ISDT C4 NiMH/Li-Ion Charger Review


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
Parting Shot
Up Next


I had seen this charger randomly around the internet and it looks so fancy.  I like fancy stuff.  It also looks like a very capable charger.  Here’s my review of it.  I’ll say up front (and this might be the best place, too) that this charger is is advanced enough that my typical charger-tester setup didn’t work well.  What I mean by that is the resistance in my usual setup got sensed by the charger and prevented higher current charging.

Official Specs


The going price on these seems to be around $60.  I got this review unit from GearBest.

Short Review

This charger has somewhat limited usefulness because it really only works with three types of cells I use.  That’s NiMH AA and AAA sized cells, and flat top unprotected 18650 cells.  In truth I use those types of cells a lot so this is a great charger for me.  And the actual capabilities of this charger make it fantastic!

Long Review

Key Features

  • Fast charging: support 3A per channel and max 8A output, quick charging
  • Max charging 6 batteries simultaneously: specially designed, the slots can charge different kinds of batteries at the same time, max 6 batteries
  • Smart charging: automatic battery type identification and auto-setting for accurate battery charging voltage and modes
  • 6 charging and discharging modes: 6 modes supports a wide range of battery charging options: charge, discharge, storage, cycle, activation, analysis
  • 2.4 inch IPS LCD screen: 178-degree wide visible angle, 3 backlights adjustable and visible under sunshine makes you easily know the charging conditions
  • USB output function: you can charge your phone with this charger
  • Wide input voltage: support 12 – 24V input to provide more choices for power sources
  • 3 protections: reverse polarity protection, over temperature protection, overcapacity protection to protect your charger and batteries

Manual and Packaging

The C4 ships in a very nice glossy coated and highly printed slip fit box  GearBest has their inventory sticker on the box, but fortunately it really blocks nothing imperative.

ISDT conveniently includes the manual in pdf format on their site.  It seems long at first, but really each language is only around 5 pages.

What’s Included

  • ISDT C4 charger
  • Wall plug (in my case it’s the European version)
  • ISDT Stickers
  • Manual


Build Quality and Durability

I was skeptical, just glancing at photos online, that this could be the ‘cheap’ type screen, or the ‘good kind’ of screen and surface.  It’s the good kind.  The buttons are capacitive type buttons.  That’s not my favorite thing, but they work fine.  The screen is very glossy, and ISDT includes a screen protector by default.


As far as hand feel and general use of the C4, it’s extremely well built.  And with the limited (or I should say “very specific”) size and type of cells this unit charges, the moving parts (of which there are zero) mean that the charger has fewer things to break, or wear.

There’s a fan on the back of the unit, which operates a surprising amount.  Even in situations when you might not think it’s going to operate.

Look at all the bays!  There are four AA bays, two AAA bays, and two 18650 bays. And technically one of those 18650 slots is a 26650 slot, too!  It’s an unusual design, and most conducive to charing one type or the other (by which I mean, it can be frustrating if you go to charge an 18650, but you already have a NiMH going).



Officially 122×85×38mm.

It’s a pretty square device, with a top (front) that slopes down from the screen to the bays.

Here are a few types of cells in the charger.  Eneloop Aa and unprotected 18650.  I did manage to get a button top Efest cell in there (and working) but generally only flat tops are going to work.


The C4 needs a minimum 12V (up to 24V) DC from a barrel plug, to the back of the device.  ISDT provides a wall plug for the C4, but in the case of the package I got, it was a European plug.  I have to assume that US plugs are available, but I only see a color variation available on GearBest (plug doesn’t seem specified).

In any case I was fortunate to still have the 12V wall plug from my SkyRC MC3000.  It fit and worked flawlessly for this application.

In case you don’t have a good source of 12V, but do have a desktop PC?  You could probably (I’m just saying probably, maybe… you know… don’t like burn your house down) craft a plug off the 12V rail that would power this charger very nicely.  That could be a horrible idea.  You didn’t hear it from me.  (I might make one just to see how this would work.  Anyone have a desktop I can borrow?) To be sure, there are already ready made products you could buy to connect 12V systems this way.

Anyway, once you have that bit of the Power story sorted, you’ll want to know what kind of charge this device can put into your cells.  The max power no matter what you’re trying to do, is 30W.  The manual and features state that the max charging current across all bays at once is 8A.  Well, the charger will charge only 2 18650 cells, and at a max of 3A.  So your max there will be just 6A (if we’re discussing the purely academic “specs” feature set).  And you’d never charge NiMH cells at 2A, so that’s not the way to get 8A.  I suppose the way to get 8A out of this system at once is to have four flat top 14500 cells in the “AA” Bays, and charge them at (max) 2A.  (Even that puts the wattage slightly over the max for the charger).  Unfortunately I don’t have four flat top 14500’s (I have only one), so I can’t say if this is fact.  I’m not sure where they get “8A specifically”.  (I’m sure there’s an obvious one I’m just not thinking of; forgive me.)

Moooostly that’s academic, sure.  But it’s still good to know what manufacturers are being honest with us.

There’s a USB plug on the top of the device, near the fan.  This is pass-through power only.  Any cells installed in the C4 do not power the USB.  It’s claimed to be a 2.1A output, and I found that to be true.  The C4 is able to provide 2.1A output down to about 4.9V, where the output shuts off.

USB Out.png

As I said above, the interface for the C4 is touch buttons on the right side of the display.


User Interface and Operation

There are many settings on this charger.  They can be adjusted by clicking the center button (kind of looks like a gear symbol).  Once clicked, many settings about the charger can be manipulated, including whether it runs in full auto, or whether you have much more granular control over the settings.  I run the charger in auto, and I’ve been very satisfied with the operation.  Even in auto, you can still manipulate the charge voltage and other settings.  The charger is good to detect chemistry, and smart about how it does so (something I’m not sure I can say about the MC3000, love it as I do).

Here are some screenshots of the settings available.  (This may not be entirely comprehensive, but it’s fairly close.)



That’s basically the splash screen.  Notice in the top right corner, the input voltage, listed at 15.3V.  To the right, you can see the “gear” icon, which is where settings may be accessed.

To access the main system settings (etc), hold the gear icon when no cells are in the charger.  A bunch of stuff can be changed.  Note the “Factory Setting” selection.  Clicking affirmative on that (which means moving the green bar down to it and then clicking the center button) automatically and without further warning resets the system to factory settings.  That seems… a little abrupt to me (it was when I did it accidentally, for sure).


Clicking “System Information” shows what firmware is installed.  The system is firmware-updateable.  Here’s where you can download the zip of the current fimware.  My device is on, and the current version is  There are a couple of fixes I’m interested in, like “NiMH charge optimization.”  Flashing new firmware is easy.  Just connect the device to a Windows machine, run the .exe from the downloaded zip, and the firmware will update.  It’s very quick, too (<1m).  Don’t have cells in the charger, and you will need 12V power (C4 can’t be powered via the micro-USB.)


Just for giggles, here’s with backlight on “Low.”


As far as charging cells, like I’ve said – I basically use the charger on Auto.  Here are some screenshots of that.


On Auto, you don’t even have to push start.  You may push start, but it’s not required:  Charging will start automatically if an appropriate cell is inserted properly.


Battery types supported:

(NiMH, NiCd, NiZn, Eneloop, Li-Ion, LiFePO4, LiHv).

There are also a bunch of possible tasks.


(Charge, Discharge, Storage, Cycle, Analysis, Activation.)

An important note on what all of those modes do is most easily presented by just pasting the image from their manual:

Screen Shot 2018-05-27 at 6.02.36 PM.png

I do not believe it’s possible to modify the terminal voltages on any of these settings.  It is possible to modify the default current settings.

Also note at the top of the screen there, it tells what cell type is in the charger.

Charging a cell gives a fancy little graph.  It’s not possible to export these graphs, as far as I can tell.  When the cell is actively charging, the top right section says “Charging” and also the graph is red.  When it’s finished, the graph turns green, and the charger says “Charge Done.”  This graph is a picture of the capacity being input to the cell.  Seems like more info would be nice, and should certainly be available, but this is the option.

Charging NiMH cells is just about the same.  Note the “79” and “81” on these images, at the bottom.  Those numbers are oriented along with the cells (see above, with an 18650, that these numbers are on the left side).  These numbers are essentially “percent full” and when the cell is full, this number switches to a green checkmark.

Another note about the 2 photos on the right above.  The charger automatically cycles displaying info between the cells installed every few seconds.  This can be turned off in settings.

Storage of a cell takes an 18650 down to 3.7V, great for storage and shipment, etc.  Also note that this “Task” has it’s own color, both on the graph and icon at left.  Purple.

Analysis performs a C>D>C on the cell.  Charge (from whatever state the cell is), then discharge to (unstated but I believe it’s around) 3.4V, and then charge fully again.  Interestingly when complete, “Analysis” doesn’t switch to “Analysis Done.”  But we can see that the capacity of the cell I was testing is 2651mAh from this test.

During my whole time using this charger, I didn’t notice that there were dedicated slots for AA NiMH cells.  This frustrated me and to be be honest I judged the charger harshly for it.  When I started writing the review I saw AAA support in the manual and I thought, “um nope.”  Welp I was wrong, and sure enough, there are two AAA slots.  I’m super pleased by that.  Here’s what it looks like when there is one AAA (left) and two AA (right) in the charger at once.


NiMH default is 1.0A, and termination voltage is 1.65V (Seems high!?, but maybe that’s ok? Let me know in the comments.)



This is a highly refined charger, and I happen to really love it.  My perfect charger would probably be the UI (or at the very least, the screen) from this device, with the software of the MC3000, and the bigger bays, too.  Even this very charger, with PC connectivity and software support, and maybe bigger bays (though, I do like this as is), is nearly perfect.

An incredible, unreasonable addition to this would be a bump out bay, for charging longer 18650 cells, bigger cells, or multiple cells in parallel….  Which is to say (just like my commentary on the MC3000), a balance plug on the side of this tiny charger would be ridiculously awesome.

What I like

  • UI is fantastic
  • Charges at claimed rates
  • Smart enough that Auto rocks
  • Very hard to put wrong cells in, and cells in wrong.

What I don’t like

  • Limited cell size support even among what it does support
  • Doesn’t have a balance charger (though as a 30W charger, this is reasonable)

Up Next

After tomorrow, I think I’m about to break into my personal stash of lights for reviews…. anything you want to see, please let me know!  Sinner, Solarforce, McGizmo Haiku, BLF GT… those are just a few choices.


  • This item was provided by GearBest for review.  I was not paid to write this review.
  • This content originally appeared at 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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