Rolling Square Tau Review

An ultra portable power bank, but is it as convenient as it seems?

Ever been in a situation where you are nowhere near a charger but your phone is on single digits of battery life? Or you’re on a night out and friends need to book taxis but they all have dead phones? We all have, or at least in a situation where we can empathise with those feelings. This is something that the team over at Rolling Square are looking to eliminate. They have created the Tau, a portable power bank that fits right on your keyring. Boasting some features that Rolling Square have wowed us with in other products, as well as some unique design features that set it apart from other power banks on the market. The question is, how useful is this power bank when you put it through its paces?

A small and neat package

 For something to fit on a keychain, size is the first thing that must be considered. Too big and it will make things far too cumbersome to carry around. Too small and it will be difficult to get on and off, and harder to find in a pinch. So how have Rolling Square faced this issue? The Swiss team have put together an extremely neat package, which feels no bigger than a fob that would be used to operate a keyless car for example. The Tau feels right at home on any set of keys. But you may be wondering, with it being so small how does it actually connect to my device? There are two cables that are folded around the edges of the Tau. One has a USB-C connection on the end, the other has their customer Lightning and Mini-USB combo connection (the same as found on the InCharge cables we recently reviewed here). This means that users need not worry about carrying extra cables with them, ensuring the Tau is the all-in-one solution needed for last-minute on-the-go charging.  

Being so small, it only offers a 1400mah battery. Meaning that it’s going to give you at best around 25% of the battery of an iPhone 14 Pro Max back. This isn’t necessarily a bad thing, but don’t expect to be helping multiple friends out with this. But let’s be honest, if the battery capacity was much bigger then the size of the product would be impacted and thus, the entire attraction of it being a power bank that can fit on a keyring would be ruined.

The Tau charges itself off a proprietary magnet connection which is found on the supplied charging dock. This dock is designed to be wall mounted and comes with screws or adhesive strips to affix it to a wall. There is a micro-USB cable supplied with which the dock is supplied its power. An interesting and intuitive design, but not one without some drawbacks…more about that later though. As for colours, the Tau is available in “Charcoal Black”, “Pure White” and “Agave Green”.

As expected from our experience with Rolling Square in the past, the packaging of this product is perfect. Coming in an all-cardboard box with not a slither of single-use plastic to be seen. It really makes a difference to know that smaller companies like Rolling Square are taking a great stance with their environmental impact.  

All charged up…kinda

One glaring design flaw is how the Tau connects to the keyring itself. There’s a small metal hook it which can be pulled up and key a keyring slotted on. On paper this sounds convenient and really great, in practice, however, it’s not as simple. The issue arises when the actual hook that the keys will connect to never seals back to the body of the Tau. This leaves a small gap where the keys can actually slide off. This happened multiple times during testing, often causing panic that the Tau was missing (thankfully it was just on the floor of the car).

Another issue that the Tau faces is in the fragility of the connectors themselves, or more to the point, how the connectors are stored and removed from the Tau. They’re quite tight to remove, which is partially what you would expect, however, if users struggle to wiggle them free they may resort to pulling on the connector itself. This can cause the rubber on the outside to start to wear and peel slightly. A small inconvenience, but one that should be noted.

The final, and major, gripe we faced with the Tau is actually to do with the charging of the device itself. A wall-mounted charger. Sounds neat right? However, the dock that is used to mount the Tau to the wall when it’s not in use is the only way that it can be charged. That means that if you are staying away anywhere and use the Tau on the first day, it will be pretty much useless until you can get back to your home where the wall mount is. It seems like a massive oversight, especially given how Rolling Square have crammed so much into this small device, the fact it has no secondary charging method that can use a normal USB-C or micro-USB really limits our ability to recommend it over the more conventional power banks out there. 

Final thoughts

Given how useful the Tau has been in a pinch, and how it’s actually a neat bit of technology as a whole, all the flaws that we discovered during testing are forcing us to be unable to fully recommend this device. For all the amazing features it boasts, like being able to charge three different connections without the near for adapters. As well as being insanely portable and fitting on any keyring. The fact it can so easily slip off a keyring, as well as having a proprietary connection to charge itself, and not to forget the small mAh capacity of the battery, have to be considered when rating this product. If potential buyers have access to other small, pocket-sized, power banks, do not rush to buy the Tau. Rolling Square has sadly missed the mark with this one, but maybe a second revision in the future could fix a lot of the issues that have been raised.

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