Lucas
As an inhabitant of a big European city and a maker preoccupied with some environment-friendly thoughts, finding a convenient way of transportation turns out to be a heck of a conundrum.
Cars (electric or not) are doomed to decline as a commuting solution. Using a 80kW, 1.5 tons metal box to travel at an astonishing average speed of 20 km/h sounds like a environmental, energetical and economical non-sense !
Don't get me wrong, a car is useful for some purpose (weekly/monthly groceries, holidays... ) but I can't see how we could reasonably hold on the current car culture in a world which is about to reach 8 billion inhabitants. Actually, did you know that the average commuting distance in Europe is less than 20 km for 80 % of all trips and less than 10 km for 60% of those?
Agily switching between trains, subways, buses, bikes and car-pooling should be the solution for a lot of us to overcome those 15 km. Even more : flexible and micro-mobilty can become a suitable, favorable and much more enjoyale solution than the fraught daily car commute.
Anyway, I apologize for those political/ecological consideration and didn't forget that urban-mobility has to remain fun, safe and efficient. So, in a frantic quest to find an ultimate solution to accelerate my (walking) trips between the house and the bus and then the subway to work, I've been exploring the best options between e-bike, e-scooter, e-roller blades and skates.
- Electric roller-blades are probably the sexiest and lightest solution but they definitely represent a huge threat for your ankles (well at least I couldn't think of a solution to correctly secure your feet and calves which would adapt on any kind of shoes and outfit).
- E-bike are fast ; but hard to secure when parked and difficult to fit in a car or a public transportation.
- E-scooters are a better trade in terms of size and are furiously stable/easy to drive but still end up quite heavy/bulky when you have to hold of them in the urban maze that constitute the stairs, elevators and various obstacles of a transportation hub.
What does that leave us ? Well, electric skateboard and longboard are not a new thing ; and they couldn't boast being more than a compromise between the scooter and the roller blade (in terms of bulk/security ratio). One would also argue that you don't feel as safe on a skateboard than on a bike but you'll have to admit that overall stability/comfort/weight/bulk compromise is unrivalled.
Provided that you're endowed with a descent equilibrium, that we can find a reasonably stable board and wear a helmet; a compact 8kg contraption that could propel you at 20 km/h for a 15km range appears to me as the most reasonable concession. Throw in that you can also fold it to fit it in a backpack and you got a convincing solution.
Sooo, after those considerations ... shall begin the exiting journey of designing that thingamajig !
Let's sum up the bill of specifications:
- 80Kg payload
- 20 km/h top speed (let's say 18km/h nominal speed; which is 3 times the walking speed and the highest reasonable speed to safely alternate between roads, cycling lanes and pavements)
- 15km top range (to ensure more numerous cycles of your battery, I would bank-on 10km bi-daily and yet be able to do more on seldom occasions)
- has to fit in a backpack for less than 8 kg
That leave us to choose the following components:
- a foldable deck
- ~210Wh battery (I know we could theoretically expect more range from such a battery, but the goal is once again to extend the battery to 2 years or more of lifetime and be able to tackle some slopes on the way). I designed a homemade battery that would fit in the constrained foldable case and use high-quality cells: 18650 Sony VCT6 3Ah cells.
- 500W worth of motor which I decided to be 2 x 250 W, 36V, 83mm hub motors for compacity and design sleekness.
- bldc motor drivers:...
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Eric Hertz