Glossary of Terms | Electric Skateboard Terminology

Series: Connecting two batteries together to double the S rating

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You might as well also add Parallel in there as well. (2 batteries piggy backed for double running time) and ESC: electronic speed controller. Baseplate: part of truck that bolts to the Deck. well while im there… Truck: short for truckle, from the latin word trochlea meaning wheel or pulley. Deck: the wooden (or carbon fibre) part of the board that you stand on. carbon fibre… c’mon this thing writes itself.

Mah: A milliampere hour (mAh) is 1000th of an ampere hour ( Ah ). Both measures are commonly used to describe the energy charge that a battery will hold and how long a device will run before the battery needs recharging.

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KV: In the eSk8 world, KV is the number of revolutions per minute that a motor will turn when 1V (one Volt) is applied with no load attached to the motor. Generally, lower KV motors (in the range of 170KV-245KV) will produce more torque at lower speeds than high KV motors.


#B Baseplate: The part of the truck the bolts to the deck and attaches to Hanger. The Baseplate contains the pivot cup and the channel for the Kingpin

Bushings: A component of the Truck typically made of urethane that allows for the movement of the Hanger while attached to the Baseplate. Bushings directly affect the handling of the board and are often replaced to achieve a desirable affect on performance.

#C Cup Washer: A component of the Truck that goes between the Bushing and the nut and the Bushing and the Baseplate and allows for the Bushings to be compressed or decompressed for the desired performance characteristics.

#E Enclosure: A box or lid designed to protect your electronics that fastens to the board, often to the bottom of the deck. See also Components Housing.

#K Kingpin: the large bolt that runs through the truck attaching the Hanger to the Baseplate. The kingpin holds the Bushings and Cup Washers in place and keeps them aligned with the Hanger while holding the entire assembly together.

#M M4, M3, etc Metric Screw Sizes: M indicates metric, and the number immediately following it is the diameter of the screw or bolt in millimeters. Course threads are assumed unless otherwise noted, usually. For example, an M4 is a screw or bolt that has a diameter of 4mm and has course threads.

#P Pivot Cup: A urethane or plastic cup that fits into the baseplate and allows for the Hanger to pivot against the baseplate.

#U Urethane: A material for manufacturing skateboard wheels, Bushings, and slide pucks as well as tail guards, side rails, foot stops, and nose guards.


xSyP: the description of cells in a battery where x is the amount of cells in Series and y it the amount of cells in a parallel group. eg: 3S2P means 3 cells in Series and 2 parallel groups. 6 total cells combined to make 1 battery.

hmm probably e- epoxy is a term used to denote both the basic components and the cured end products of epoxy resins, as well as a colloquial name for the epoxide functional group. Epoxy resins, also known as polyepoxides are a class of reactive prepolymers and polymers which contain epoxide groups. p- Polyurethane is a polymer composed of organic units joined by carbamate links. While most polyurethanes are thermosetting polymers that do not melt when heated, thermoplastic polyurethanes are also available.

I know its a glossary but for newbies i think it would be better accompanied with pics or links to pics.



#A #B Baseplate: The part of the truck the bolts to the deck and attaches to Hanger. The Baseplate contains the pivot cup and the channel for the Kingpin

Bushings: A component of the Truck typically made of urethane that allows for the movement of the Hanger while attached to the Baseplate. Bushings directly affect the handling of the board and are often replaced to achieve a desirable affect on performance.

BLDC Brush-Less Direct Current is a common type of motor.

BRUSHLESS OUTRUNNER A common type of motor used for building DIY electric skateboards, This type of motor spins its outer shell around its windings

#C COMPONENTS HOUSING Some type of protective case or cover that fits over the electronic component beneath the deck. It may be attached using screws, glue or strong double sided tape. Plastic & Aluminium are commonly used to make the enclosure.

#D deck: the flat standing surface of a skateboard, usually laminated maple.

Drivetrain: is the group of components that delivers power from the motor to the wheels. This excludes the motor that generates the power. So basically the Drivetrain of an electric skateboard consists of four key parts.

The Motor Pulley The Wheel Pulley The Drive Belt The Motor Mounting Plate and Truck Clamping Parts, referred to as the Motor Mount

DD Dual Diagonal Mounted motors, one motor on the front truck, another on the rear truck, in diagonally opposing positions.

DR Dual Rear Mounted Motors, Both mounted side-by-side on the rear truck. DUAL DRIVE An electric skateboard with two separate motors.

#E Enclosure: A box or lid designed to protect your electronics that fastens to the board, often to the bottom of the deck. See also Components Housing.


#G grip tape: sandpaper affixed to the top of the deck with adhesive, used to increase the friction between the deck and the skater’s feet.

#H HANGER is a part of the skateboard truck that holds the axle and pivots on the truck base plate.

#I #J #K KEYWAY & KEY The keyway is a slotted section found on a shaft & in the bore of a pulley that houses a key, normally a small rectangular metal block, of the same dimension as the slot. They are used to lock the pulley & shaft together in a fixed position. This is a very reliable method for securing a pulley onto a shaft and can handle high speed & torque output without the pulley slipping.

#L LIPO lithium-ion polymer is a common battery chemistry

#M #N nose: the front of the skateboard, from the front truck bolts to the end. #O #P #Q #R #S SERIES Connecting two identical batteries together in series5 will double voltage.

STREET YOUR FACE to unintentionally face plant due to rapid acceleration or other sudden change in velocity or direction while riding an electric skateboard.

#T THANE Skateboard wheels are commonly made using urethane, thane is an abbreviation.

tail: the rear of the skateboard, from the back truck bolts to the end trucks: the front and rear axle assemblies that connect the wheels to the deck and provide the turning capabilities for the board. #U #V VESC Vedders Electronic Speed Controller (Designed by Benjamin Vedder)

#W Wh Watt Hours is a way to express total power volume inside a battery, Wh = Nominal Voltage X Amp Hours. Therefore a 10 Volt battery with 10Ah capacity is 100Wh

wheelbase: the distance between the front and back wheels, measured between the two sets of innermost truck holes. #X #Y #Z


so batteries in series… if someone refers to a ‘‘6S’’ does it mean 6 batteries connected in series?

@Driftwood 6s means 6 cells in series. One cell is around 3,7 volts.

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I would add to this to make it simpler to understand :

Cells in paralel - You’re practically making a larger battery using small 18650 individual cells, this way you iincrease capacity

Cells in series - link batteries between them to increase voltage

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Here’s some images for trucks and wheels that I found on Instructables. I find images are way more helpful than reading words-only definitions:

Edit: This is a fairly outdated wheel image. See jmasta’s reply for a much better diagram

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FOC would be nice…

FOC is a pretty complex topic, but I’ll try and explain it as simply as I can and keep the ElecEngg terms to a minimum (this is a good place for it, right?). I’ll also include some background on electric motors, so hopefully this post is a good one-stop-shop for people getting up and running with motor theory. Going to be a long one - sorry about that :stuck_out_tongue:

Basics of Motors

A motor spins because of the interaction between a permanent magnet, and a changing electromagnetic (EM) field. The changing electromagnetic field is controlled by “windings” of copper wire. Passing current through these windings creates an electromagnetic field. A motor is made in two halves - the stator (the part that is stationary), and the rotor (the part that turns).

To make the motor turn, we control the electromagnetic field on one part of the motor (in our case, the stator, but not always!) such that it’s constantly ahead of the permanent magnet on the other part of the motor (again, in our case, the rotor). The attractive force will make the two halves of the motor spin relative to each other.

Here’s a diagram that might help. Note that the stator is generating the EM field, and the rotor is a permanent magnet.

Brushed and Brushless

Now, a Brushed Motor uses a physical “brush” which electrically contacts the motor’s commutator to change the direction of the electromagnetic field as the rotor turns - keeping the electromagnetic field ahead of the permanent magnets. Here’s another diagram to help visualise this:

(Note that the rotor of a brushed motor generates the EM field rather than the stator as we saw above)

The reason we dont use brushed motors is because the brush-commutator system increases frictional losses in the motor. And, of course, there’s an extra part that can now wear out (the brushes), causing the whole motor to fail. There are other reasons too, mostly relating to the torque the motor can produce (brushed motors aren’t as good as brushless in this regard).

A BLDC (Brushless DC) motor, obviously, doesn’t have brushes. So, how do we get it to turn? Well, we move the electromagnetic field in a solid state way (with transistors - electronic switches - controlled by chips on a circuit board). In a simple sense, a BLDC motor runs on a three-phase system. There are three voltages that are put across the motor’s windings.These voltages control which of the windings have what strength of magnetic field. Effectively, each separate winding produces its own field that adds up with all the rest to become a single electromagnetic field pointing in whichever direction we chose (even in a direction not directly in line with a winding pair).

A brushless outrunner is a motor where the outside spins - rather than the inside (as with the above diagram). Here’s another diagram that should clear things up:

Outrunners are mechanically better than inrunners (where the inside turns) because the torque is applied to a larger-circumference device (for the math nerds, the moment arm is longer). Outrunners intuitively therefore lot more common. There are also some construction benefits to this design. Also notice how there are a lot of magnets involved. The same basic principle applies, but this time with more coils so we can get a smoother turning action (more on that later). The motor above has 14 poles (7 pole pairs). This is fairly typical on a BLDC outrunner.

ESC - Electronic Speed Control (and why we need them)

This three-phase control is what the ESC (electronic speed controller) is for - it generates the (ideally sinusoidal, but not always) voltage curves that drive the motor. You can’t just plug in a BLDC motor and expect it to spin - you need to be controlling the electromagnetic field somehow. Thus, use an ESC. (Quick note for newcomers: VESC is a special type of ESC that is more suited to electric skateboarding). Here’s another diagram (phase A for the voltage across winding pair A1-A2, phase B for voltage across pair B1-B2, etc.)

Notice how the infinitely smooth sinusoidal signal is turned into a “steppy” (PWM - pulse width modulation) signal before being applied to the motor. This must be done because the ESC uses transistors, which are either on or off. Not in between. That’s why we use PWM to control the motors - it effectively “turns on” the voltage for a certain percent of the time, acting like the voltage was just constantly at said certain percent. Many motors have more than 3 winding pairs, as above. This is to produce a “more round” magnetic field. That’s a terrible bit of physics, but it does make operation much smoother. Note that it’s all still three-phase (three seperable electromagnetic fields) though.

When you control the fields in this way, you produce a (relatively) smoothly rotating electromagnetic field that makes the permanent magnet part of the motor spin. Because you’re effectively switching a transistor on and off to control the sine waves here, this is where you get ERPM (electronic revs per minute) compared to actual RPM. In the BLDC outrunner above, the ERPM will be 7 times the RPM of the motor, because you’re dealing with 7 pole pairs worth of switching frequency. (If you’re using a VESC, you’ll come across ERPM and may want to read a better explanation :wink:)

FOC - Field Oriented Control

There are a few important variables we haven’t addressed when it comes to motor control. These are:

  1. Starting from a stand-still
  2. Knowing where to actually point the electromagnetic field
  3. Changing the speed without throwing everything out of balance

These are more-or-less what FOC is in charge of. Before we can do any of the above, we need to know where the rotor is. We can either use a sensored setup to measure it directly (ideal, but more expensive) or a sensorless setup that guesses the rotor position based on BEMF (back EMF).

Side note on sensorless systems

BEMF is voltage generated by the motor. See, when a magnet spins in a copper coil, it generates a current. With current, comes voltage. This is the basic operating principle of a generator. When a motor spins, it generates a current in the opposite direction to the current being used to power the electromagnetic field in the motor.

We can measure this current (the BEMF) to determine where the permanent magnets are relative to the motor’s windings. Downside of this is that you can only guess where the rotor is when it’s spinning, so you may have a hard time starting the motor smoothly.

Back to FOC, when we know where the rotor is, we want to point the electromagnetic field so that it produces the maximally efficient torque on the permanent magnets. This diagram explains it pretty well:

Once we know where the rotor is, FOC accounts for a ton of things like BEMF, voltage/current phase difference (basically “lag” in the way the motor runs) and the way we want to change (or hold) speed, and will tell the ESC how to position the electromagnetic field so we have optimal operating conditions.

Finally! With all that behind us, I can say this: The underlying operation of FOC involves a fair bit of vector math, but what it does is simple: “FOC keeps the magnetic fields of the stator and the rotor offset by the right angle to produce the most optimal torque”.

Note also that other types of control systems exist to do what FOC does, but they all achieve similar goals. FOC is simply one of the most efficient ways of doing it.

If there are any questions or need for clarification, I’m happy to help!


Skateboards haven’t used loose ball bearings like that for decades

Here’s a much better diagram:


Why is there not something descriving how 10 s 2p means that there are 10 cells 8 Connected in series 2 in parallel…

Very informative CemraJC! As a new builder I have a lot to learn and posts like this help me make more informed decisions. Over 2 years since you posted and it’s still helpful. Thanks for your contribution!