Introduction: Electric Mountainboard DIY With 3D Printed Parts

This electric mountain board has a perfect ratio of torque and top speed with crazy acceleration!

The purpose of this page is to detail all the required parts and steps to build your own electric mountain board.

Budget for mechanical parts and electric components: $380 (USD)

Budget for the mountain board with wheels, trucks, and deck: $620 (USD)

Overall budget: $1000 (USD)

Build time: 10 hours to one weekend

Theoric speed of my current setup: 60km/h – Effective speed with my settings: 55km/h

Range of my current setup with 8S 10400mAH: 20km

This page is detailed and aims to popularize the concepts and use of each component for beginners. For advanced makers, please go directly to the parts list and wiring diagrams. Check also my Electric longboard tutorial! (cheaper and easier build to start with)

Please check the full and enhanced tutorial on my website and you can also check my other Electric Longboard build on Instructables

------ Note that I can print it for you and send a full kit including screws! ------ !!! Order a full kit here :)

Please help me develop new projects and release it on Instructable, support me on Patreon or just pay me a beer on Paypal to say Hello and/or Thank you!



Before to start, please check the following requirements:

Learn how to ride a longboard first, it’s very important to learn skateboard basics before to start this project. This will prevent you from injuring yourself by taming the engine’s propulsion in addition to attempting to manage your balance and steering.

This project requires tools and specific equipment. I personally add to use a soldering station because my batteries’ connectors were not standard and I had to use a hot glue gun, a hex key set, an electric screwdriver, my rotary tool to adapt my truck to my motor mount and to create a handle in my deck. These tools could be totally optional and I will detail one setup below that require just some tapes, screws, hex keys and sockets. I would like to recommend to buy a skateboard tool as it brings together all the socket sizes needed to set your trucks and wheels and a screwdriver.

Always wear a helmet and appropriate protections before attempting any and for the use of your e-skateboard, you can seriously injure yourself if you are not careful and properly equipped.

Step 1: Basics and Considerations

Picture of Basics and Considerations

An electric vehicle needs basically a source of energy, a motor and an electric speed controller, a transmission that will drive the wheels with the help of the motor, and a controller to send the signals to the electronic speed controller (ESC). In this particular build, we have two ESC and two motors.

Please check my tips for choosing your mountain board.
If you do not want to read everything and just want a quick recommendation, buy a Trampa HolyPro or an MBS Comp 95.

Motors

Brushless motors for RC models are commonly used for electric longboard project. My build is based on two RC Car motors.

These motors are usually categorized by their KV rating. The KV rating refers to the rpm constant of a motor – the number of revolutions per minute that the motor will turn when 1V (one Volt) is applied with no load attached to the motor. It is related to the power out from a motor, or more usefully the torque level of a motor. In summary, a low KV motor will produce higher torque, a higher KV motor will produce higher speed but less torque.

Suitable motors for electric skateboards obviously need to have high torque (between 150kv and 300kv). Most mountain board builders are using 190kv motors, but I wanted to have a perfect ratio between top speed and torque and 245kv seems to be very good for my needs: I can climb hills covered with grass like a charm, cross any rough roads and the acceleration is crazy. Top speed is amazing!

Mounting two motors on mountainboard trucks require designing custom mounts able to withstand shocks and hold firmly. I spent weeks on testing on developing mounts that are economic, extremely resistant and are modular (able to add custom light mounts, reflectors…). If you can’t make yours, I would be glad to provide the parts for a fee.

ESC

An electronic speed control or ESC is an electronic circuit with the purpose to vary an electric motor’s speed, its direction and possibly also to act as a brake. ESCs are often used on electrically powered radio controlled models, providing an electronically generated source of energy for the motor.

The first important aspect of the electronic speed controller is the voltage and current rating, which must not be exceeded. An ESC should always indicate how many volts you can pump through it and this is often expressed in how many cells you can use (the number of cells your battery has). For this project, you should look for an ESC that is able to handle 8S to 12S batteries.

You need also to look at the current rating (maximum AMPS) and make sure your motor draw will not exceed that. Most motors will say how many amps they draw (MAX AMPS) and this rating should never exceed the amp rating of the ESC. Actually, you need an ESC that can support very high amps as they usually are more resistant and will tend to behave better with lower amp draw.

Most modern ESC contains microcontroller interpreting the input signal and appropriately controlling the motor using a built-in program, or firmware. this firmware can be configured by using a programmer. I will also explain in details how to configure the ESC I use.

Batteries

Just like the motor and the ESC, the LiPo batteries used in this project are widely used for Radio Controlled Models. These are rechargeable batteries of lithium-ion technology using a polymer electrolyte instead of the more common liquid electrolyte. A LiPo battery is defined by:

  • Its cell number (also referred as “S”: a 3S battery having 3 cells) which define the voltage (see bellow)
  • Its voltage, determined by the number of cells. Tere are a few common voltage measurements worth noting:
    • Charged: the voltage of a fully-charged LiPo cell is 4.20V. A fully charged 3S pack is 12.60V. Please note that charging above this will damage the cell.
    • Nominal: this can be considered a sort of “half-charged” voltage, as it is 3.70V, in between charged and discharged. Nominal voltage is what manufacturers use when describing the voltage of their batteries. For example, a 3S battery is marked with its nominal voltage of 11.1V (3.70V*3 cells).
    • Discharged: the voltage of a discharged LiPo cell is 3.00V. But weconsider that discharging below 3.3V will definitely damage the cell.
    • Storage: When you want to store you battery for a few weeks or months, I strongly recommend to charge or discharge each cell to approximatively 3.80V which is the most stable state of a cell.
  • Its discharge capacity, exprimed in with an integer followed by “C”. The C rating of a battery tells you how many amps can be safely drawn from the battery constantly. By multiplying the C rating’s coefficient by the capacity of the battery in Ah, you can determine the sort of amperage you can draw. In the case of a 3S battery with a capacity of 5000mAh (5Ah) and a C rating of 20C, I can multiply 20*5 and get the max constant output of my battery, which is 100A. You will want that this max constant output is equal or above the max amps rating of your motor.
  • Its capacity, measured in mAh (milliamp hours). This basically tells you how long you can expect the battery to last on a charge. A 5000 mAh is equal to 5Ah (amp hours), which means that the battery can discharge at 5 amps for one hour, 2.5 amps for 2 hours, etc.

I will recommend a list of batteries for this project and the adapted chargers BUT using LiPo batteries requires special attention and misuse of these batteries (such as complete discharge, shock, hazardous storage, etc.) can lead to a start of fires and serious injuries.

I strongly recommend to read this safety guide and to check this guide to learn more about Lipo batteries.

Note that you can use for this project multiple batteries in parallel and/or in series. Plugging two batteries in series means that you will double the cells and so the voltage for the same Amps capacity, in contrary to the parallel wiring that double the amps capacity for the initial number of cells (or initial voltage).

I have multiple sets of batteries:

  • 2 x 3S 8000mAh in series (6S 8000 mAh)
  • 4 x 4S 5200 mAh, 2 packs of 2 batteries in parallel, and then the two packs in series (8S 10400 mAh)
  • 2 x 6S 5000 mAh in parrallel (6S 10000 mAh)

Connectors

The transmission is composed of a timing belt that connects a small pulley attached to the motor and a large pulley attached to one wheel.

Timing belt

A timing belt is a flexible and non-slipping mechanical drive belt with teeth molded onto its inner surface. Multiple types of timing belts are available but for this project, I use a 5mm Pitch HTD Timing Belt of 15mm wide. HTD belts have been designed to withstand loads.

Motor pulley:

The motors pulley is way smaller, with a small number of teeth (usually between 12 and 16 teeth). You have to be careful of the pulley bore diameter. For this project, I use a 15 teeth pulley 8mm bore.

Wheel pulley:

This pulley is larger (with a higher number of teeth, usually between 60 and 75) and is attached to the wheel with an adaptor to add some space between the hub and the wheel. I have designed and printed a 72 teeth pulley for this project.

Step 2: Parts

My current setup is composed of 4x 4s 5200mAh Batteries, 2x 245kv motor, 2x 160A ESC. I have designed my own motor mounts, ESC Enclosure adapted and 72T wheel pulley and it has reduced my budget significantly. This build will cost approximatively 1000 USD. FYI, I had very good results with a 6S setup, especially when I am downtown and I don’t need to go or can’t go full speed. It’s smoother for commuting with stops and pedestrians. So, I have a 8S set for when I want to cruise at higher speed and 6S set when I am commuting.

You are free to source similar parts on your own, but note that I have tested this part list and it works well. Using any other parts is your own responsibility: check the specifications of the suggested parts to be sure that it matches your locally sourced part. If you don’t want to design your own motor mounts, enclosures and pulleys, please check the kits I propose here.

Main components

Connectors

  • 2 x XT60 to XT90 adaptors (I wanted to be able to switch from one build to another, using only XT60 as all my builds are not using XT90 as well as my charger)
  • 1 XT90 Series Cable (choose Type C)
  • 10AWG Silicone Electric Wires (Red and Black) – I used 1 meter
  • XT90 Connectors (I used 3 Pairs, to create a battery lead)
  • 1 x XT90 Parallel Cable (to connect both ESC to the battery lead)
  • 1 x XT90s Anti Sparks Connector (to make a XT90 Key and prevent sparks, might be overkilling if you use MAX6 ESC as they already have a anti spark protection but I prefer to double it)
  • JST XH Extension cable (Depending on the battery cell number you choose. I used these for connecting the Lipo Checker on top of the battery box to the batteries balance cable inside the box)
  • 6 x 5.5mm Bullet Connectors (to adapt the motor’s bullet, as I received them with 4mm bullets, and the ESC’s are 5.5mm)
  • Servo Cable Splitter (to connect the Receiver to both ESC)

Batteries and chargers

  • The batteries I use are not sold anymore, I bought the 4 last pieces from Hobbyking. Some units are available on eBay but they might be fake or overpriced. I will list Batteries in another Tab in this section so you will have choices. I love the ZOP Power sold by Banggood. I have 4 of them for my other builds and they are cheap but very reliable.
  • 2 x Lipo checkers (I chose to have quality and precise lipo checker this time, and I have to admit these are amazing!!)
  • 1 x ISDT Safe Parallel Charging Board
  • 1 x Charger. You need a robust charger with at least 8Amps charging capacity
  • 1 x Power supply + 1 Power chord adapted to your country (mine is 110V only). You need a 300W min. power supply rated for 8A minimum to charge the batteries. I would recommend that the power supply is rated for at least 300W to fully use the recommended charger but you can find cheaper alternatives that are rated for less (it will just be less efficient). I have bought a new one a few weeks after (this one) as I wanted something light and easy to travel with.

3S (for 6S setup)

4S (for 8S setups)

6S

Tools and Misc.

DIY / Custom Part

Gears and Protections

Alternative Parts

Motors

Misc.

Step 3: ESC Calibration and Programming

Picture of ESC Calibration and Programming

ESC Connector Soldering

The objective is to remove the 2 T-Plug connectors that come with each ESC, shorten the wires and add a new male XT90 connector.

Please use safety glasses and proper tools as you could hurt yourself. If you have never used a soldering iron and you are not sure about getting into the conversion of the connector, ask someone who has the experience to do it.

Requirements

  • Soldering station
  • Welding wire
  • 2x XT90 male connector
  • Heat shrink tubes

Steps:

  1. Cut the black wire at about 6cm from each ESC unit T-Plug connector
  2. Cut the red wire at about 6cm from each ESC unit T-Plug connector
  3. Strip about 5mm of the end of the black wires
  4. Insert each black wires into a piece of heat shrink tube
  5. Strip about 5mm of the end of the red wires
  6. Insert each red wire into a small piece of heat shrink tube
  7. Solder each red wire to the + side of one XT90 MALE connector and then the other XT90 MALE connector
  8. Insulate the solder by heating the heat shrink tubes
  9. Solder each black wire to the – side of one XT60 MALE connector and then the other XT90 MALE connector
  10. Insulate the solder by heating the heat shrink tubes

ESC Calibration and Programming

Throttle calibration

  1. Connect the batteries to your ESC(s)
  2. To calibrate the throttle min/max, hold the set button down before you turn on the ESC and keep it down as you power it on
  3. Release it as the red light blinks. Release too soon or too late it will not get into the throttle calibration mode.
  4. Turn on your transmitter with all commands set to their neutral position
  5. Use the throttle command to reach the maximum position for acceleration and hold the position
  6. Press the calibration button, you should hear beeps
  7. Release the throttle to the middle position
  8. Use the throttle command to reach the maximum position for braking and hold the position
  9. Press the calibration button, you should hear 3 beeps
  10. Release the throttle to the middle position you should hear beeps
  11. Test the throttle to ensure that the process is done: you should be able to accelerate.
  12. Turn your transmitter off
  13. Turn the ESC(s) off

ESC programming

Link to the product page

Link to the manual

Link to the software (if you want to use a computer)

Change the settings as follows:

  1. Running Mode: Fwd/Br (you can also use Fwd/Rev/Br if you want to have reverse mode)
  2. LiPo Cells: Auto Calculation
  3. Low Voltage Cutoff: Intermediate
  4. ESC Thermal Protection: 105C
  5. Motor Thermal Protection: Disabled
  6. Motor Rotation: I have both CCW because I have tested my wiring with the motor before changing parameters in the ESC. You can either switch two cable of the motor or change the value here if you motor do not spin in the correct direction)
  7. BEC Voltage: 6V
  8. Max Brake Force: 50%
  9. Max Reverse Force: 25% (or Minimum)
  10. Start Mode (Punch): 1
  11. Drag Brake: 0%

Step 4: Build

Picture of Build
  1. Assemble the trucks to the board and remove the Dampas provided with the trucks
  2. Add the wheels to the trucks but leave the drive wheels apart
  3. Add the motor mounts to the rear truck and make any required adaptation to adjust it (sanding, filing...) and put some thread-locker to the motor mount screws.
  4. Add the motors to the motor mounts
  5. Add the small pulleys to the motor's shafts
  6. Add the large pulleys to the drive wheels
  7. Add the drive wheels to the trucks with the belt and then adjust the belt to both pulleys
  8. Tension the belt by adjusting the distance between the motor and the truck
  9. Follow the wiring diagram for the electronic components and fix everything to the deck with hot glue, duct tape, a 3D printed enclosure...

Step 5: Issues

Motor shaft

The SK3 motor shaft is perfectly circular. However, most engines of this type have a flat face which allows tightening one of the motor pulley screws which makes it possible to fix the pulley to the shaft with a better grip. During my maiden ride, the pulley of my left engine began to slide on the shaft and almost be stuck to the support of my engine … it could have blocked the pulley and severely damage the motor. I therefore file each shaft to add a flat face.

Discharge rate of my batteries

My 4S battery set was rated for 15C discharge (30C burst) and I experienced some jerky starts. I would recommend batteries with discharge rate higher than 30C.

Carrying the board

It’s very heavy compared to my electric longboard!! In order to travel, I just grab the front truck and let the rear wheels on the floor and I just pull it. I am working on a handle to make it easier.

Step 6: Upgrades

Please go to http://makertuts.com/electric-mountainboard-tutorial/ to check all updates and upgrades

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Bio: I am a curious young man, with a strong interest in DIY and an overflowing imagination. I build RC models since a few years now ... More »
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