LIKE ELECTRIC BOARDS?
Mountainboarding as a sport started in the early 90’s in the UK. It is like snowboarding but with wheels and no snow. If you are missing snowboarding because it’s off-season, but wish for the same feeling, this is the replacement thrill. Going electric means you don’t need any hills or slopes and you can ride it on any flat surface. It means you can accelerate when carving, a totally new sensation, never possible before.
What makes an electric mountainboard run? A motor, a speed controller and a remote to accelerate and brake. And of course, the power of lithium batteries.
Here is how to build it with on-the-shelf RC hobby components. First, this is not a toy, it is quite serious - it will have around 6 horse power, very good torque and speed up to 42km/h (26mi/h). The range is around one hour or 15-20km / 10-12mi depending on your weight and riding style.
The parts you need:
The Mountainboard: you have two best choices here - Trampa or MBS - both top brands, first made in UK, second from US. I chose the Trampa Holypro on Vertigo truck with Superstar Wheel & Ratchet Binding.
The motor mounting system is custom made in Germany by the company E-toxx.com
Next are the electronics - motors and speed controllers. Everything you need you can find on hobbyking.com. For motors I chose Turnigy Aerodrive SK3 - 6374. It has 2250 watts which means 6.04hp with twin motors attached on the back wheels.
The speed controller (ESC) works by adjusting the motor voltage using a remote. For this use case, to ride an all-road board with high torque you need a speed controller to support at least 150amps and 30+ volts otherwise you will not have enough power and speed. There are two choices - Hobbywing Max6 with 8s and 160A and Roxxy 9120 with 12s and 150A.
The ’s’ rating means how many battery cells you can put in series. The nominal voltage of a cell is 3.7v which means 29.6v or 44.4v total voltage. More voltage means more speed. Max6 goes up to 30km/h and Roxxy up to 42km/h.
Now, here comes the power. There are two kinds of lithium batteries that are commonly used. Lithium polymer (lipo) and lithium ion (li-ion). Lipo are used mainly for hobby rc cars/planes and comes in different voltage configurations and power. The only issue is that if not handled correctly can easily explode. And you don’t want to have that under your crotch.
The best option is lithium ion 18650 cells. The one you find in Tesla cars. Samsung 25R (2500mAg) and LG HG2 (3000mAh) are the default options.
So what do these specs really means?
Translate: more voltage = more speed, more amps = more riding time.
The discharge current (20A/cell) counts for torque. I can put up to 8 cells in parallel to add 160A constant discharge (that’s why the ESC needs to support high discharge rate, otherwise it will easily burn)
So, how many cells do I need?
8s = 8 * 3.7 = 29.6v 12s = 12 * 3.7 = 44.4v
When you wire the batteries in parallel you increase the power: 8p = 8 * 2500mAh = 20000mAh (20Ah)
8s8p = 64 li-ion cells
Now the that everything is built, it’s time for a ride. But before that remember one more thing.
ALWAYS wear body protections! Only a helmet is not enough. You will need full body armour, back protection, crash pants, knee, elbow and wrists pads - the whole shabang. Otherwise you can seriously hurt yourself.
My first test run in Hampstead Heath
If you are serious about building it and want more info, www.electric-skateboard.builders is the perfect place to start.