the last weeks we’ve been extremely busy to prepare the shipping of the first Mellow Drives.
A look into the halls of our logistics partner show you the palets with our packaging ready to get filled with your orders.
Meanwhile Kilian and his team of engineers took the Mellow Drive for another extreme round of testing. They left the lab and went the extra mile to Fuerteventura where they found perfect conditions for some real life endurance and stress tests.
Probably the most important outcome of this trip was that we discovered a variance between the Drive Wheels and the motors. We are talking about a few hundredth of a millimeter. This small precision gap made it difficult to change wheels after a few hundred kilometers.
With the pressure to produce competing with the pressure to perform, we debated back and forth, finally deciding that this is a risk we won’t take. This means that we have to make some final adjustments. We are on it and hope to solve this issue by the end of next week.
This also means that we have to push the shipping timeline to end of March.We know this is disappointing, but you supported us loyally through all the ups and downs of this adventure that it just didn’t feel right to start compromising so close to the finish line.
And because we have prepared everything else parallel we will also be able to ship more units, approximately 150, by end of March than we would have by end of February.
To cover all the questions that probably just started popping up in your minds, we will set up an AMA (ask me anything) Live Video on Facebook with Kilian. Check out the details at the end of this update.
But the trip to Fuerte also provided plenty of good news concerning hill climb performance, heat management, recuperation, etc.
The Mellow Drive is capable to climb a constant hill grade of 5-12% at a constant speed of 20-30km/h over a distance of 3,5km. That’s a pretty long hill.
And once you reach the top you can recharge your battery on the way down in half the time your fast charger could.
For a short distance the Mellow Drive also masters up to 20% hill grade, but you should enter such a steep hill with some ground speed to make it easily to the top.
Heat management on level ground proved to be excellent. Even after riding three battery packs flat in a row at full speed the system only reached temperatures around 50°C maximum. Just for comparison, the hardware is designed to stand temperatures of up to 120°C.
Going uphill or downhill of course is a different story. In these conditions heat rises faster. That’s why we implemented what is called a derating system. This system stabilizes the Mellow Drives internal temperature by gradually adjusting the available power. It protects the Mellow Drive from overheating and keeps the system in an optimal state. But most importantly it protects you, because it prevents hard shut downs.
We were able to finetune this derating process so well that you won’t even notice when the system starts to protect itself because it is derating dynamically according to your riding behavior.
For some more nerdy details check out these diagrams:
The top graph shows the “Riding Speed” whereas the lower one shows the temperatures measured by the Mellow Drives 4 internal temperature sensors as well as the limiting of available power. The lower diagrams data was acquired in the run shown in the video.
So what do
the graphs mean? The main graph to follow is the dark blue one from the
“Temperatures & Limiting” diagrams. In our initial derating mechanism it
would jump up to 40% (limiting power output to 60%) when the threshold temperature
was reached and then back down to 0% when the system had cooled a bit. As you
can imagine from looking at this graph the rider would experience a sudden loss
of power and then a sudden increase in power over and over again. This was
quite unsatisfying to us, so we went back to the drawing board and designed a
You can see the result in the lower two diagrams.
Once the system hits 65°C the available power is gradually reduced until the system finds a thermal balance around 80°C (internal temperature). For the rider this reduction is almost unnoticeable and very smooth.
And because there’s always things that can be optimized, we will offer constant updates even after we started shipping. The software of the Drive, the Battery Pack and the Remote can be updated anytime via the App.
The iOS Version will be launched by mid of March in the App Store, the Android Version will follow shortly after in the Play Store. We will announce it as soon as they are ready to download.
The first update will be the Endless Ride Mode which we are still busy finetuning. It will show up on your Remote but still needs an update to be unlocked.
If you have any more questions, please feel free to submit them via email at firstname.lastname@example.org or directly below this post on facebook:
We will collect
them until Sunday 6:30 (CET).
From 7 - 8 pm the AMA live video with Kilian will take place on our facebook channel.
If we don’t manage to cover all your questions in that hour you can of course also contact us anytime afterwards.
Johannes & Kilian