the time, but due to the way batteries works, it takes longer time to charge.

Looked at it another way: the average charge current is always the same in each slot (600mA), but the charge time will be longer when two adjacent slots are used.


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## chewy78 (Mar 17, 2012)

ok now it makes more sense  I would mostly be using it to charge 18650s and an occasion, a pair 17500s.


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## Husker (Feb 13, 2013)

Sorry,I know it's been a year since the last post!

I'm in need of a charger for 'Protected 3400mAh 18650 Li-ion Batteries' (still trying to figure where & what brand to buy) I ordered a 'OSTS TN31MB' now need to get 6 batteries + charger, is this still a good charger for what I'm after or is there a new & better one available?


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## HKJ (Feb 13, 2013)

Husker said:


> I'm in need of a charger for 'Protected 3400mAh 18650 Li-ion Batteries' (still trying to figure where & what brand to buy) I ordered a 'OSTS TN31MB' now need to get 6 batteries + charger, is this still a good charger for what I'm after or is there a new & better one available?



The charger does still do a decent job, but Xtar has made much better chargers, but only two channels (SP2 and VP1).


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## psychbeat (Feb 26, 2013)

I've been using mine a bunch the last 6mos and am happy with it. 
Apart from the slow charge time. 

Do you guys think it would be a bad idea to bridge the channels when I need to charge a single 18650 up quicker?

I know it charges differently with two bays next to each other occupied.


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## HKJ (Feb 26, 2013)

psychbeat said:


> Do you guys think it would be a bad idea to bridge the channels when I need to charge a single 18650 up quicker?



Yes.


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## psychbeat (Feb 26, 2013)

Ahh - so this is bad 

I used a nickel to bridge the pos. 
I'd never leave it unattended.


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## ven (Jan 9, 2014)

Thanks for review it helped me decide on an alternative 4+ bay.I ordered one a few week back mainly as a back up and to take work load off my i4 which is used daily.
Got it for £18.99 UK too which is reasonable imo,bonus with 6 bays too.I recently charged my 4 tm15 cells (xtar 2600) and noticed a noise from the charger(presume the norm) and it gives off a little heat too........well compared to my i4 which stays cool.I am presuming here that it gives a little more ma as the batteries got "warm" again compared to cool in the i4(same cells compared)
At home next to my vapex




I also noticed the 18650s in 2600 xtar flavour were quite a tight/secure fit......again more so over the i4(only other 18650 charger i have to compare)


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## CSSA (Jan 10, 2014)

I purchased an XTAR WP6 II to recharge 6 AW 16340 protected Li-ion batteries at a time to keep a recently purchased MMU-HD happy and fed. Since reading this review I'm wondering if this s not a good idea. If the AW 16340 actually has a capacity of about 500 mAh, and this charger charges each battery at 1200 mAh per hour pulsed half of the time, isn't this likely to be hard on the batteries? Even if you only charge 3 batteries at a time and it is charging at 600 mAh, isn't this still pushing the limit of what is good for the battery?


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## psychbeat (Jan 10, 2014)

CSSA said:


> I purchased an XTAR WP6 II to recharge 6 AW 16340 protected Li-ion batteries at a time to keep a recently purchased MMU-HD happy and fed. Since reading this review I'm wondering if this s not a good idea. If the AW 16340 actually has a capacity of about 500 mAh, and this charger charges each battery at 1200 mAh per hour pulsed half of the time, isn't this likely to be hard on the batteries? Even if you only charge 3 batteries at a time and it is charging at 600 mAh, isn't this still pushing the limit of what is good for the battery?



It's fine 
I've used mine on my 16340s weekly with no problems for a year at least. 

Have u seen the amperages the RC guys use on their lipos?!


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