Miisso 6000mAh Ultra Slim Review

The Miisso 6000mAh Ultra Slim weighs just 4.0 ounces, making it one of the lightest in our lineup. It comes with two integrated cables (lightning and USB-C) as well as a USB-A port (outputting 5 V/2.0 A) and can be charged with a USB-C or micro USB cable.

Performance Comparison

Portability

If you need a portable charger, it's because you're bringing along other electronics that may die when you're not close to a wall outlet for easy charging. As these small batteries are already an additional item to bring, their portability is an important part of their overall convenience and usefulness. The Miisso Ultra Slim is our favorite model in this area. It weighs just 4.0 ounces, making it one of the lightest models we tested — and it feels noticeably light, even compared to other smaller chargers in our lineup. It's 4.13 inches long and 2.63 inches wide — a standard credit card is 3.375 inches long and 2.125 inches wide. And it's just half an inch thick.

The Miisso Ultra Slim is not only small, thin, and light but has other features we like for portability, like integrated cables. From one side, a lightning cable pops out to charge any handheld Apple device you may have. On the other side, a USB-C cable covers a ton of other possible devices you may be traveling with. Need to charge something with a micro USB? No problem — a USB-A outlet on top lets you plug in any other cable you may need to charge your electronics while traveling. This is also the best option for those who like to rock their phone and the battery charging it all in one pants pocket. And with integrated cables, the two are kept close, without any loose wires tripping you up or getting caught.

Charging Efficiency

The Miisso Ultra Slim isn't the most efficient power block we tested. We ran multiple types of tests to find out how much juice this 6000 mAh model actually puts out. We hooked it up to a multimeter to drain the battery and we used it to fully charge a brand new iPhone 13 (from dead) as many times as possible. After running each test several times, we found that the Miisso is roughly 51% efficient — not horrible for portable chargers, but far from impressive.

While the Miisso isn't the best model for several days in a row of charging up your phone overnight, it still packs plenty of juice for those moments when you find yourself on a 7 hour flight with no outlet or staying out late with friends and trying to catch an Uber home with 4% battery. The number and types of charging ports also factor into our scoring of each model's charging efficiency and the Miisso Ultra Slim has a lot of options for such a small device. We think it's also worth noting that all three charging ports (the lightning cable, the USB-C cable, and the USB-A port) output a full 5 V/2.1 A — many other models only offer a single port charging at that speed while subsequent ports output just 1 A, making it take longer to charge up your devices.

Added Convenience

There are so many extra features found on portable chargers that can add to your overall enjoyment of using them in specific situations. But some offer more universal convenience, and we rated the models we tested more heavily on these features. One such feature is the ability to charge multiple devices at the same time, which the Miisso Ultra Slim, with its 3 ports, is very capable of. Two of those charging options have built-in cables, adding further convenience to this model — not only do you not have to remember to bring the right cables, when using these flat cables built into the sides of the charger, but it also maintains a better connection than just a USB cable plugged into the top. This adds extra security to your charging, as you don't have to keep checking both ends of the cable as it bounces around in your bag. And in case you don't already own a micro USB cable, it comes with one — great for recharging the battery itself and doubles as a third charging option for the USB-A output port.

The Miisso doesn't come with some of the more trivial extras — like a flashlight or an integrated wall charger — but we docked it fewer points for lacking these minor details. It does have a battery indicator (most do) that lights up the number of quarters of a ring which corresponds to how much juice is left in the charger. That indicator stays on the whole time it's charging so you can easily see when your device is getting power. It also begins charging as soon as you plug in a device; no need to remember to press a power button to start that process. This small capacity charger doesn't support power hungry devices, as 2.1 A is typically not enough for most tablets (2.4 A is recommended). However, it does support quick charging, which anyone with a dead phone and places to be will appreciate.

Recharge Time

With a smaller capacity than most other portable chargers in our lineup, we expect the Miisso Ultra Slim to recharge more quickly and it doesn't disappoint. From completely dead, we were able to fully recharge this battery in just 2 hours and 45 minutes using a standard 5 V/2.1 A (think your typical USB power block) and the micro USB cable it comes with. With a power block that puts out even more energy — like those used for tablets or quick charging — the USB-C input lets you juice the Miisso up even faster.

Though these times at first seem obvious — a 6000 mAh battery should charge faster than a 10000 mAh battery — the Miisso Ultra Slim still recharges faster than most others when we broke down recharge time by the amount of power being recharged. We appreciate the added convenience of this quick turnaround time, especially when stuck in an airport during long layovers or in the office for long workdays. We're also big fans of the dual input options, which give you choices for how you want to recharge. This both makes it easier to make sure you've brought the right cables and gives that handy option for a quick recharge if you've got the right power block for the job.

Should You Buy the Miisso Ultra Slim?

This small, lightweight, thin model is a great choice for folks who always find themselves on the go with multiple types of devices and limited space. It's convenient to use and has a reasonable amount of power for plenty of extra phone juice or partial charges of multiple gadgets. If you need to charge a tablet or have the power to last through days of no electricity, this low capacity model may not be enough. But for most folks who just need a no-brainer option for daily use, the Miisso Ultra Slim is an excellent choice.

What Other Portable Chargers Should You Consider?

The Miisso Ultra Slim is a great compromise of portability and usefulness. If you need more juice than this small capacity model can handle, the INIU Portable Charger 10000 is our favorite option for continuous use over days of electricity needs. On the other hand, if you're heading out and need to keep things even smaller, the Clutch V2 is the smallest and thinnest model we tested and fits easily into your clutch without requiring any cables to give your smartphone enough power for that final Lyft ride home at the end of the night. But for a slightly larger charger, we love the extra capacity and convenience of the Miisso Ultra Slim.