ZMI 20 QB826G Power Bank International Version Review - 210W 25000mAh high-power portable power solution

• Disclaimer: sample used is provided by Xiaomi, Zmi. Mostly Melbourne as reseller is affiliated with Xiaomi/Zmi and has vested interest. This article does not represent an advice of purchase.
• Product Link: mostlymelbourne.com | Amazon Link

Original article https://www.chongdiantou.com/archives/121136.html

Posted by @gleaxy

Introduction

Back in October 2020, the ZMI 20 power bank QB826 was launched with an impressive 200W maximum output, stunning users with its capabilities. Besides supporting 100W PD output, it also featured additional support for Xiaomi's 120W proprietary fast charging protocol, making it an instant favorite among Xiaomi smartphone users.

Recently, Chongdiantou received the international version of the ZMI 20 power bank. You might wonder, "Why would a power bank have different international and domestic versions?" Here's a small spoiler: its maximum output power has been upgraded to 210W. Can this additional 10W total output actually make a noticeable difference in real-world usage? Let's investigate.

Product Overview

The packaging includes an outer cardboard box to protect the product during shipping, with a label displaying product specifications.

Key Specifications:

Opening the box, the international version of the ZMI 20 power bank's packaging is essentially identical to the domestic version, with only the 210W output label differing slightly.

The package contents include the power bank unit, user manual, a USB-C to USB-C data cable, and a USB-C to USB-A data cable.

The power bank features a silver painted exterior with a black matte frame, giving it a professional business appearance. The ZMI logo is printed on the top left corner, while the 210W power rating is displayed on the bottom right.

The CD-textured power button and LED display are positioned on the side. The fit and finish are quite good, with precise assembly and no obvious gaps.

As mentioned earlier in the specifications, the international version's USB-A port isn't labeled as supporting 6A output, possibly to make it easier for consumers in different markets to understand.

The unit has a 2C1A port configuration, with two USB-C ports supporting 100W and 45W input power, respectively. The USB-A port has additional contact pins, indicating it supports Xiaomi's fast charging protocol—otherwise, the USB-A port couldn't reach 100W output.

Physical Dimensions:

Length: approximately 188.75mm
Thickness: approximately 27.63mm
Width: approximately 80.42mm
Weight: approximately 585.2g

The included USB-C to USB-C cable features high-quality connectors with a glossy finish. The cable incorporates an E-Marker chip, supporting 100W charging with USB 2.0 data transfer specifications. Its length is approximately 53cm.

The package also includes a USB-A to USB-C cable, approximately 100cm in length. The USB-A connector has additional pins for protocol recognition.

Product Comparison

We dug out our old domestic version of the ZMI 20 power bank for comparison. The most obvious difference is the 200W vs. 210W labeling on the front.

The button and LED display are identical between versions. The main difference lies in the USB-A port specifications: the international version lists output levels as 5V2.4A, 9V3A, 12V3A, 15V3A, 20V5A, while the domestic version lists 5V2.4A, 9V2.23A, 12V1.67A, 20V6A. But do these specifications actually translate to real-world differences in testing?

The port interface also differs slightly, with the domestic version having more detailed power output and voltage specifications printed near each port.

Performance Testing

After covering the appearance and compatibility of the international version of the ZMI 20 power bank, let's move to testing, examining protocols, PDO capabilities, and compatibility aspects to give you a comprehensive understanding of this power bank.

Protocol Testing

This testing module primarily examines the fast charging protocols supported by the power bank, allowing users to match output devices for the best fast charging experience.

Using ChargerLAB's POWER-Z KT002 tester to read the USB-C1 fast charging protocols, we found it supports Apple 2.4A, QC2.0, QC3.0, QC4+, AFC, FCP, PD3.0, and PPS charging protocols.

For PDO messaging, it supports 5V3A, 9V3A, 12V3A, 15V3A, and 20V5A fixed voltage levels, plus 5V-11V5A and 5V-20V5A PPS voltage ranges, providing excellent device compatibility.Similarly, USB-C2 supports Apple 2.4A, QC2.0, QC3.0, QC4+, AFC, FCP, PD3.0, and PPS charging protocols.

For PDO messaging, USB-C2 supports 5V3A, 9V3A, 12V3A, 15V3A, and 20V2.25A fixed voltage levels, plus 5V-11V4A and 5V-20V2.25A PPS voltage ranges.

The USB-A port supports Apple 2.4A, QC2.0, QC3.0, and FCP charging protocols. However, when paired with the included A2C charging cable, this port also supports 100W PD output. Our tests confirmed it matches the domestic version and supports 6A high current output, with a maximum power of 126W in PPS mode.

Compatibility Testing

The compatibility test allows us to clearly understand how the power bank charges various devices. Chongdiantou tested dozens of devices with the power bank to present real-world testing data.

Some examples of the USB-C1 port charging performance:

• Redmi Note 11 Pro: approximately 17.11V 4.88A 83.57W
• Black Shark 4S: approximately 16.82V 4.88A 82.24W
• iPad Pro: approximately 14.9V 1.95A 29.19W
• MacBook Pro 16: approximately 19.76V 4.61A 91.2W
• Nintendo Switch Dock: approximately 5.33W (successfully triggering TV mode)
  
  

The data for all tested devices was compiled into a table. Nearly all models could enter fast charging mode, demonstrating excellent compatibility.

Similarly, we tested the USB-A port with the included A2C cable:

• Redmi Note 11 Pro: approximately 17.32V 5.15A 89.31W
• Xiaomi 11 Pro: approximately 8.8V 4.91A 43.23W
• Black Shark 4S: approximately 17.72V 5.78A 102.4W
• MacBook Pro 16: approximately 19.63V 4.3A 84.61W
• Nintendo Switch Dock: approximately 4.57W (successfully triggering TV mode)

Only when using adapters to charge iPhones was the performance abnormal, due to requiring the included A2C cable to trigger the PD protocol.

USB-C2 port was also tested with various devices, with a maximum output power of approximately 45W. All tested models performed normally.

Multi-Device Charging Tests:

We conducted several multi-device charging tests to evaluate the power bank's performance under load:

• Using two USB-C ports to charge MacBook Air and MacBook Pro 16: 28.67W and 91.06W respectively, for a total of approximately 119.73W
• Charging Redmi Note 11 Pro, MacBook Air, and MacBook Pro 16 simultaneously: 53.56W, 36.76W, and 90.44W respectively, for a total of approximately 180.76W
• USB-C1 input while using USB-C2 to charge MacBook Pro 16: 39.46W input, 35.59W output
• USB-C2 input while using USB-C1 to charge MacBook Pro 16: 44.73W input, 89.16W output
• USB-C1 input while both USB-C2 and USB-A port output: 44.71W input, outputs of 89.6W (MacBook Pro 16) and 53.56W (Redmi Note 11 Pro+), for a total of approximately 143.16W
• USB-C2 input while both USB-C1 and USB-A port output: 64.54W input, outputs of 39.56W (MacBook Pro 16) and 53.76W (Redmi Note 11 Pro+), for a total of approximately 93.32W
• USB-C1 input while USB-A port output: 65.68W input, 53.89W output (Redmi Note 11 Pro+)
• USB-C2 input while USB-A port output: 44.61W input, 53.96W output (Redmi Note 11 Pro+)

Pass-Through Charging Capabilities

One of the most practical features of the ZMI 20 Power Bank is its pass-through charging capability, which allows you to charge the power bank itself while simultaneously charging other devices. This functionality is particularly useful when you have limited access to wall outlets but need to charge multiple devices.

We conducted comprehensive tests of the pass-through charging functionality using different input/output port combinations:

* In these cases, output power exceeds input power because the power bank is supplementing the input power with its own stored energy.

Our testing revealed several important characteristics of the pass-through charging functionality:

• High efficiency direct pass-through: When output power is less than input power, the efficiency is quite high (82-90%), meaning minimal energy is lost during the conversion.
• Power supplementation: When connected devices require more power than is being input, the power bank intelligently supplements the additional power from its internal battery.
• Priority to output: The power bank prioritizes powering connected devices over charging itself, ensuring your devices charge at their optimal speeds.
• USB-C1 superiority: The USB-C1 port provides better performance for high-power devices when in pass-through mode.

This makes the ZMI 20 Power Bank particularly valuable for travelers who may have limited access to wall outlets but need to charge multiple devices. You can effectively use a single power outlet to charge your power bank overnight while simultaneously charging your laptop, phone, or other devices.

Input Charging Tests:

• Apple 140W PD charger to USB-C1 port: approximately 20.31V 4.29A 87.31W
• Apple 140W PD charger to USB-C2 port: approximately 20.4V 2.18A 44.59W
• Xiaomi 120W charger to USB-C1 port: approximately 19.75V 3.07A 60.77W
• Xiaomi 120W charger to USB-C2 port: approximately 19.83V 2.2A 43.66W

Input Full Cycle Testing

For self-charging, the ZMI 20 power bank international version supports 100W PD fast charging input, so we conducted a full charging cycle test.

First, using a 100W PD charger through USB-C1 (100W input) to charge the power bank, the entire process went through four stages and completed in 1 hour and 44 minutes.

When using a 45W PD charger to charge the power bank, it took 2 hours and 23 minutes to fully charge, somewhat longer than with the 100W charger. If you want to recharge your power bank quickly, the 100W experience is best.

Output Efficiency Testing

The power bank's actual output efficiency varies at different power levels due to voltage conversion within the battery. We tested the power bank's output efficiency at different output levels.

Results of continuous discharge tests at different power levels:

• 5V3A output: 5 hours 5 minutes runtime, 76.4864Wh actual output, efficiency approximately 84.32%
• 9V3A (27W) output: 2 hours 54 minutes runtime, 77.7181Wh actual output, efficiency approximately 85.68%
• 12V3A (36W) output: 2 hours 11 minutes runtime, 78.1553Wh actual output, efficiency approximately 86.16%
• 15V3A (45W) output: 1 hour 44 minutes runtime, 78.0164Wh actual output, efficiency approximately 86.01%
• 20V5A (100W) output: 43 minutes runtime, 72.2836Wh actual output, efficiency approximately 79.69%

These tests were conducted under extreme conditions, with the power bank maintaining constant power output. In daily use, the efficiency would likely be higher than shown in testing, as the charging power typically decreases as device battery level increases.

Thermal Testing

We tested the thermal management of the ZMI 20 power bank international version by running it at 20V5A 100W power continuously for half an hour, then capturing the surface temperature using a thermal imaging camera. Testing was conducted inside a climate-controlled chamber at 25°C.

After continuous 100W full-load output for half an hour, the maximum surface temperature recorded was 47.6°C on one side and 41.4°C on the other side.

Conclusion

After extensive testing, we found no significant differences between the domestic and international versions of this power bank apart from the printed specifications. Both versions have identical performance in terms of form factor, capacity, and protocols. The international version may not explicitly state the 6A maximum current to simplify things for overseas consumers—it's essentially hiding its capabilities.