Sorry I am totally wrong. I thought I read that somewhere. I will play with mine.
I am having the same problem. If i use the left charging bay the led flashes red/green and does not charge. I have just put the battery into the right hand charging bay and have a solid red led so it's charging.
Mine does the same thing 
. Also with a EagleTac 2400mAh...Weird
Me too.
Mine will fix itself after I switch the batteries around. Weird. I emailed Serena about this. No response and it's been over a month.
Now this is on the original first version Xtar WP2.
Similar problem as others have noted with left channel. Contacted Jason at SBFlashlight and he asked me to return it. He has forwarded my description of the problem along posts from here to Xtar. He has another batch coming in shortly and hopefully this issue will be corrected. Response time from initial email was less than 6 hours...pretty darn good based on my experience. Jason also indicated that there may be a group buy here in the near future for this charger. I really like this charger and hope to get a replacement in near future.
Sent a messege to Protactical on ebay. He told me send it back and he would send out a replacement. Very satisfied with his service.
same here but if you charge two batteries, does the left channel charge? Mine does.
I bought two from Serena. Both are perfect. Can you post where you bought them from?
Bought mine here: http://www.ebay.com/itm/XTAR-WP2-II-Charger-Newest-Model-18650-18700-Batt-/160643577424?pt=US_Flashlights&hash=item25671a7650
Been using the 1A charge setting now and left bay charges just fine. But now this thing seems to overcharge everytime to over 4,2V. Kinda forgot some unprotected panasonics in this thing and measured 4,27V. What do you think, is it still safe to use these cells?
After some testing I have the same problem as humppa. If I'm using the 1A setting the charger overcharges the batteries to 4.27V and 4.24V, but if I'm using the 500mA setting it terminates fine just below 4.20V.
I did a test run on it yesterday and to charge 2pcs 2600mAH XTAR took over 5.5 hours, by then I had to go to bed so I unplugged it. The batteries read 4.24V and 4.18V.
What do you guys think, acceptable or just plain broken?
Where did you get you wp2 ii? The one I bought from ebay charges at 4.17V consistently, for both 14500/500ma and 18650/1A setups, at both channels. I charge two at a time.
When I get the one I ordered from Serena I'll let you know how it goes.
I bought mine form Serena here on the forum.
Glad to here yours working as intended, I think I might send Serena an email
Just here to say:
Mine gives rather constantly 4,15-4,18V.
1A and 500mA.
It might have to do with the battery. I have some crappy ultrafire with high resistance and it charges to only 4.05V. Check also the batteries of your DMM.
I'm confused by the label, OUTPUT, above the USB slot. "Output" means "Plug in your external device here to charge it." But you all seem to be describing "USB input: "Plug the charger into your computer and use your computer to power the charger." Which is is?
It is to charge your telephone from hot batteries in the Xtar.
Thanks. What about the switch labeled 2-1-0. I've read conflicting accounts about 2 vs 1, and NOTHING about the 0.
Does the 2 mean "Use 2 slots?" "Charge at 1 amp total?" or "Charge at 1 amp per channel?"
If I'm charging 2 IMR 14500 cells, should I choose 2 (for 2 slots) or 1 (for the lower charging voltage?)
If I'm charging only 1 cell, may I use the right slot? Or must I use the left?
When would you select 0?
1 is charge cells at .5 amp
2 is charge cells at 1.0 amp
0 is charge cell phone from charged cells....even if charger is unplugged