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VK-X battery presentation

Batteries received in Paris – Specifications


Hi everyone 🙂


Lucas here. Hope you are well! We just received more than 1,000 VK-X batteries at the workshop, so I took some time to write this small article and present it. We are available to answer your questions.


A unique battery


The VK-X battery is unique. We could have used standard batteries that exist on the market, which, considering the very limited available space inside the cup, would have highly impacted our battery life duration (a battery capacity is directly connected to its size). Indeed, the standard fitting batteries we found had a 750 mAh (mAh = Milliamp-Hours) capacity. By designing our own battery, we increased its capacity to 950 mAh, which was a  noticeable +26% improvement.



Our custom battery perfectly fits our cup,
thus maximizing its size and capacity.






You will find below the full battery specification list. Please note that the estimated duration will be confirmed after we finished our tests *

  • Rechargeable lithium-ion battery
  • Capacity: 950 mAh
  • Up to 20 hours with Bluetooth and ANC *
  • Up to 30 hours with Bluetooth only *
  • Fast charging time approx 1 hour max *



If you are curious about its actual dimensions, I just made some measurements for you:


Part 1 – Why Bluetooth 4.2 over 5.0?

Hi everyone,

We have received an overwhelming number of responses concerning the VK-X and I would like to personally thank you for your support and commitment to our project.

Today I am going to the take the time to respond to a question that has come in a number of emails.


Will the VK-X have Bluetooth 5.0?


The answer is NO for several reasons. It will, in fact, be 4.2 and it will indeed have the same efficiency of that of 5.0 Bluetooth (that is to say compatible with Bluetooth 5 devices for audio streaming), but I am going to take the time now to explain why we made this choice.

When the Bluetooth Special Interest Group (SIG) announced the creation of Bluetooth 5.0 in 2016, there was a lot of buzz generated for this seemingly major advance in wireless technology. What is interesting, however, is to see at what point certain parties including media outlets and invested companies have questionably manipulated this information for their benefit.

Here are the ‘ameliorations’ proposed by Bluetooth 5 technology that you see everywhere:

  • Range x4
  • Throughput x2


What we don’t see or what is not often stated is that, firstly, one must choose between the two ameliorations. It is one or the other in relation to the radio chosen by the system integrator (“PHY”). On the other hand, these ameliorations are exclusively for BT LE (Low energy products), which is technology dedicated to the internet of things with a very low energy consumption. The Bluetooth low energy sends small packets of information and isn’t really adapted to continuous music streaming.

Bluetooth Classic is the technology used for audio applications, via a superieur bandwidth (3 Mbps in theoretically 2.1 Mbps actually) and a profile dedicated to audio applications “A2DP” (Advanced Audio Distribution Profile)


In all fairness, to do justice to the BT 5.0, Bluetooth 5 nevertheless sets a very solid foundation for the arrival of a new standard of audio streaming, with reduced energy consumption, to achieve a theoretical bit rate of 2 Mbps, effective around 1.4 Mbps.

Nevertheless, there are several problems to be resolved, via the creation of a new profile (like the profile A2DP used for audio streaming):

  • Recomposition of segmented data packets
  • Management of asynchronous data packets



To resume,


  • Audio streaming via Bluetooth is done via the A2DP profile, managed uniquely by Bluetooth Classic
  • The bandwidth of Classic Bluetooth is higher than the bandwidth of Bluetooth LE (5.0).
  • BT LE 5.0 is a preparation for the future of audio streaming that consumes less energy and yet uses enough bandwidth for high-quality audio streaming



In my next article about this topic, I will develop more. I will explain more about Audio Formats, Codecs and Bits. Please do not hesitate to post your questions: I will be happy to answer!