[General Accessories] vectron:
This is a Review of Xiaomi Mi 20000 mAh dual external battery.

After a few of my recent external batteries reviews I was asked if/when am I going to review the latest offering from Xiaomi, and in general how come I haven't reviewed any of the Mi batteries in the past. It wasn't a matter of not being able to obtain a review sample, but rather a problem with making sure it's a real product from a trusted source. Xiaomi established themselves as one of the top choices in budget-priced gear, and due to their popularity the market is now flooded with knockoffs which sometime hard to tell apart (Xiaomi Pistons is a good example of that). Luckily, <mod snip> is among a few trusted on-line retailers that work directly with Xiaomi distributors, selling their original licensed products. Please keep that in mind, it's not just about the product but also where you buy it to guarantee you're getting a genuine smartphone accessory. And with that "public announcement" out of the way, let's proceed to the review.

Unboxing & Accessories.

The product arrived in a small plain white box, no fancy graphics, no colorful images, just a plain "Mi" and a spec on a side in Chinese. One thing to note, there was an authenticity sticker on the side, what looks like a genuine Xiaomi label. I have enough experience to know these stickers could be duplicated, but in this case it was a real deal because I trust the source I got it from. With minimalistic box you also get a single accessory, a flat usb to micro-usb cable - high quality and very durable, all in white. The whole theme of a plain white box, a simple white battery enclosure, and a simple white usb cable can remind you of "Apple" products - clean and simple.

One missing accessory is usb to usb-c cable. I didn't even know about it until I read on <mod snip>: Mi 20k mAh battery can recharge a new MacBook with usb type-c cable, which makes sense considering it supports 5V 3.6A output. Not sure why they are not advertising it directly because it's a big marketing point for this battery, supporting USB-C technology which has been implemented in the latest MacBook, Google Chromebook Pixel, and Nexus 6P smartphone.

Design.

This minimalistic packaging also caries over to minimalistic plain white design with just a simple "Mi" stamped on the top. Even the label on the back edge is printed in light gray on white which makes it hard to read, and still has a very minimalistic discrete look. But when you take a closer look, you realize there is more to it. To keep the weight down, amazingly enough for 20k mAh battery which is only 338g, Xiaomi used a durable yet environmentally safe combination of PC+ABS plastic with a very fine bumps that make surface anti-skid and anti-scratch. Also, considering such a huge capacity, the dimensions are only 142mm x 73mm x 22 mm, making it among the smallest and the lightest batteries in 20k+ category.

Looking at the top side edge of the battery you will find a single power button which turns on 4-led power indicator to let you know about the remaining storage capacity. I didn't have to press power button to start charging my phone. On the front edge, you will find 2 full size usb Output ports, one micro-usb Input charging port, and 4-leds indicating the remaining capacity or the charging capacity (when re-charging the battery). This 4-led indicator was really a step back for me considering you get only 25% incremental granularity, while I got spoiled by Anker and their 10-led segment indicators. Not really sure why Xiaomi decided to have such a simplistic power indicator, though I'm guessing they probably wanted to keep it small without taking too much room.

Specification and operation.

Obviously this battery wasn't marketed for worldwide release because instructions are all in Chinese, and this is why I do appreciate that Gearbest put as much info as possible in English on their website: Mod Edit by [MENTION=4036181]Darth[/MENTION] : Link to online store removed. . Reading specification and looking through some of the marketing pictures REALLY clears up what's under the hood of this battery.

First of all is a charging micro-usb input to recharge the battery itself. 20,000 mAh is a huge capacity, so forget about using any of your outdated 1A or 1.5A wall chargers. <mod snip> mentions "Support DC 5V / 2A, 9V / 2A, 12V / 1.5A quick recharging" - which is a dead giveaway of QC2.0. Of course, it also supports a regular fast 5V @ 2A charging, but it's nice to have both options. Either way, it will take about 7-8 hours to fully recharge the battery, which is not bad for such high capacity.

In my test, I found with a regular 2A charger I got: 5.33V @ 2.01A

And using Samsung Fast Charger: 6.62V @ 1.63A

When it comes to the charging output of dual USB ports, those support 5.1V with max 3.6A output. That translates into up to 2A for a typical smartphone charging and 3A for USB-C charging. I can't test/verify USB-C since I don't have any devices supporting it yet, but it's a great feature to have in order to future-proof your charger. With usb charging, I was able to confirm it with my Note 4 and it's on par with all of my other 2A chargers, and btw 2A is "max" so the actual charging speed is usually less, where in case of my phone it was about 4.96V @ 1.71A

Another thing to keep in mind is close to 90% efficiency of conversion, considering going from internal battery of Mi to 5V USB port and then through usb cable to your phone and back from 5V micro-usb to internal battery (all this involving a typical 3.7V to 5V conversion with some loses due to efficiency). So realistically you are looking at close to 18k mAh of usable capacity.

Conclusion.

Doesn't take a rocket scientist to realize that I was impressed with this battery :) Due to a lack of access to USB-C devices, I can't test it to its full potential, but I still found it to be among the smallest and the lightest 20,000 mAh batteries I have tested to date. Yeah, the battery is not fancy with aluminum enclosure or better led power indicator, unfortunately you will have to live with a plastic shell and 4-led indicator, but it's still a quality build with a packed functionality, high capacity, full 9S circuit protection, and the big one - priced under $35 shipped free from <mod snip>. But the most important factor is that you can have a piece of mind knowing it's a real Xiaomi product, not a knockoff.