For review I have the WP2 Mark2 charger from Xtar , and after two days of testing I just might have some good news for the folks out there looking for a 18650 battery charger . http://www.xtarlight.com/en/05-chanpin/p-001-1.asp?styleid=132
XTAR WP2 II 14500/ 14650/ 17670/ 18500/ 18650/ 18700/ 10440/16340 3.7V Li-ion battery charger
Charging qualifications and structures
Operation Temperature: 0~40℃
Input AC: 12V DC / 1000mA
500mA CC Current: 500m A±5%
1000 A CC Current: 1000m A±5%
Cut-Off Voltage: 4.2±0.05V
CV Cut-off Current: <100mA
Standby Current: <20.0m A
TC Current (Battery Volt 2.0~3.0V): 80±20m A
Auto Recharging Threshold Value Voltage: 3.9±0.15V
USB Discharging qualifications and structures
Operation Temperature: 0~40℃
USB Interface Output Floating Voltage: 5.0V
Output Floating Voltage Ripple: <120 mV
Reactive Current: <10m A
Maximum Output Current: 500mA
Battery Output Cut-off Voltage: 2.80±0.15V
The MK2 is very close in appearance to the first version but there are some minor changes , and the most obvious are the changes to the contact tabs , both positive and negative . They both look to have been beefed up and extended [ re-shaped ] to make better contact with the battery or simply to be stronger , Im not sure , maybe both , but I have to say I never found either an issue with the first one .
But what these minor changes do in the MK2 is is tighten up the fit of the 18700 batteries , from room to spare in the MK1 to a some what snug fit in the MK2 , now its not something to worry about , unless you own even longer batteries than the Xtar 18700 cells .
Now lets talk about the charger ..
On the front is a 3 position switch , if you dont want to use the USB feature [ 5volt power ] then you only need to concern yourself with position 1 and 2 [ position 0 is for the USB ] . Position 1 gives you 500mA charge rate , and position 2 gives you 1A charge rate . The first thing I tested for was if charging more than one cell affected charge current , and Im very glad to say that the case is No . Whether you charge one or two cells does not affect charge rate , nor does it seem to make the charger run any warmer , giving me the feeling it can handle 2 cells and 1A for each channel with little trouble .
Lets look at how the charger behaves : Lets start with the 1A setting
I was using two batteries Bat-1 @ 3.03v and Bat-2 @ 3.4v to start ... Both channels were doing 1A
I was monitoring the charge rate as the batteries charged , and at 3.84v the charge rate had dropped to 800mA
At 3.99v the charge rate was down to 500mA
At 4.07v it was down to 300mA
At 4.12v it was down to 140mA
And the charge terminated @ 4.14v [ tested battery voltage ]
Now lets see the 500mA results :
On the 500mA setting , the charge rate was 520mA , and it stayed there right up to 3.9v [ tested batt voltage ] and dropped to 400mA at 3.99v , 290mA at 4.07v and 160mA at 4.12v and the battery terminated at 4.14v ...
Battery termination :
I have charged over a dozen cells [ 18650 ] in two days and they all terminated at an average of 4.15v [ tested battery voltage ] .. Lowest was 4.14v and the highest was 4.16v .
Standby Current :
Now this charger does not fully turn of , but I did only measure some 0.11mA current when the charger completed the charge . Lets put that in perspective , that's 11% of one mA . So worrying about when you pull the battery should not be an issue ..
With termination voltage around 4.15v and a standby current of 0.11mA , it would take 10 hours to dump 1.1mA into the cell , and that leads one to call this a safe charger . [ based on this charger ]
Some pictures :
Conclusion :
My charger came with the 12v cigarette power adapter , a adapter plug for the power supply [ for Australian outlets ] and the charger , and the user manual . I have to say this is a solid performing charger , with two charge current options , it really does help speed up the charge cycle [ 1A ] , it holds higher current longer [ again shortening charge time ] . The overall build quality looks to be excellent , and improved upon over the Mark 1 , which is nice to see [ A company try to make a better mouse trap ] . The charger still uses the pulse style charging [ similar to WF-139 , WF-188 ] where it charges and then stops to check the battery and then continues .. [ Hence the term pulse charging ]
The open voltage was 5.1v on one channel and 5.4v on the other [ if this makes any difference ] ...
With some chargers advertising 1A charge rate , they can only sustain it with one battery and as soon as a second cell goes in the charge rate halves , well not with the WP2 MK2 , with two cells , it not only maintains the charge rate , but also there is no sag from the load of the 2nd cell , now that's nice .
Termination is between 4.14v and 4.16v , and some covet such chargers as it may extend the service life of batteries by not pushing the very max charge possible into them . And for some one that uses there batteries hard , say a security person who may do night shift and use a flashlight a lot , and recharges daily putting a lot of cycles on a battery , extending a batteries service life can make good sense , and for the average Joe looking for as safe as possible a charger ? , the Xtar WP2 Mark2 makes the grade with room to spare .
5v USB
Now I don't personally have much use for the 5v USB port , but then I thought , don't I have a USB AA charger ..
It took about an hour and fifteen minutes to charge a single AAA from 1.11v [ rested but fully depleted ] to 1.36v .. This could be a nice feature if you have a device you wish to keep powered [ VIA USB ] or in this case , charging a AAA battery ..
18650 was at 4.15v , AAA was 1.11v , on completion the AAA was 1.36v and the 18650 was 3.9v , this was a older Ultrafire 18650 with a capacity around 1500mAh
Only the left channel gives the USB port power , select 0 on the 3 position switch at the front of the charger and then plug in your device of choice , and the limiting factor here will be the battery capacity of the 18650 [ or battery chosen to power the USB port ] . This could be handy when out camping , especially as cell phones for example have become a very important life saving device , that no one should be without , when venturing out where help is hard to find . The USB function is handy , but lets not forget , this a a nice solid charger , and I ran it hard for 2 days , and I saw no reason not to recommend this charger , in fact , if this sample is the norm , then I would highly recommend it , especially to first time Li-ion users who may not own a Multimeter , or be aware of Li-ion procedures .
I will continue to use this charger as much as possible , ATM I have run out of batteries to charge , but if anything should change , I will do a update .
