Im taking a look at the Xtar WP2 Battery charger ..
14500 / 14650 / 17670 / 18500 / 18650 / 18700
Operating temp 0 - 40deg C
Input 12VDC 650mA
Rated Voltage 4.2v
Constant Charge current 600mA +-10%
Cut off voltage 4.2v +-1%
Cut off Current 60mA +-10%
Weight 70g
The charger comes with a very small power supply [ 12VDC ] , about the size of a mobile phone charger , and it barely seem to get warm charging a single cell at a time .
The charger does in deed charge at a constant current of 600mA , at least mine did , right up to 4v at which point the charge current began to drop .
@ 4.01v it was 580mA
@ 4.1v it was 280mA
@ 4.14 it was 180mA
With mine the termination current [ just before going green ] was 65mA .
Now this charger does not fully terminate , I did monitor a current of 0.04mA , and then it would jump to 0.11mA , then back to 0.04mA , and then up to say 0.23mA and back again to 0.04mA .
I can only suggest that this behavior is a form of monitoring the state of the battery , as it seems to mimic the way the battery is charged , which is similar to the WF-139 , a sort of pulse charging , whereby the charger stops to monitor the battery state then continues charging .
I cant say this is a bad thing as the current is so low , that it would take several hours just to feed the battery a single mA , so pulling the battery is no where near as critical , as with a charger , trickle charging at 40mA .
In fact this monitoring , I believe is a feature of this charger , for long term storage of the battery in the charger , so when the battery discharges to a certain level , the charger automatically tops it up again , and then continues monitoring the battery . [ As to whether you wish to use such a feature , I leave up to you ]
I put several batteries through this charger , and they terminated from 4.15v all the way to 4.19v . I dare say we have another charger that may be sensitive to the internal resistance of batteries as they near max charge . [ Maybe ] The charge voltage seems to about 0.09v above the battery voltage as its charging , until about the end when it seems to max out at 4.22v or so .
Overall , Im impressed with this charger , Its brand new , and this one was sourced from flea bay . The very low monitoring current at the end of the charge is so low as not to be an issue , and I would be personally in no real hurry to pull the batteries , I would rate this a very decent charger for the money , and one which should not have any issues with the length of 18650 batteries .
There you have it , another weapon to chose from to charge those 18650's
Does not seem to get much play on the other Forum ..
This charger should be given some consideration , considering its not too bad for the $$
How's this XTAR charger compared to, lets say, a double bay Trustfire? I have a Trustfire charger and another one bay, portable one. I recently got a Powerex charger for my NiMH's and I believe I could buy something better for my LiIons also. How well does an XTar fill the bill?
I bought this one for a friend and made a test charge on two pink protected UltraFire 18650 2600mAh.
Battery 1: New, about 4 cycles. Cutoff at 4.16V, 4.16V after a couple of hours resting.
Battery 2: Old, about 2 years, MANY cycles. Cutoff at 4.18V, 4.16 after a couple of hours resting.
I then used my Turnigy Accucel 6 to top them off.
Battery 1: 70 mAh
Battery 2: 73 mAh
Not a very scientific test, but still.
I like this charger. I doesn't overcharge and that to me is the most important part, feels safe. The cells are around 2400mAh so "loosing" about 70mAh I feel is OK as long as you can trust the charger not making a fire. From what I've read and with this test I certainly would like to recommend this one as a good cheap charger.
I ordered one off ebay last week. Got it for $13 with free shipping. The delivery estimate is almost 2 months, but it's already shipped. Can't imagine it taking more than a few weeks..
