XTAR Over 4 Slim 2-bay charger

Official Specs
Short Review
Long Review  
  Key Features
  Manual and Packaging
  What's Included
  Build Quality and Durability
  User Interface and Operation
  What I like
  What I don't like
Up Next


I’ve started talking to XTAR a good bit more lately, and after my last XTAR review (of the VC2 Plus Master), this just released XTAR charger showed up in the mail one day.  This is the XTAR Over 4 Slim.  “Over 4” is an indication of performance – this unit is rated for charing at FOUR POINT ONE amps!!  4.1A charging.

Official Specs

Fast and Safe.

· Max 2×4.1A, the fastest charger ever
· Impressive low temperature rise
· Battery internal resistance testing protection
· Battery temperature testing with overheat protection
· 1A/2A/4.1A optional current for each slot
· Dual 5V/2.4A USB ports
· Informative LCD screen display
· All-around protections


New enough that I’m not even seeing it for sale!  And XTAR doesn’t list a price on their site, either.

Short Review

Regardless of the 4.1A capability of this charger, I really like the build and material of it.  It’s certainly capable of high current, and the body is a very pleasant material.  Screen’s good…. it’s a nice charger!  Wish it was good for NiMH and also don’t care for the fact that it’s made for longer cells only.

Long Review

Manual and Packaging

XTAR is using a very fancy package here, with a very designed, printed sleeve, and a flip top box holding the goods.  The printing is descriptive enough, and shows the product well.

The manual is a gigantic piece of paper, with 8 languages printed on.  Each language occupies approximately 2″x 12″ of the paper.  The manual is fine.  It doesn’t show all that much more than the box, but has a good bit more verbiage.


What’s Included

  • XTAR Over 4 Slim
  • Wall wart with barrel plug
  • Manual


Build Quality and Durability

This charger is next-level with the body.  It’s plastic I can’t recall seeing on a charger before, and it’s extremely nice.  It’s grippy.  Granted grippy isn’t something one really needs in a charger body, but….


The screen is bright, and there are two green leds, too.

There’s also a black version, but all I’ve seen on the street for now is the white and blue.

Around the body of the charger, one can see two USB outputs, capable of 2.4A each, and on the back the barrel plug input.

On the back, see the rubber feet that will help keep the charger in place.  Included too is screen printed text of what cells are appropriate in this charger.



Officially this charger is 75x149x33mm.  It’s probably average size for a 2-bay charger capable of charging 2-up 26650 cells.

Note that the two bays are not suitable for short cells.  This is intended for longer cells, such at 18650.

Below you can see how long and wide the Over 4 Slim is, beside a Convoy S2+, and a much more obscure light on the right.


The Over 4 Slim receives power from an included wall wart, capable of 4A at 12V.  This is a nicely rated wall wart.  Of course it really must be, since this charger is intending to charge the appropriate cells at 4.1A!!

Aside from being able to charge cells quickly, the Over 4 Slim can also output loads of current.  There are two USB outs, which are each capable of 2.4A.  I was able to test these individually, but not concurrently.  I can confirm that they are both capable of 2.4A, and voltage only dips to around 4.7-4.8V.  Above 2.4A, the output drops out, and turns off.


User Interface and Operation

As mentioned above, this charger is meant for bigger cells.  That is, 18650 size or bigger.  It will not fit, for example, 14500 cells (or smaller).  Also one might not want to charge these smaller cells in this charger, since it’s slowest option is 1A (which might be too high current for smaller cells.)

Below you may see the unit in use.  Display lit, and unlit, and the little green LEDs just above the screen.  Note that the display flashes the internal resistance of the cell.  It does this very briefly and then it’s gone.  No combination of button presses could bring it back as far as I could tell.

I performed a few tests on this charger – one at each current rating.  I’m not sure they’re quite useful since I’m testing with an 18650.  The reason being, the charger at any of the current options gets the cell from the CC phase to the CV phase so quickly, it doesn’t stay at the promised high current for long anyway.  That’s expected, and fine.

We can note, however that, the high current rates are actually faster charging the cell to 4.2V.  I’ll add that my means of logging this charging is actually out of spec at 4.1A, so I can’t measure that fairly anyway.  But we can say it’s certainly faster!


The LEDs just above the display have a few uses, as follows:
Green: standby/fully charged/poor contact/polarity reverrsed
Red: charging/activacting
No Light: Power supply not connected.

So if the device is plugged in, these LEDs should be lit either red or green.

Another note about power:  The device will attempt to charge the cell at 4.1A.  If the cell doesn’t meet the requirements (due to internal resistance), current will be stepped down.  Temperature is also monitored (that’s what the little button looking thing in the bay is for), and if the cell gets too hot, current will be stepped down to manage temperature.

And finally, this device is not a powerbank.  If wall power is not supplied, the USB Ports are completely turned off.  Even with fully charged cells in both bays.


What I like

  • Fast charging
  • Build quality is great
  • Temperature sensor
  • Fast USB out

What I don’t like

  • Not for short cells
  • Not for NiMH
  • No powerbank functionality

Up Next

Working on the Nitecore HC33!!


  • This item was provided by XTAR for review.  I was not paid to write this review.
  • This content originally appeared at zeroair.wordpress.com. Have a look there for the best experience!
  • Whether or not I have a coupon for this charger, I do have a bunch of coupons!!  Have a look at my spreadsheet for those coupons.  Note I’ve upgraded that sheet so that now, you may subscribe and get notifications when the sheet is edited!!

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