Xtar Over 4 Slim review by Mjag....The fastest charger ever?

Impatient much? Want the fastest charging out there cause you just can’t wait? Well Xtar may have the solution for you, the Over 4 Slim. Over 4 because it can charge at a max of 4.1A and slim because…it is skinny whinny? The name doesn’t exactly roll off the tongue, I just kept calling it the 4 amp charger cause I kept forgetting the name. After more than 6 weeks of use as my main charger I will go over the pros and cons and let you decide.

What you get

From Xtar’s website

Matches what I got


Fit and finish

The white and blue finish sure stands out compared to all the other black chargers I have. Here it is next to the Xtar SV2 Rocket which is the most compact charger I have.

Here is where all that extra power comes from, the SV2 Rocket wall adapter on the right next to the power brick of the Over 4 Slim on the left.

They include a pair of 5V/2.4A charging ports as well, nice touch and both of them worked fine for charging my internal battery mods.

The display screen is nice, bright and easy to read and shows the voltage, temperature, charging rate, % of battery and will show if one of the USB charging ports is also in use. In this pic I have one of my internal battery mods plugged in to USB 2 while I begin charging a pair of batteries at the same time.

Appears to be made of plastic but Xtar mentions it is a fire retardant material. Not that I have seen any metal chargers, none that I own, they are all made of plastic as well. The Over 4 Slim does have a nice satin like finish to it, overall a nice looking charger.

Is it really that fast?

Now let’s first get into if it is safe to charge at 4.1A, from what I have gathered from reading up on the subject it is as long as the temp of the batteries is monitored which the Over 4 Slim does via temp sensors.

It will also test the internal resistance of the battery and decide the proper current. I did try some of my old AWT 18500 batteries with it from my Provari days and after reading the internal resistance it set the charge rate at 2.1A. With the current batteries I use daily, mainly Sony VTC5A 18650, iJoy 20700 and various 26650’s it selected 4.1A but the user can change that if they wish to 2A or 1A . It fits all the sizes I mentioned, even a 21700 I just received during my review evaluation.

Now let me just say I am no Battery Mooch, for those of you who do not know Mooch is the battery guru for the vaping industry and a hugely valuable resource. I have read his recommendations and charging advice. It is known that Li-ion batteries we use don’t last forever, they have a discharge cycle which I have seen estimates of between 300 to 500 and from there the capacity begins to fall. To extend life it is recommended to charge at a slower rate, preferably 0.5A so keep in mind that 4.1A charging will decrease the capacity faster, how much faster I really don’t know but there is a drawback to the speed.

Now in my use I can say this thing is wicked fast, it was the only charger I used for more than 6 weeks and the speed is addicting. Just as I started writing this review I popped in a pair of 20700’s which were at about 3.65V each and they are already done…wow. I used it with almost all my batteries, the only exceptions were my 3 and 4 battery married sets, this is a con for those with triple or quad battery mods…only 2 slots.
I did not time all my battery charges, usually by the time I got back to the charger they were already done and this thing doesn’t have a timer. I did measure the time for a pair of LG HG2 3000 mah batteries though, both discharged to 3.36V and it took 46 minutes to fully charge. A single Samsung 25R 2500mah battery discharged to 3.3V only took 30min for full charge.

I was curious to find out if it would do the full 4.1A and if it was indeed twice as fast as one of my other chargers at 2A. I took a pair of Basen 4500mah 26650 batteries down to as close as I could get them, 1 was 3.29V and the other 3.33V, close enough. Using my Hohmbase charger (I also have 2 other Xtar chargers but decided to use a different brand) I popped in the 3.33V in there and set it to 2A charge. I then placed the 3.29V Basen into the Xtar and it set it to 4.1V after running it’s diagnostics first. Now I would like to tell you exactly the times, I had written it down on a post it note since I was in a hurry and my normal notes were in another room. My mistake for leaving it out as it got thrown away…thank you honey ;-p. I can tell you though based on my remarkable memory…ok, stop snickering, it is good enough…the Xtar Over 4 Slim at 4.1A was exactly twice as fast as the Hohmbase at 2A, it was on the nose twice as fast, very impressive.

Now I have to point out that the batteries will get pretty warm charging at 4.1A, the warmest it got was 48C which equates to 118F but mostly batteries were 44C which is 111F. The Over 4 Slim does measure temp and if the battery gets too hot it will automatically lower the charge current to keep it in check. I never got to the point of having protection kick and lower the rate but I was not in front of the charger the entire time. Of course this warmth is one of the reasons why you will lower the amount of charge cycles of your batteries, can’t charge at such a high rate without it getting warm. The cost of speed will be that your batteries will degrade at a faster rate, by how much depends on a lot of factors but 4.1A charging is one of them.

Now I have to admit, prior to getting the Xtar Over 4 Slim I would have sometimes 3 or 4 chargers going at the same time, I have 6 chargers, Over 4 Slim included. My time with the Over 4 Slim the charges were so fast I only used my other chargers when I need to charge a married set of 3 or 4 batteries. Never thought 1 charger would ever be enough but for the vast majority of the time the Over 4 Slim was all I needed.


  • To my knowledge the fastest charger on the market
  • Lives up to it’s rated 4.1A charging, twice as fast as my other chargers at 2A
  • Fits every vaping battery I have including the new 21700 batteries with no problem
  • User adjustable from 1A, 2A and 4.1A charging
  • Monitors battery temps and compensates if they get too hot
  • Measures internal resistance and chooses appropriate charging speed
  • Flawless operation in the 6+ weeks I have used it
  • Includes a pair of 5V/2.4A USB ports
  • Smooth battery sled springs


  • Only 2 charging ports, only a con if you need to charge more than 2 married batteries
  • Higher rate charging will diminish the life of your batteries, by how much is dependent on a lot of factors
  • Batteries can get pretty warm, up to 48C or 118F in my testing at 4.1A

Final thoughts

I have to say that charging at 4.1A is pretty addictive, more so if you are like me and never charge batteries unattended. Not like I am standing in front of the charger the whole time, just won’t charge when I am out and about or when we are sleeping. To go from having 3 to 4 chargers going at once to just one fast as hell charger was a real experience and one I will continue with the Xtar Over 4 Slim, it is a crazy cool charger to have around.

Now you have to weigh the Pros and Cons on this one, are you ok sacrificing some of the life of your batteries for the convenience of speed? If the average of a Li-ion batteries available stored energy begins to fall at 300 to 500 charge cycles at a slow 0.5A charge rate would 270 to 450 or possibly 240 to 400 cycles for a MUCH faster 4.1A charging rate be worth it for you? Please keep in mind the batteries will continue to work, it is just that the available stored energy begins to go down, sort of like your cell phone, you get less talk time as the battery begins to age.

Personally I am OK with sacrificing some life at the end of my batteries usefulness as I mainly use multi battery mods where the effect is not as noticeable. For single 18650 mods I will continue to charge at a lower rate, this is where it will get noticeable. My high mah 26650’s will be exclusive to the Xtar Over 4 Slim though, takes forever to charge a 4500mah 26650 in my other chargers.

You can find out more info at Xtar’s site on the Over 4 Slim: http://www.xtar.cc/products_detail/productId=185.html

I will normally post where to buy products I review but the only place I could find so far was on ebay at what looked like a nah nah nah, I got it so you gotta pay a higher price so I won’t post that. I would expect it to be available soon at most places and if I find a great deal I will update here.

Thanks to Xtar for sending me the Over 4 Slim for review, it will get a lot of use by me for sure!

Check out how this stacks up to other tasty gear and meet the Steampugs team of reviewers. Your bound to have a good time and read up on some great products, not so great ones too http://www.steampugs.co.uk/


Thanks for the review! Actually cell longevity is the main reason I don’t consider super-quick chargers, I’m glad you made a point to mention it.


Great review. Something to think about for sure. Does it measure mah stored? That is and index I would like to have on tap.


Thanks @TW12, yeah, I could not do the review without mentioning that, would be irresponsible and I always want to put as much facts as I can so people can make an informed decision.

Thank you @SmilingOgre. No indication of mah, it is a pretty simple charger, not many changes can be made aside from the charging speed and dimming the screen.


The review title caught my eye and I thought "Cool, fast battery charging. Gonna get me one!"
But as I read through your review and saw there were some caveats I realized that you may have saved me from an impulse purchase. I may still pull the trigger on one but the depth of information gave me something to definitely think about.
Thank you!


I saw the title and thought differently @TorturedZen. I know that quicker charging results in lower life so i thought " How many amps are the pumping those poor batteries with now?" :rofl:
I charge at 750ma since i’d rather have the life span. Whats 1 extra hour when u have to wait anyway unless that it’s that poor fella w/ only 1 batt or set (in that case i am sure the community will gladly donate a few) . Another great review, always a pleasure to read!!


You know what brother…you’re bang on, I am so addicted to this thing, it sits next to my bed on a shelf with 2 other 4 slot chargers and I haven’t used them since I got this, and yes…I have been charging at 4.1a pretty much the whole time, naughty I know…if I am getting ready for work I can slap them in and they are done before I leave…unreal thing…need a 4 slot now :smiling_imp:
awesome write up man…as ever :wink::facepunch:


I know enough about batteries to not to blow my face off. Also know that it’s better to charge them in a dedicated charger, rather than in the mod w/USB. But I wasn’t aware that quick charging would shorten their efficiency.


They addressed the safety issue w/ the fast charge times w/ the temp sensors. I would be interested to see info on exactly how much it affects the life span and what would be the fasted/highest amp to charge at before it does. The study could be out there, i just havent looked


Thanks for the review. I have been looking to add another charger. I am currently using a 4 slot and a 2 slot and seem to have enough batteries in my rotation that I always have plenty of spares, but have limited myself to 4 mods in use at any one time and box the rest. Thats a hard thing to do lol

How are the Xtar chargers overall? How do they compare to other brands? They seem reasonably priced and I have been considering picking up one of their 4 slot chargers. Thanks again for another great review.


@TorturedZen yeah, there is a drawback but that is usually the case when you try to speed up the process. You can possibly charge your batteries at 4.1A everyday for a year before they begin to lose capacity, a lot of that has to do with the quality of the battery itself. If I only had a couple of pairs of batteries than this would be the charger I would get, the time saving alone is worth having to replace batteries sooner but everyone has to make that decision for themselves. Thanks for the kind words, really appreciate it.

Thanks @worm1. I do hope it stops here at 4.1A and we don’t see another company come out with a 5A, we already suffered the wattage wars with mods, don’t need that with chargers. I have seen Mooch hem and haw on the faster charging rates, no doubt it will age the battery faster but in reality how many people will notice, that is the real question.

LOL @Steampugs, I am glad it is this we are addicted to and not crack. I did have to point out the detrimental effects but what might be getting lost on how awesome this charger is, when I go back to my slower chargers I can get a little impatient now that I know what real speed is like. Your right, I would so take a 4 slut…errr, I mean slot version of this, degradation be damned…lol. Thanks brother

Hey @Jim22. My first high end charger was an Xtar and it still works like new, I have no complaints. I also have a Xtar SV2 I reviewed a while back, another solid performer. The only other 2 brands I have is an Efest Blu6 which has been great and a Hohmbase which is my favorite of the bunch as it has a Battery Doctor feature which I use every 6 months to keep my batteries in tip top shape. None of them snap my head back like the Over 4 Slim though as far as speed, I am constantly shocked at how fast my batteries are done it is hard to go back to the others.


Thanks for the detailed review, I like the idea of fast charging, mine seem to take forever


Kick ass review Mjag! I really need to get another charger and this one sounds awesome with the speedy charging! I’m right there with you, for the convenience of a super fast charge I’m totally willing to sacrifice a little bit of battery life in the end.


Thanks @Grubby and @VapeyMama

It really is an experience to charge this quick, If you do get one let me know what you think VM :+1:


Nice review once again bro and this time on something way different from the normal mods and attys.
I liked it and if i ever need a quick charger i now know what to get.


Thank you @mjag. Excellent review.
I have the same device.
The only thing that is slightly annoying is that when I install the battery, the device sets the maximum charging current. And I will reduce it manually.


Thanks @Norseman and @Nextron

It’s cool sometimes to break away from the norm of vape reviews, we all need to charge batteries.


@mjag Thanks very much for the linkage here. I’m MORE than curious about this one. Thank you again.


No problem man and thank you as well.

I just slapped a pair of 21700’s in the O4S since the only other pair I have are being used. This 4 amp charging can be a life saver when your pressed for time.


I’m assuming if it weren’t for the temp sensors, charging @ 4A could reduce the battery life @mjag ??