This is my post from July 2016:
I ended up going with the BT-C3100 v2.2, and have been completely impressed, and way beyond satisfied. Not just with the performance, but the longevity as well.
I feel like the current condition of the batteries I’ve charged on it speaks volumes!
Thank you for the linkage.
I got one last week in the mail… v2.2
I come from a usb-charger with only an indication of whether it’s charging or not, so I can’t be anything but impressed. Looks like it’s decent stuff but I can’t say much about how long it’ll keep doing its job, still brand new with only a dozen or so charges.
I like the fact that you can charge different types of batteries, different settings per charging slot, fast charging, slow charging, draining battery, battery test and what else. My batteries are charged at 4.19V when full, I can see how long they’re been charging, how much energy went in, … and it’s all cooled with a fan, has heat protection, …
More than I need really but I paid as much for this as a friend for a very basic 2-slot battery charger from nitecore in a local shop.
You might also mention that it’s been updated since this video to v2.2 (which IIRC had improvements to the fan, and another minor point or two), as well as a noticeable price drop!
If memory serves, I paid about $40 for mine two years ago. (A far cry below the $60 he mentions) 
I have one and I loves it 
@Sprkslfly hey bro, could you tell me what you think of this one? I love the features
Xtar Dragon VP4 Plus Li-ion/NiMH/11.1V 3S Charger and Battery Analyzer
SKU:Xtar Dragon VP4 PLUS
Availability: In Stock
$67.49 REGULAR PRICE $89.99
PRODUCT DETAILS
The Dragon VP4 Plus is Xtar’s top of the line battery charger and analyzer with a maximum charge rate of 2A on the outer two slots, and a system max of 1A for all 4 slots. The built in battery analyzer can discharge and recharge batteries displaying the capacity discharged and charged. The built in test leads will measure internal resistance in a battery as well as display the voltage. USB output and a 11.1V 3S dedicated charge port for lipo packs makes this one of the most feature rich chargers we carry.
Features
Test battery internal resistance and voltage
Test battery real capacity
Charge all popular Li-ion/Ni-MH batteries and 11.1V battery packs
Optional 0.5A/1.0A/2.0A charge currents
REFRESH Mode to eliminate memory effects
USB output function
Informative big LCD screen display
Record function
Specifications:
Input Power:DC 12V 3A
Cut-off voltage:
Li-ion 4.2V +/- 0.05V
Ni-MH/NiCD: 1.45V +/- 0.1V
USB Output Function: DC 5V 2.4A Max
11.1V/3S Battery Pack Charging Current: 1.0A
Charge current: 0.5A x 4, 1.0A x 4, 2.0A x 2
Dimensions: 158mm x 147mm x 40mm
Weight: 345g(without batteries and power cord)
Compatible with:
Li-ion: 10440/14500/14650/16340/17500/17670/18350/18490/18500/18650/18700/20700/21700/22650/25500/26650/32650
Ni-MH/Ni-CD: AAAA/AAA/AA/A/SC/C/D
Battery Pack: 11.1V/3S Battery Pack
What’s Included:
DRAGON VP4 Plus, Charger carrying pouch, probes, 12V/3A adapter, 3A Car adapter, Manual, Warranty Card
MANUFACTURED BY : Xtar
This is a plus for me, having 18650, 20700 and 3s lipos to charge. It is on my wish list.
I’ll ask you because I am striking out elsewhere, but does the Opus BT made for 21700 batteries?
@KC111 The Opus does 21700’s, 20700’s, 18650’s, and all the way down to AAA batteries !!!
BEST charger I have ever owned, and ALL I use now. Soo good, I picked up two backups.
The 3100 or 3400?
I have (3) 3100 v2.2’s. One has been under constant duty cycle since I got it, and 2 spares. I routinely charge 4 dead 21700’s with no issue.
How did you revive them??? 
Reading the reviews now, sounds like the cooling fan may potentially become a problem?
I have no idea, and I never replaced mine. Every once in a while you can hear them whir up/down, but then it’s quiet for the rest of the day. Fan works, never overheated, never replaced, never retired the unit.
https://lygte-info.dk/review/Review%20Charger%20Opus%20BT-C3100%20V2.1%20UK.html
slightly late on your question.
I also own this model (version 2.2) the result of the review is average level quality, the charging mode is not the best.
read the article is interesting, ciao
Wow, that’s a BIG one, I’ll have to check out this evening …
I had one problem battery that seems like it was a dud, despite it being brand new. I was hoping the Opus charger would fix it and it looks like it is fixed, it is showing as full, so I am thrilled about that.
