The Storm 2 Slim is a powerful backup battery from Shargeek which has a couple of unique features that definitely make it stand out from the crowd. It features an IPS display to show you the behind-the-scenes numbers of the battery pack, a 20,000mAh capacity, and 100W of power to charge every device from your smartwatch to your laptop, and all at once.

Its most notable feature, however, is the transparent outer shell that gives you a window into the battery for an awesome view of the circuit board and other internals.

Without a doubt, the Shargeek Storm 2 Slim (and it’s big brother the Storm 2) are some of the coolest looking backup batteries on the market.

It has a small profile so that it’s easy to carry around in a pocket and it comes with a carrying pouch as well as a high quality USB-C to USB-C charging cable. You can get the Storm 2 Slim for $199.00 on the Shargeek website.

Convenient Display

The Energy Management OS of the Storm 2 and Storm 2 Slim has some very interesting features. A small IPS display with a button allows you to interact with the system. The top GUI displays tons of information about the status of the battery pack such as input/output wattage, voltage, and current.

You can also see the temperature, power percentage, voltage, and running time. Using the button provides access to additional features in the settings such as Output Configuration, Battery Information, Temperature Units, System Running Time reset, display configuration, and more. 

If you opt for the Slim battery pack, you will only have one USB-A and one USB-C port that can be used simultaneously; however, the Storm 2 pack gives you a couple of additional ports. These include a DC in/out and an additional USB-C port. The DC in/out port will also give you an additional software feature that allows you to make adjustments to the voltage of output in increments of 0.1 V.

Additionally, the Energy Management OS gives you some peace of mind with safety measures in place to ensure the proper performance of the battery. Warnings will display on the screen if the battery overheats or is too cold, or when the DC output mode is on (so that the user knows not to plug in any input).

Capacity and Power

As far as capacity goes, 20,000mAh is plentiful, especially considering the size of the Storm 2 Slim. It features a 100W port and 30W port so that you can charge with up to 130W of power, only limited by the connections necessary for the job.

In my personal tests, the battery was able to charge my phone twice overnight before it needed a refill, which is way less than expected. Given the 5,000mAh battery capacity of my smartphone, I expected around 3-4 full charges. It is possible that having the phone remain plugged in for the rest of the night drastically reduced that.

It took about 1.5 hours to charge my phone each time. Over about a week of no use, the battery level only dropped 1%, so I think it’s fair to say that it holds up well to long periods of dormancy.


In the end, the Shargeek Storm 2 and Storm 2 Slim are a very unique and interesting pair of backup batteries. The fireproof clear outside case gives them an awesome aesthetic look sitting on your desk.

If you want, or need, more output ports to charge devices then I would definitely suggest the Storm 2 rather over the Slim option. Gaining those two additional output ports, as well as the software feature which gives you configuration options of the DC port.

The 20,000mAh capacity is generous and helpful for most uses, but perhaps be cautious about leaving your phone plugged in overnight. The price is a bit high, in my opinion, as you’re paying a lot for the “cool factor” with this product, but it’s unlike any other charger I’ve used.

Learn more about the Shargeek Storm 2 Slim at the manufacturer’s website where you can purchase one for about $200.

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