Maha Energy MH-C204U Compact USB AA/AAA Charger Power Bank Review @
By: Michael Phrakaysone


We are addicted to batteries in today's portable world.  Our lives revolve around batteries in devices we use everyday such as notebooks, smartphones, GoPro action cameras, tablets, GPS, Bluetooth handsets, iPods, Nintendo 3DS, self balancing unicycles, and tons more items used day in and day out.  And we all know that batteries eventually become depleted.  I've noticed for many years now that battery technology has become stagnate.  Battery life has not improved much over the years as drastically as some other different technologies have excelled in growth.  We are stuck with what we currently have.   
And that is why we have rechargeable USB power banks saturated all over the market now, so that we can top up our devices that seemingly die so quickly on the go, on the road, when we don't have access to a power outlet, or in an emergency.   

The problem is finding a good rechargeable power bank that doesn't potentially kill you.  Have you seen my Stanley FatMax LEDLISL 10W Lithium-Ion LED rechargeable spotlight review?  The flashlight contains several warning stickers on the unit relating to the Lithium-Ion battery inside, and more warnings inside the user's manual.  This is because Lithium-Ion batteries are made with a type of chemistry that can be dangerous when they are used and recharged/discharged improperly.  This is the same type of battery chemistry used in notebooks and similarly with smartphones (Lithium-polymer), and you've all heard of stories of notebook and smartphone fires and explosions because they were stored in the wrong conditions, exposed to high levels of heat, used improperly, one of the protections failed, or they were using a very cheap quality Lithium-ion or polymer battery. 

Generally in these cases with big name manufactures the products are safe and go through numerous worldwide strict safety testing standards and procedures, but these things can happen out of the blue and not even Apple is immune to overheating and exploding batteries.  Its why every Lithium-Ion device has safety protections that include a smart safety circuit that checks voltage and temperature as to prevent disaster from happening.  But unfortunately not all safety protection circuits are created equal.
We've already looked at rechargeable Power Banks that were utilizing Lithium-Ion batteries, these variants are widely available because they offer more capacity and customers always love bigger, however, get the wrong one (from the cheap alleys of China) and the potential for disaster could strike.  Today I'll be reviewing another Power Bank that gives you the alternative of using a battery chemistry that is in magnitudes safer than Lithium-Ion/Polymer.   So you can top up your devices and feel more safer in the process. 

Maha Energy has created a compact USB Power Bank that utilizes four (4) rechargeable NiMH (Nickel Metal Hydride) batteries instead of typical Lithium ones you usually see in this application.  The great thing Maha Energy have done is to make it interchangeable, meaning you can use any AA or AAA size NiMH batteries on the market in this USB Power Bank!  That is really creative and open minded on their part, not having a closed system.  Lastly to make things even better, Maha includes four (4) of their most popular IMEDION Low Self Discharge (LSD) 2400mAh AA batteries in the package so you can get up and running in no time.  IMEDION line of batteries from Maha Energy are designed with the latest and greatest in NiMH technology in order to retain up to 85% of battery capacity in one year.  If you know what Eneloops are, IMEDIONS are Maha's answer to those from Sanyo.  Regular non-LSD batteries self-discharge and lose its capacity when not in use up to 1% each day. 

Without further ado, let's get onto the Maha Energy MH-C204U Compact USB AA/AAA Charger Power Bank Review.

About Maha Energy Corporation

“Founded in 1993, Maha Energy Corporation is a global leader specializing in the design, manufacturing, and distribution of battery and charging technology for various industrial and consumer sectors. With state-of-the-art research labs and production facilities in Asia, and sales & marketing offices in North America and Europe, Maha creates a global service network for both standard and custom-designed applications.

In addition to PowerEx brand products, a significant percentage of Maha Energy's revenue is generated from OEM & custom manufacturing businesses. Today, Maha manufactures millions of batteries and chargers sold under OEM and private brands for leading corporations in all industrial sectors. Maha's custom battery program also won key contracts from government and military agencies."

Maha Energy MH-C204U Product Overview

The Powerex MH-C204U USB Compact Travel Charger for AA /AAA NiMH Batteries charges up to 4 AA or AAA nickel-metal hydride (NiMH) rechargeable batteries. You can charge 2 or 4 batteries in about 4 hours.  This charger uses a micro-USB connector as power input using the supplied 5V/1A USB wall adapter.  The MH-C204U is equipped with a negative delta V microprocessor for precision charging to ensure batteries reach their full capacities without becoming overcharged.
The Powerex MH-C204U Compact Travel Charger can also provide a 5V/1A USB output using 4 charged AA or AAA batteries.  This way, you can have a power boost when your USB powered device such as your phone is low on battery. 
With the MH-C204U USB Compact Charger, you can:

  • CHARGE your batteries anywhere using a wall adapter, computer, solar panel, car charger, or Power Bank.
  • RECHARGE your USB devices anytime, such as your smart phone, digital camera, iPad, Apple Watch, and GoPro.

The charger is great for use in the home or office, as well as in the car (car adapter required, sold separately).

  • Charges 2 or 4 AA or AAA nickel-metal hydride or (NiMH) batteries
  • AA batteries take about 4 hr to charge, while AAA's take 2 hr (450mAh charge rate)
  • Charge your batteries anywhere around the world via the included 100-240VAC universal power adapter (may require optional plug converter)
  • Negative delta V microprocessor for precision charging to ensure batteries reach their full capacities without becoming overcharged
  • Includes a micro-USB cable and 5V/1A USB wall adapter
  • Includes 4 AA Imedion 2400mAh batteries and battery holder

First Impressions & Usage Observations

Maha Energy

The MH-C204U from Maha Energy comes packaged in a very basic corrugated box with a small slip-on design cover that covers part of the box.  It's not nearly as fancy a product as I've seen with the Maha Energy MH-C9000 Charger-Analyzer that I reviewed back in 2010 and the amount of focus into the product packaging shows.  Hopefully the same attention was put into the MH-C204U.

A picture of the product headlines the front cover and turning it over presents a brief overview of the back panel of the charger/USB power bank along with the main features of the charger that includes being able to charge 2 or 4 AA/AAA NiMH batteries at a rate of 450mAh, its abilities of being not only a battery charger but also an USB Power Bank outputting 5V/1A, the ability to recharge with the supplied micro USB cable and micro USB AC charge adapter, and the use of an intelligent microprocessor that controls the charge termination with "-deltaV" algorithm.  The product comes with a 1-year warranty.

Opening up the box shows the Maha MH-C204U charger power bank in all its glory.  Size wise it's a few inches in every direction larger than a credit card and is exactly the same size as my wallet.  I would have liked to see the product wrapped in protective plastic because it appeared quite dusty out of the box and had already some light scratches due to shifting and grinding against the cardboard box.  We can see the glossy exterior finish being friendly to dust and lint alike and for some of us that's an annoyance with glossy items.  In addition, fingerprints show up right away once being touched and held in the hand.  Maha would have done better if they had either gave a soft microfiber cloth inside the package or went with a matte finish from the start.

In the box are the following items:

Power Bank

  • Maha Energy MH-C204U Compact USB AA/AAA Charger Power Bank
  • Maha Energy Travel USB Charge Adapter (UL Listed Canada/US)
  • Flat Micro USB Charge Cable (105cm)
  • 4 AA IMEDION 2400mAh Low Self Discharge Batteries with carrying case

In my hands the Maha MH-C204U felt quite different to the feeling that the Maha MH-C9000 Charger-Analyzer gave me.  I have to say the plastic in this MH-C204U charger power bank fails to compare to the beefy and sturdy feeling displayed with the more expensive and matte finished MH-C9000 Charger-Analyzer.  This MH-C204U charger power bank feels kind of toy grade because the plastic MIL thickness is clearly thinner the MH-C9000 Charger-Analyzer.   By the way, that Maha MH-C9000 Charger-Analyzer I reviewed back in 2010 has been stellar and is still working to this day (without incident in late 2015) and still looks exactly the same with its matte finish and thicker plastic.  Quite impressive being that I've already used it regularly for close to five years.  I can tell immediately that a strict budget was used in making the Maha MH-C204U charger power bank.  But overall it's not as bad as I'm making it out to be, the fit and finish is still there and it doesn't flex like its flimsy. 

Overall the exterior feeling is quite decent considering the budget they obviously used.  I just wish Maha Energy went with a matte finish because after just a week of throwing it in my bad and travelling with it, it does looks trashed with swirls, scratches, and nicks.  I also felt that Maha Energy could have injected  some fun and personality as the design is very basic, with offering an assortment of colors, the only color it comes in is black.


Design wise the Maha MH-C204U charger power bank is as basic as can be, some may even say it's boring.  At least the edges are curved to give it some flair.  The front contains the Maha POWEREX logo, two LEDs just below and to the left of this logo, a plastic chrome strip which is where the battery compartment door opens and closes, and a thumb indentation that is supposed to help you open and close the compartment door with ease, but rather I found that it's so glossy and slippery that this thumb indentation should have been just below the chrome strip. 


Turning it to the bottom we find four rubber feet which does their job very well in preventing the Maha MH-C204U charger power bank from slipping and falling on surfaces.  We find a sticker that reveals that the charger power bank is made in Taiwan and that the charger input is 5V/1.2A and the charger output is USB 5V/1A.

Back Panel

Coming to the back panel we have from left to right a red power LED light, a single USB port for power bank capability, an ON/OFF switch, and micro USB port for recharging the batteries when they are depleted.  This might be me nitpicking, but I would have substituted the power ON/OFF switch for a pushbutton instead.  I wouldn't be surprised if this came down to prices of switches being cheaper than pushbuttons.  When you're using the power bank capabilities and the USB port is in use, sometimes the switch is hard to turn off.  For example, I'm using an USB LED flashlight on this MH-C204U and it's a little bit wider than the USB port itself, so it makes turning off the power switch more difficult as the switch is too close to the USB LED flashlight.  They could have spaced the power switch a little farther away from the USB port as there's lots of real estate to work with back there, so I have to get my finger nails in between to shut it off, or worse if I'm using a USB device that's larger then I have to use something like a pen to move the switch.  Sure I can just remove the USB LED flash or device right out of the USB port, but that's not the point.  A pushbutton would have been better in the long run.  But this issue doesn't always happen and will not happen when using a regular size connector.


Thankfully when you open the battery compartment door, the innards are of matte finish and everything is clearly labeled with symbols, signs, and text.  By default out of the box the setup is made to work with AA batteries, but very easily near the top of the positive poles there are tabs that you can use to pull down and convert the charging bay to accept smaller AAA battery types.  These tabs feel more rigid in use and give a audible click when pulled all the way down and locked into place.  Simply lift and lock back into place to revert back to AA charge bay setup.  Once finished just simply lift and close the battery compartment door.  This battery compartment door can be completely removed as they are on plastic rails that attach to the bottom of the charger power bank, but sometimes it can be slightly awkward putting it back on and wiggling it into place to shut.  But if you're constantly swapping and recharging batteries, it's better to take the battery compartment door completely off as it does tend to block and get in the way of the bottom of the unit.  Plus taking the door off will allow the batteries to passively cool down since they are side by side each other a little bit too closely for my liking.

The Maha MH-C204U charger power bank's battery bay is divided right down the middle because it is designed to recharge in either 2 or 4 battery configuration.  Two independent charging circuits, one on the left side, one on the right side.  It is not possible to charge only a single battery at a time.  The charger requires a minimum of 2 batteries to operate in either bay.  You can even mix and match and have a setup of 2 AA and 2 AAA charging at the same time, though there would be no sense in doing that since 4 AA IMEDION LSD batteries are included in the box, however, it is possible and good to know.  The user's manual advises against mixing and matching, but I've no issues doing so as they are done on separate bays.  If you did mix and match on the same bay then yes I would advise not to do that.  Mix and match on separate bays, left or right and not in the same side.

Once batteries in place and recharging, the front two LED's located just below and to the left of the POWEREX logo will turn on and cycle from red to green a three times while the charger analyzes the battery state and condition and will automatically start recharging with a solid red LED.  It charges at 450mA charge rate so it's not a quick charger in that sense, it will take some time (4-5 hours with included batteries from a discharged state).  The first and left LED is the indicator for the two batteries on the left side of the battery bay, while the second and right LED is obviously the charge indicator for the two batteries on the right side of the battery bay.  Once the batteries are fully recharged a solid green LED will show.  I would advise taking the batteries off as soon as you see those green lights because this charging circuit will continue to trickle charge your batteries at a small charge rate of 50mA, but I prefer charges that   If in the event the charger is turned on and is blinking constantly between red and green LED lights, that is to signify that the battery (or both) in that particular bay is defective (or has high impedance) and cannot be recharged any longer.

USB Charger Doctor

The small user's manual highly recommends that you charge and leave the batteries on the charger overnight to "fully activate the batteries".  I would not listen to this advice and would advise against leaving any batteries recharging overnight.  I come from the frame of thought that says do not leave your charger unattended and plus you'll feel more safer if something were to happen to the USB AC charge adapter overnight and you were not there to catch it.  I say once the charge is complete then there's no point to keep it on the charger.  I also do not trust trickle charges on NiMH batteries over extended periods of time especially as long as overnight, the battery can potentially become overcharged and damaged and or vent in the process.  I've had NiMH batteries on decent chargers that vented in the process of charging (though not in trickle stage, but there's always a chance), however, this is magnitudes safer than if that were to happen to a Lithium-ion or polymer battery igniting a fire and or explosion in worst case scenarios.  Can never be too safe.  Once batteries are done, remove or unplug them, and do not leave them and your charger unattended, that would be the best advice I would share.


Opening up the MH-C204U is simple as taking off the four rubber feet at the bottom of the device and unscrewing the Philip screws that hold everything together.  In my Maha Energy MH-C9000 Charger-Analyzer review back in 2010, I was happy to behold a professional soldering job that looked flawless and was clearly done by an automated machine and used a more complex PCB that had traces completed in between the PCB.  As I've already stated before, the MH-C9000 is more costlier and complex therefore more attention and care was given to it. 


The same cannot be said about the MH-C204U I'm reviewing today, a point I've already made in knowing this product is being made to a strict budget before even opening it.  Compare the PCB and soldering between the costlier MH-C9000 here and this MH-C204U here in HQ because they are night and day.  Yes at the end of the day it works, but the MH-C204U's soldering job does not inspire great confidence for many years of operation down the road if it can last, I expect multiple cracked/cold soldering joints down the road, but I could be wrong.  It's clearly hand soldered and even the traces are hand soldered, has multiple areas where flux and other bits and pieces of residue lay making it extremely dirty, some areas the soldering job looks clearly amateurish and other areas almost dare say poor, and there's areas where they were so close to overlapping and or interconnecting in places where they are not supposed to be touching.  It's just really inconsistent throughout and not of the Maha quality standard I'm used to seeing.  But it works...though I am not even remotely impressed with what I've seen.  Maha needed to spend just a little bit more money.   Click the picture below for a higher resolution image.


Before putting it back together and closing it up, I gave the PCB a wash with flux remover and scrub with a toothbrush to clean all the residue so it looks much cleaner than before, save for the soldering job I won't waste my time fixing.     

Where Can I Buy One? And for How Much?

The Maha Energy MH-C204U Compact USB AA/AAA Charger Power Bank can be purchased right now on sale through Amazon for $26.70 USD.  It's being shipped and sold directly from, and not a third party.

Why do I like Amazon?  They are fast, reliable, honest, and return policy is great.  I actually got money refunded back to my account after Amazon overcharged me on duty costs, talk about being an honest company, most others would keep the money and not say anything!

If you are thinking of purchasing the Maha Energy MH-C204U, or anything else for that matter, please use our Amazon link above, it will help us out greatly.  Thank you.


Some Amazon Deals That May Interest You!


I've used the Maha Energy MH-C204U compact USB AA/AAA charger power bank as much as I could for about five (5) months and happy to report that I've encountered no major issues relating to its recharging capabilities and power bank capabilities.  No it's not a perfect product as it does feel toy grade cheap in regards to its plastic exterior, it scratches and attracts fingerprints and dust like a magnet because its glossy, it doesn't charge particularly fast at only 450mA, and don't get me started on the amateur hour soldering job on the PCB, but at the end of the day it works.  But for me that's not enough. 

If that's good enough for you then by all means purchase it.  As for me, and for the $29.99USD Maha is asking for this, unfortunately I would have to say look elsewhere, and that makes me sad because I didn't expect Maha to cut this much corners.  What brings it down for me is the soldering job quality displayed in this product, it was the last thing I expected to see from Maha Energy and it's not something I feel comfortable in recommending being sloppy and all.  From what I've seen this should be sold at $9.99 and the only positive in this whole package are the IMEDION low self discharge batteries.