For the past year and half we have been testing everyone’s e-kickboard scooter, e-skateboard and many other forms of Micro-EV’s.
We are noticing a few trends sparking up and that we just can’t ignore “wireless control input, sensor based control and magnetic resistive braking.” There are 2 major types of control inputs “wired and wireless.” Also, there are also two major types of Micro-EV brakes “brake line or magnetic resistive.” Lets take a look at a few examples of each type.
The “wireless” Wii nunchuck style e-skateboard controller delivers a wireless signal to a wireless receiver breakout-board which is wired to the ESC (Electronic Speed Controller.) Some of these wireless controllers operate on a bluetooth signal others on 2.4GHz bandwith. Basically, push forward on the controller’s knob and the vehicle accelerates forward, hit the brake function and motor starts to spin in reverse (re-gen or resistive braking mode.) When (not if) the wireless signal drops the ESC kills the motor’s power/ braking, which is a both a blessing and a pitfall. The first time you drop signal it’s very scary especially in urban traffic or descending down a large hill.
Shown above is the VESC Open Source ESC (geared towards DIY e-skateboards) by Benjamin Vedder and Enertion Boards. Quite honestly with the available Open Source Mac-OS X programming tools, we are very excited to get our hands on one come this spring season. This technology has been out for a number of years and the open source community is making leaps and bounds recently with slower RPM, FOC/ Sensorless settings that has us very intrigued. This ESC has inputs for many types of controls, sensors, displays etc…..
The other form of “wired” sensor based controls that has peaked our interest is the Citybug 2 electric kickscooter from Germany. Throttles are for the most part illegal in most EU countries for Light Electric Vehicles. An ingenious workaround the Citybug 2 scooter has come up with is a “Push & Pull” sensor. The rider pushes on the handlebars which has a slight give, it acts like a throttle and the motor starts to move forward. If the rider pulls back on the handlebars it actuates the resistive re-gen brake mode (albeit very slowly.) We haven’t taken the scooter apart but our guess is some sort of hardwired strain-gauge sensor is at work here in the headset/ fork tube. Similar technology to some e-bike torque sensors, so it’s only a matter of time till the responsiveness of the sensor is commute ready.
Shown above is the Citybug 2 scooter designed in Germany. We test rode this scooter twice, it’s a beautiful design and a great looking scooter. However, it’s extremely under-powered for the American market and the response time for the sensor is very slow. Fun for a leisurely ride in the park, but we can’t see commuting on this vehicle and keeping up with auto-traffic safely. We look forward to what the Citybug 3 will have to offer….
The Zboard and the One-Wheel are worth mentioning using hardwired weight, accelerometer, and gyroscopic sensor technology but the high retail cost can be test prohibitive for us.
Probably, the most successful re-gen/ resistive brake Micro-EV is the e-Twow. They are really the market leaders in the lightweight e-scooter category and one of the first to market. They have a hardwired thumb throttle on the right and a hardwired resistive e-brake thumb throttle on the left. Something the company likes to call KERS Technology – Kinetic energy recovery system.
We bought the e-Twow on a whim at a tradeshow and quite honestly we fell in love with it. Despite the mixed review from Wired magazine.
We still feel that this product is the “lightweight portable” market leader with the most well thought out tooling. Also, keep in mind this product’s design is almost 5 years old already. The designer had to make and tool many of his own original parts before any of his competition. It’s not the slickest or most beautiful I.D. but the riding function is really nice.
Upon riding the scooter, the re-gen brake is strong but not too jerky. It takes a couple of meters to come to a complete stop on flat ground. On a descend down a 12~15% hill grade the resistive mode can not be trusted as a real braking device, only to re-charge the battery which it does nicely. There is a rear scrub brake for this type of braking which also has a wired re-gen sensor in it.
After a week of riding this product you start to think to yourself, why doesn’t every Micro-EV have this re-gen only resistive brake. Then a car pulls out in front of you or a parked car almost door’s you.
You realize, nothing replaces the responsiveness and reliability of a hardwired throttle or sensor and a real brake line…..