I made a couple of interesting discoveries at CES 2022, despite the in-person show being scaled back due to the pandemic. One of those discoveries was Rolling Square, a Switzerland-based company striving to innovate for the tech minimalist. Their booth turned my head, intriguing me with their assortment of cabling options, power banks and other tech solutions. We got to check out the inCharge X, which Rolling Square charmingly dubs as the “100W Swiss Army Knife of Cables”. The inCharge X is the 2020 iteration of a product that started the ball rolling for Rolling Square back in 2014. It is a nifty keyring cable that is a USB-C, USB-A, Lightning, and micro-USB cable, all in one. It supports fast charging up to 100W and a data transfer rate of up to 480 Mbps / 60 MBps.
The inCharge X is easily one of the smallest and most practical accessories I did not know I wanted until now. If Rolling Square can do this much with such a small form factor cable, I was surely curious to see what they can do in the realm of portable power. At CES 2024, I was introduced to the Tau 2. The Tau 2 is a miniature power bank that can be attached to your key chain while being armed with three connectivity options.
Tau 2 Power Bank Specs
| Capacity: | 2000 mAh |
| Size: | 63x43x19mm / 2.5×1.7×0.7 in |
| Weight: | 50 gr / 1.7 oz |
| Holdable Weight: | 690 gr / 24 oz |
| Connectivity: | Lightning, USB-C, micro-USB |
A purchase of the Tau 2 power bank comes with a Tau 2 charging dock and a double-sided adhesive tape.
Build, Features, and Performance
The Tau 2 is a miniature power bank that is the size of a key fob. Making use of its size, the Tau 2 features a key clip for adding it to your key ring. It has a battery capacity of 2000 mAh and houses three connectivity options: lightning, USB-C, and micro-USB. If you are wondering how three connectivity options are available from only two cables, the answer lies in Rolling Square’s dual connector. This dual connector is uniquely designed to fit in both micro-USB and lightning port slots while the Tau 2’s other cable houses the USB-C connector.
The Tau 2 recharges its battery via its proprietary dock. The dock itself is space-conscious, being easily arrangeable atop of any surface or affixed to a wall. Setup is easy. Simply use the included adhesive tape to stick the dock to the surface of your choice. The tape is pretty forgiving, allowing you to peel and reapply the dock to different surfaces as needed.
However, the Tau 2’s USB-C cable can also be used to recharge the battery directly, without having to rely on the dock. The power bank’s Tau logo is actually a touch control, where four taps allow you to set the battery to input mode. You can then simply connect the USB-C cable to a power source and the Tau 2 will begin to recharge accordingly.
Going further, the Tau 2 can also provide passthrough charging, using the USB-C cable to receive a charge while the Lightning/micro-USB cable recharges the device connected to its end. It can also charge two devices simultaneously, with each cable connected to their own separate device.
Right off the bat, the Tau 2 is impressive with its super compact frame and highly portable design. This is as small as power banks get, sporting a size that is easy to slip into even the smallest of pockets. So, designing it as a key chain accessory was a very nice touch. When docked, a powerful magnetic connector keeps the Tau 2 in place as it charges. The magnetic connector is strong enough to hold both the Tau 2 and the weight of a respectable number of keys. This allows you to hang the Tau 2 with your keys on the wall of your choice, just as you might normally hang your keys by any door.
The included double-sided adhesive tape is also pretty handy in its own right. On one hand, depending on the surface, you can attach, remove, and replace the Tau 2’s dock as you see fit. Yet on the other hand, the tape is strong enough to hold the dock, the Tau 2, and your keys without slipping off the wall. To be honest, when I first saw Rolling Square’s stock images and YouTube video showcasing this feature, I was a little skeptical. Yet, here is the Tau 2, in its dock, holding up a good number of keys and weight.
Now, let us dive into the meat and potatoes of any power bank, the charging. Even though the Tau 2 sports both USB-C and lightning cables, it does not deal out the sort of “quick charging” that you could normally get with many rechargeable devices today. For example, a Qualcomm Quick Charge adapter and the InCharge X cable mentioned above can give you some impressive rapid-recharge rates. That said, the Tau 2 still gets the job done in a reasonable amount of time.
Here, I took the Tau 2 outside with me for some drinks and plugged it into my Samsung Galaxy Z Fold5, a phone with a 4400 mAh battery. In about an hour and 18 minutes, I was able to get a little over 30% of battery charge from the Tau 2 before it fully depleted. Getting back 30% of battery power into my device while it was still powered on was not bad at all.
The Tau 2’s versatility with its three connection options further raises the power bank’s stock. It is truly ready to help with the emergency power needs of any mobile device out today.
The Tau 2’s dock took about an hour and 50 minutes to recharge the Tau 2 from 0% to 100%. While the dock itself is very small, chances are that you will leave it at home to charge your Tau 2 overnight. As such, a full recharge in less than two hours felt appropriate.
Final Thoughts
From a power bank this small, around 30% of battery charge for your mobile device is a nice thing to have in a pinch. Not to mention, its three connectivity options make it hard to find a present-day mobile device that it cannot recharge. Expanding its versitility is its ability to recharge itself without having to depend on its proprietary dock.
Considering the Tau 2’s exceptional portability, versatility, and the fact that this power bank is only $39.90, I consider the Tau 2 to be the perfect gift for either yourself or any techie on the go. If you are curious about checking out the Tau 2 for yourself, you can do so by clicking here.
Also, if you are curious about the “100W Swiss Army Knife of Cables”, you can also check out the inCharge X by clicking here.
† We were provided a Rolling Square Tau 2 power bank for review purposes and were not compensated for this review.
