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


We are living in a battery-addicted world, where our daily lives revolve around the devices we use. From smartphones and tablets to action cameras and portable gaming consoles like the Nintendo 3DS, we rely on batteries to keep us connected and entertained. However, despite the advancements in various technologies, battery life seems to have hit a plateau. It's frustrating to see other technologies progressing while we're stuck with the same old battery limitations.

That's precisely why rechargeable USB power banks have flooded the market. They offer a convenient solution to top up our devices on the go, especially when we find ourselves without access to a power outlet or in emergency situations. But here's the catch: finding a reliable and safe rechargeable power bank can be a challenge. Trust me; I've come across some alarming cases, like the Stanley FatMax LEDLISL 10W Lithium-Ion LED rechargeable spotlight. This flashlight is plastered with warning stickers about its Lithium-Ion battery, and even the user manual emphasizes the potential dangers associated with it.

Lithium-Ion batteries, the same type used in notebooks and smartphones (Lithium-polymer), can be hazardous if mishandled during usage, recharging, or discharging. We've all heard stories of fires and explosions caused by improper storage, exposure to extreme heat, using low-quality batteries, or when one of the safety protections fails. Although reputable manufacturers subject their products to rigorous safety testing, incidents can still occur unexpectedly. Even giants like Apple have faced issues with overheating and exploding batteries. That's why every device powered by Lithium-Ion batteries incorporates safety protections, such as smart safety circuits that monitor voltage and temperature to avert disasters. Unfortunately, not all safety circuits are created equal.

In a previous review, we explored rechargeable Power Banks that relied on Lithium-Ion batteries. These models are popular due to their larger capacity, which customers naturally gravitate toward. However, choosing the wrong one, especially those found in the bargain bins of China, can invite potential disasters. Today, we're examining a different type of Power Bank that offers a much safer battery chemistry compared to Lithium-Ion/Polymer options. It's a chance for you to recharge your devices while feeling more secure throughout the process.

Maha Energy has come up with a compact USB Power Bank that distinguishes itself by using four rechargeable NiMH (Nickel Metal Hydride) batteries instead of the typical Lithium-Ion ones commonly found in such devices. But here's the exciting part: Maha Energy has made it compatible with any AA or AAA size NiMH batteries available on the market. They've taken an open-minded and creative approach by not restricting users to a closed system. Moreover, to sweeten the deal, Maha includes four of their highly sought-after IMEDION Low Self Discharge (LSD) 2400mAh AA batteries in the package, allowing you to get up and running in no time.

Maha Energy's IMEDION batteries boast the latest advancements in NiMH technology, ensuring that they retain up to 85% of their capacity even after one year of storage. If you're familiar with Eneloop batteries from Sanyo, think of IMEDIONS as Maha's response to them. Regular non-LSD batteries tend to self-discharge and lose their capacity by up to 1% each day when not in use.

Without further delay, let's dive into 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 arrives in a simple corrugated box with a modest slip-on cover that partially conceals the contents. It lacks the extravagant packaging I've seen in previous Maha Energy products, such as the MH-C9000 Charger-Analyzer I reviewed back in 2010. However, the emphasis on packaging doesn't necessarily reflect the quality of the product itself. Let's hope the MH-C204U receives the same level of attention to detail.

The front cover features a prominent image of the product, while the back provides a brief overview of the charger/USB power bank's rear panel and highlights its main features. These include the ability to charge 2 or 4 AA/AAA NiMH batteries at a rate of 450mAh, its dual functionality as a battery charger and USB power bank (with a 5V/1A output), the convenience of recharging via the supplied micro USB cable and micro USB AC charger adapter, and the integration of an intelligent microprocessor that utilizes the "-deltaV" algorithm for charge termination. The product also comes with a 1-year warranty.

Upon opening the box, the Maha MH-C204U charger power bank reveals itself in all its glory. In terms of size, it is slightly larger than a credit card, perfectly matching the dimensions of my wallet. I would have appreciated the product being wrapped in protective plastic, as it appeared dusty straight out of the box and had acquired some minor scratches from shifting against the cardboard packaging. The glossy exterior finish tends to attract dust and lint, which can be bothersome for some of us. Additionally, fingerprints become instantly visible upon handling the device. Maha could have improved this aspect by either including a soft microfiber cloth in the package or opting for a matte finish from the beginning.

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

When I held the Maha MH-C204U in my hands, I immediately noticed a distinct difference compared to the Maha MH-C9000 Charger-Analyzer. The plastic used in the MH-C204U charger power bank fails to match the robust and sturdy feel of its more expensive counterpart with its matte finish. The MH-C204U charger power bank gives off a somewhat toy-like impression due to its noticeably thinner plastic construction compared to the MH-C9000 Charger-Analyzer. Speaking of which, I must commend the MH-C9000 Charger-Analyzer I reviewed back in 2010, as it has proven to be a stellar product that is still functioning flawlessly to this day (without any incidents up until late 2015). Its appearance remains unchanged with its durable matte finish and thicker plastic. It's truly impressive considering I've used it regularly for nearly five years.

With the MH-C204U, it's clear that a tighter budget was allocated to its manufacturing. However, overall, it's not as bad as my initial description may suggest. The fit and finish are still present, and the device does not feel flimsy or exhibit excessive flexing.

Considering the budget constraints, the exterior quality is quite decent. My only wish is that Maha Energy had opted for a matte finish instead. After just a week of throwing it into my bag and traveling with it, the device already shows signs of wear with swirls, scratches, and small nicks. Additionally, I felt that Maha Energy missed an opportunity to inject some fun and personality into the design, as it remains very basic. It would have been nice to see a range of color options, but unfortunately, the MH-C204U is only available in black.


In terms of design, the Maha MH-C204U charger power bank embraces simplicity to the fullest extent, which some may find rather mundane. However, it does feature curved edges, adding a touch of flair to its overall appearance. On the front of the device, you'll find the Maha POWEREX logo, positioned just above two LEDs. To the left of the logo, there's a plastic chrome strip that serves as the battery compartment door, allowing easy access. Additionally, there's a thumb indentation intended to assist in opening and closing the compartment door effortlessly. However, I must admit that the glossy and slippery nature of the surface makes it somewhat challenging to utilize the thumb indentation effectively. It would have been more practical if the thumb indentation were located just below the chrome strip, where it could provide better grip.


Flipping the charger power bank to its bottom side, you'll notice the presence of four rubber feet. These feet effectively serve their purpose by providing stability and preventing the Maha MH-C204U charger power bank from slipping or accidentally falling on various surfaces. Additionally, there's a sticker on the bottom that discloses the product's origin, stating that it is made in Taiwan. The sticker also provides important specifications, indicating that the charger input operates at 5V/1.2A, while the charger output is a USB port delivering 5V/1A.

Back Panel

On the back panel of the Maha MH-C204U charger power bank, we encounter a series of elements from left to right. First, there is a red power LED light that indicates the charging status. Next, we find a single USB port, enabling the device to function as a power bank. Adjacent to the USB port, there is an ON/OFF switch, allowing users to control the power flow. Lastly, we have a micro USB port used for recharging the batteries when they are depleted.

While it may seem like nitpicking, I would personally have preferred a pushbutton instead of the power ON/OFF switch. It's possible that the decision to use a switch instead of a push-button was influenced by cost considerations, as switches tend to be more affordable. However, I've noticed that when utilizing the power bank capabilities and the USB port is in use, turning off the switch can sometimes be challenging. For instance, if I have a USB LED flashlight connected that is slightly wider than the USB port itself, the proximity of the switch to the USB device makes it difficult to reach and turn off the power. It would have been more convenient if the power switch were positioned slightly farther away from the USB port, considering the available space on the back panel. This way, I wouldn't have to rely on my fingernails or resort to using a pen or similar object to manipulate the switch. Of course, this issue doesn't always occur and can be avoided when using a regular-sized connector.

In the long run, a push-button would have been a better design choice. However, it's important to note that this issue is not persistent and will not arise when using a connector of regular size.


When you open the battery compartment door of the Maha MH-C204U charger power bank, you'll find that the interior has a matte finish and everything is clearly labeled with symbols, signs, and text. By default, the setup is configured to work with AA batteries. However, near the top of the positive poles, there are tabs that can be pulled down to convert the charging bay to accommodate smaller AAA batteries. These tabs provide a sturdy feel and produce an audible click when pulled all the way down and locked into place. To revert back to the AA charging bay setup, simply lift the tabs and lock them back into place, then close the battery compartment door.

Although the battery compartment door can be completely removed as it attaches to plastic rails on the bottom of the charger power bank, it can be slightly awkward to put back on and secure into place. If you frequently swap and recharge batteries, it may be more convenient to remove the battery compartment door entirely, as it can obstruct and interfere with the bottom of the unit. Additionally, removing the door allows the batteries to passively cool down, as they are situated closely together.

The Maha MH-C204U charger power bank's battery bay is divided into two sections to support recharging in either a 2-battery or 4-battery configuration. There are two independent charging circuits, one on the left side and one on the right side. It is not possible to charge only a single battery at a time, as the charger requires a minimum of 2 batteries to operate in either bay. You can mix and match AA and AAA batteries and have a setup of 2 AA and 2 AAA batteries charging simultaneously, although it may not be necessary since the package includes 4 AA IMEDION LSD batteries. The user's manual advises against mixing and matching, but as long as you do so on separate bays (left or right), there shouldn't be any issues. However, I would advise against mixing and matching batteries in the same bay.

Once the batteries are in place and the recharging process begins, the two LEDs located below and to the left of the POWEREX logo on the front of the charger will turn on and cycle from red to green three times. This indicates that the charger is analyzing the battery state and condition. After the analysis, the LEDs will remain solid red during the charging process. The charger operates at a charge rate of 450mA, so it's not considered a quick charger. It will take approximately 4-5 hours to fully recharge the included batteries from a discharged state. The left LED corresponds to the two batteries on the left side of the battery bay, while the right LED indicates the charge status of the two batteries on the right side. Once the batteries are fully recharged, a solid green LED will be displayed. It is advisable to remove the batteries from the charger as soon as you see the green lights, as the charging circuit will continue to trickle charge them at a small rate of 50mA. If the charger is blinking constantly between red and green LED lights, it signifies that the battery (or both batteries) in that particular bay is defective or has high impedance, and can no longer be recharged.

USB Charger Doctor

While the user's manual may suggest leaving the batteries on the charger overnight for optimal activation, I would like to offer an alternative perspective. It is essential to prioritize safety and exercise caution when charging batteries.

Leaving batteries unattended while charging, particularly for prolonged periods such as overnight, can pose certain risks. Concerns arise regarding the possibility of overcharging, which may lead to battery damage or venting. It is worth noting that while NiMH batteries are generally safer than lithium-ion or polymer batteries, there is still a small chance of venting during the charging process, especially if using lower-quality chargers.

To ensure a safer charging experience, it is advisable to refrain from leaving the batteries and charger unattended. Once the charging process is complete, promptly remove or unplug the batteries to minimize any potential risks. By adopting these precautions, you can further mitigate the possibility of adverse events and promote a safer charging environment. Safety should always be a top priority when dealing with battery charging and usage.


The process of accessing the internal components of the MH-C204U charger power bank is straightforward. By removing the four rubber feet located at the bottom of the device and unscrewing the Phillips screws, the device can be opened up for further examination.

In comparison to its higher-end counterpart, the Maha Energy MH-C9000 Charger-Analyzer, which I reviewed in 2010, the internal construction of the MH-C204U displays some differences. The MH-C9000 charger-analyzer boasted a professional soldering job, characterized by flawless connections likely made by an automated machine. Additionally, the MH-C9000 featured a more intricate PCB design with traces that were meticulously routed between the layers of the circuit board.

It's important to note that the MH-C9000 charger-analyzer, being a more expensive and complex device, likely received greater attention and care during its manufacturing process. The additional features and functionalities of the MH-C9000 may have warranted a higher level of precision and quality in its construction.


Upon opening the MH-C204U charger power bank, it becomes evident that the construction quality and soldering work are noticeably different compared to the higher-end MH-C9000 Charger-Analyzer. As previously mentioned, it is apparent that the MH-C204U was manufactured with strict budget constraints in mind.

Examining the PCB and soldering in detail, the differences between the MH-C204U and MH-C9000 are stark. The soldering on the MH-C204U appears to be done by hand and lacks the precision and flawless connections found in the MH-C9000. The traces on the PCB also appear to be hand soldered, and the overall cleanliness is compromised by the presence of flux residue and other debris. In various areas, the soldering job looks amateurish, while in others, it falls short of acceptable standards, with some solder points appearing to be poorly executed. Additionally, there are instances where the traces are too close to overlapping or making unintended connections.

This inconsistency throughout the soldering and PCB raises concerns about the long-term durability and reliability of the MH-C204U. There is a higher likelihood of cracked or cold solder joints developing over time, potentially affecting the device's performance and longevity. While the charger power bank does function, the subpar soldering work observed is far from the quality standard expected from Maha products. It is disappointing to see such inconsistencies and compromises, and it suggests that Maha could have invested a bit more in ensuring higher manufacturing standards for the MH-C204U.


After inspecting the PCB and soldering of the MH-C204U charger power bank, I decided to take the extra step of cleaning the board before reassembling the device. Using a flux remover and a toothbrush, I carefully scrubbed away the residue and dirt, ensuring that the PCB appeared much cleaner than before. While this cleaning process greatly improved the overall appearance of the board, it should be noted that the soldering job itself remained unchanged.

Although I opted not to spend time fixing the soldering issues, I wanted to ensure that the PCB was as clean as possible to maintain optimal functionality and minimize the risk of any contaminants causing future problems. By giving the PCB a thorough cleaning, I aimed to enhance the overall reliability and performance of the charger power bank, despite the shortcomings in the soldering work.

Where Can I Buy One? And for How Much?

Currently, the Maha Energy MH-C204U Compact USB AA/AAA Charger Power Bank is available for purchase on Amazon at a discounted price of $26.70 USD. The product is being sold directly by, ensuring a reliable and trustworthy transaction.

I appreciate Amazon for its exceptional speed, reliability, and commitment to honesty. Their return policy is excellent, and they have even demonstrated their integrity by refunding me the excess duty costs they mistakenly charged. This kind of transparency is rare to find, as many companies would not disclose such errors. If you're considering buying the Maha Energy MH-C204U or any other product, I kindly ask you to consider using our Amazon link provided above. Your support would be greatly appreciated. Thank you.


Some Amazon Deals That May Interest You!


After extensively using the Maha Energy MH-C204U compact USB AA/AAA charger power bank for approximately five (5) months, I am pleased to report that I haven't encountered any major issues related to its recharging and power bank capabilities. However, it's important to note that this product is not perfect. The plastic exterior feels cheap and toy-like, easily getting scratched and attracting fingerprints and dust due to its glossy finish. Additionally, its charging speed is relatively slow at only 450mA. I also have reservations about the subpar soldering job on the PCB, which is uncharacteristic of Maha Energy's usual quality.

If these shortcomings are acceptable to you, then you may consider purchasing it. However, considering the $29.99USD price tag, I regretfully have to suggest looking for alternatives. It disappoints me to reach this conclusion as I had higher expectations for Maha Energy and did not anticipate such compromises. The soldering quality, in particular, raises concerns and does not instill confidence. In my opinion, this product would be more appropriately priced around $9.99. The only redeeming aspect of this package is the inclusion of IMEDION low self-discharge batteries.