What do you need to make an electric scooter?

Powered stand-up scooter

This article is about powered stand-up scooters. For scooters with seats, see Scooter (motorcycle) . For other uses, see Scooter

An electric kick scooter

A motorized scooter is a stand-up scooter powered by either a small internal combustion engine or electric hub motor in its front and/or rear wheel. Classified as a form of micro-mobility,[1] they are generally designed with a large center deck on which the rider stands. The first motorized scooter was manufactured by Autoped in 1915.[2][3]

Recently, electric kick scooters (e-scooters) have grown in popularity with the introduction of scooter-sharing systems that use apps to allow users to rent them by the minute; such systems are commonly found in the U.S and in Queensland, Australia.

History

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1919 Autoped Scooter A child on a smaller e-scooter, 2011

"E-scooter" redirects here. For electric motorcycles or mopeds, see Electric motorcycles and scooters

Electric kick scooters have surpassed internal combustion-engined scooters in popularity since 2000.[9] They usually have two wheels between 8 and 11 inches (20–28 cm) in diameter, one or both of which are fitted with an electric motor, connected by a platform on which the rider stands, with a handlebar for support and steering. The use of an electric motor makes gears unnecessary, and may support energy recovery by regenerative braking. Range and speed vary considerably according to model. One reference shows ranges of 3 to 220 km (2 to 137 mi), and maximum speeds from 19 to 120 km/h (12 to 75 mph).[10]

In 2017, some bicycle-sharing companies such as Lime, and some scooter-only companies such as Bird, began offering dockless electric kick scooter sharing services. This segment of the micro-mobility market made large inroads in 2018, with numerous dockless e-scooters appearing in major cities worldwide,[11] sometimes in controversial and contentious unsanctioned roll-outs, such as in San Francisco.[12] Different jurisdictions have their own rules regulating electric kick scooter use on public roads and footways.[13]

Overview

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Scooters of several operators in Stockholm City scooters in Tomaszów Mazowiecki, Poland

Usage

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Motorized kick scooters are used in law enforcement, security patrolling[14][15] and leisure. New ride-sharing systems have made e-scooters easily accessible. They are popular in urban areas and are used as an alternative to bicycling or walking.[16] Ride sharing companies first started dropping these scooters off in large US cities in 2018, and the need for short distance easy access transportation in many cities has meant that they have become increasingly popular with more and more companies looking to join the market.[17]

Environment

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E-scooters, and other electric vehicles, have the potential to reduce carbon dioxide (CO2) emissions which are a cause of global warming, and other pollutants, if they are used to replace travel in vehicles with internal combustion engines. Potential environmental benefits depend upon how scooters are used: if they replace car journeys they may be beneficial, but not if they replace walked or cycled journeys. Manufacture of the batteries, in particular, requires resources, and they are often not recycled. Lime estimated that globally one in four trips on its scooters replaced a car journey.[18] A December 2021 Swiss research paper[19] found that privately owned e-scooters tended to replace car journeys, but rented e-scooters emitted more CO2 than the transport modes they replaced.[20]

Safety

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E-scooters are a potentially environmentally friendly alternative personal mode of transportation that has appeal in urban settings and for short distances. However, they are not exempt from the vulnerabilities users may encounter in road traffic injuries similar to exposures pedestrians and bicyclists have shared the roads.[21] For example, Israel has seen over 120,000 imports of e-bike and e-scooters over a two-year period, but due to poor cycling infrastructure, cyclists are often forced onto pedestrian sidewalks, and pedestrians use bike lanes and thus increase the risk of traffic collision.[22] A 2022 review of medical notes found that injury rates due to e-scooters were more like those of motorcycles than bicycles.[23][20]

As availability and demand for e-scooters increases, with more powerful versions capable of reaching up to 50 miles per hour, the number of traffic accident cases has increased. Israel witnessed a six-fold increase of e-bike and e-scooter accidents over a span of three years, and China found a four-fold increase in injury rate and a six-fold increase in mortality rates.[22] However, significant gaps remain in the knowledge about the safety measures and impact of e-scooters. A particular cause of accidents is the instability of vehicles with such small wheels when, for example, hitting a pothole.

The site of a car–scooter collision in New York City

As e-scooters become more popular in urban and high traffic settings, user safety poses a major concern alongside other health risks for drivers,[clarification needed] pedestrians, cyclists and other vulnerable groups such as the elderly and children sharing the road. A study conducted in China assessed risky behaviors of e-bike, e-scooter, and bicycle riders at crossing signalized intersections and found three different types of risky behaviors including stopping beyond the stop line, riding in motor lanes, and riding against traffic.[24]

The same study found that those riding e-scooters are more likely to engage in risky behaviors. In specific, e-scooter riders were more likely to ride in motor lanes and ride against the flow of traffic through there is high variability in the types of accidents that occur and can vary based on time of day.[24] Underreporting poses as additional gaps in knowledge, as minor crashes, for example, tend to be underreported and thus unaccounted for in overall e-scooter injury prevalence [25] and there exist gaps in research on injuries related to e-scooters.[21] Scooter-sharing systems such as Lime or Bird include safety precautions on the scooters themselves, such as: "helmet required, license required, no riding on sidewalks, no double riding, 18+ years old". Apps used to unlock and rent the scooters will also have safety reminders and ask the riders to abide by local laws while using them. However, these recommendations are not always followed, and the difference in laws between cities and states makes regulation difficult.

A consumer association in Belgium tested e-scooters, concluding that a bicycle was preferable, citing many problems with the devices, including in particular battery failure and very poor braking in wet conditions. E-scooters were regulated as toys, without the safety considerations required for vehicles.[26]

When electric kick scooters were introduced in Norway, the media reported a high increase in accidents,[27] including several deaths.[28][29]

In Britain as of late 2021 privately owned e-scooters could not be used on public roads or footways; during a trial from mid-2020 until late 2022 rental scooters could be used on roads, but not footways, by users with an appropriate driving licence. At the time private scooters were widely used, illegally, on footways and roads. There were safety concerns—scooter accidents were causing injuries more like motorcycles than pedal cycles.[30][better source needed] Privately owned scooters were banned from carriage on London public transport after a spate of battery fires.[30]

Regulation

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Electric kick scooter national speed limit in Europe since 1 October 2023

 

 25km/h

 

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Australia

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E-scooters with bicycle helmets in Canberra during 2020

In Queensland, the laws around the use of e-scooters and other personal mobility devices are made and enforced by the state government.[31][32]

While some local governments in Queensland have not allowed Lime Scooter trials, Brisbane City Council is currently undertaking a Lime Scooter trial and has invited tenders for two scooter contracts in the city.

In the ACT, the framework for personal mobility devices was amended to include e-scooters and other similar devices from 20 December 2019, permitting use on footpaths, shared paths, bicycle paths and the bicycle side of separated paths. Bicycle helmets are required to be worn.[33]

Perth became the latest City to announce an escooter trial, which launched in March 2023.

Austria

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Electric vehicles with a power up to 600 watts and a speed up to 25 km/h are considered as bicycles.[34][35]

Belgium

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Belgium's traffic rules were updated on 1 June 2019 to be in line with the European Commission guidelines formed in 2016.[36] It became legal for people over 15 years of age to ride electric motorised scooters with speed limited to 25 km/h on public roads, mirroring e-bikes. Protective gear and insurance are not required by law.[37]

Canada

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Commuting in Canada with an e-scooter has increased. As power-assisted bicycles, e-scooters must follow many of the same federal laws and regulations, such as being limited to 32 km/h and not being allowed over 500 W output.[38] Ontario has recently unveiled a series of laws aimed at ensuring safety while using electric-kick scooters or, e-scooters. The new laws require all riders to carry a valid driver’s license, and those under the age of 16 must be accompanied by an adult who also carries a valid driver’s license. Riders are now also required to wear an approved helmet when operating their e-scooter and have bright lights installed on the front and back of their vehicles.[39]

Denmark

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Since 1 January 2022, helmets are mandatory.[40]

Finland

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In Finland e-scooters have the same rules with bicycles[41] and they do not have any age restrictions.[42] However, all e-scooters that have a maximum speed over 25 km/h are classified as small motorcycles and require a motor insurance.[42]

France

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Currently France only allows e-scooters on footpaths if they have a maximum speed of 6 kilometres per hour (3.7 mph). Those travelling at up to 25 km/h are relegated to bike lanes. Legislators are considering a new law that would force users of e-scooters going faster than 25 kilometres per hour (16 mph) to have a type A1 license—the same as for small motorcycles. The legal framework is very blurry and does not define where e-scooters may or may not be driven or parked. The Deputy Mayor of Paris Christophe Najdovski is lobbying Transport Minister Élisabeth Borne for a clearer framework that would give municipalities the power to tighten the rules on how permits are issued and how authorizations are given to deploy a fleet of e-scooters to operators.[43]

French daily newspaper Le Parisien found that in 2017, e-scooters and roller skates combined caused 284 injuries and five deaths in France, a 23 percent increase on the previous year.[44] The perception of e-scooters is that they are fast, silent and therefore dangerous, causing many accidents, and the need to legislate is urgent.[43]

In an April 2023 referendum, voters in Paris chose to remove e-scooters from the city after the current vendor contracts expire.[45] The ban applies to rental scooters which have been offered by several operators since 2018, although people will still be able to use privately-owned contraptions.[46]

Germany

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Sign prohibiting the riding or carrying of micro electric vehicles

In April 2019, the "electric propulsion vehicles without seats" and mono-wheels were added to the regulatory list of vehicles allowed to circulate in the streets. However, the list has yet to be submitted to the upper house of Parliament for entry into force.

The regulation makes a distinction between vehicles restricted to 12 km/h, authorized to users aged from 12 years up and which may circulate on footpaths, and those restricted to 20 km/h, restricted to cycle paths, users over 14 years old and with compulsory motor vehicle insurance and number plate.[47] There is no driving license needed.[48] Crash accident are under-reported (74% missing) when counted as declaration to police rather than to the hospital.[40]

The same rules for operating an automobile while intoxicated also apply to electric kick scooters.[49]

Ireland

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The use of e-scooters and mono-wheels has exploded in Irish urban areas in recent years, with estimated more than 2,000 e-scooters regularly traveling the roads of Dublin.

Under existing road traffic legislation, the use of an e-scooter on public roads is not permitted. According to the Road Traffic Act 1961, all e-scooters are considered to be "mechanically propelled vehicles". Anyone using a mechanically propelled vehicle in a public place must have insurance, road tax, and a driving license. However, it is currently not possible to tax or insure e-scooters or electric skateboards.

In March 2019, e-scooter owners started reporting that the Irish police force, the Garda Síochána, had begun regularly seizing e-scooters on the grounds that the owner did not have insurance.[50] This was despite a Freedom of Information request detailing that the Garda website displayed incorrect information to the public, detailing that e-scooters requiring human power to start would not be considered mechanically propelled vehicles and, as such, would fall outside the remit requiring insurance.[51] The owner groups, such as eScoot.ie, have been publicly vocal, attracting media attention and urging e-scooter owners to sign a petition for lawmakers to legalize the public use of "electric rideables" in Ireland.[52] Under growing pressure, the Minister for Transport Shane Ross asked the Road Safety Authority to research how e-scooters are regulated in other countries, particularly other EU member states. A decision is to be taken on whether or not to amend existing legislation.[53] In August 2019 the Road Safety Authority submitted a report on the use of e-scooters to Ross. The report is broadly in favour of e-scooters, however a number of significant safety concerns were raised. The Minister have announced a two-month public consultation starting on 1 September 2019.[54] The main areas of the consultation cover what personal protective equipment should be used, what training should be provided, what safety or certification standards devices should meet, what age restrictions should apply and where the devices can be used publicly.

In February 2021 Communications Minister Eamon Ryan approved draft legislation which will "regularise" e-scooters and electric bikes as commonly accepted means of transport under proposed new vehicle category, to be known as "Powered Personal Transporters" (PPTs), which will not require road tax, insurance or driving license.[55]

Japan

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Japan is removing in July 2023 the requirement for escooter riders to have a driver's license. Scooters can be ridden on pavements where bicycles are allowed as long as they are slower than 6 kph and flash a green light.[56]

Netherlands

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The use of e-scooters remains illegal after a fatal electric cart incident in 2018.[57]

New Zealand

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E-scooters in central Christchurch, New Zealand

E-scooters in New Zealand are classed as a 'Low-powered vehicle that does not require registration', provided that the output power is under 300 watts.[58] They can therefore be ridden on footpaths, roads and separated cycleways. They cannot be ridden on paint-defined cycleways on the road. Helmets are not required, but recommended.

Norway

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In Norway, e-scooters are classed as bicycles, and can therefore be ridden on footpaths, roads and separated cycleways as well as paint-defined cycleways on the road. Maximum speed is restricted to 20 km/h. Maximum weight of the e-scooter, including the battery, must not exceed 70 kg. Maximum width must not exceed 85 cm and maximum length is 120 cm. There is no age restriction or requirement to wear a helmet.[59]

Helmets for children up to 15 years are mandatory since spring 2022.[40]

Blood Alcohol Concentration (BAC) is limited to 0.2 gram per liter as for car drivers.[40]

Poland

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Electric kicks scooter in Poland

Following a court case, a new provision of the Road Traffic Act came into force as of 21 April 2019, whereby an e-scooter falls under the definition of a moped[60] (power up to 4 kW, max speed 45 km/h). Therefore, such vehicles are not allowed to ride on the footpaths as well as bicycle lanes. However, due to the lack of homologation, it is not possible to register an e-scooter as a road vehicle, which makes it illegal for the use on the road. The legislators are now working on changes to the law to introduce the definition of the Personal Transport Device, which would allow e-scooters to be used on footpaths and bicycle lanes.[61]

From May 20, 2021, the regulations on the traffic of e-scooters are in force.[62] An e-scooter is an electric powered vehicle, two-axle, with a steering wheel, without a seat and without pedals, designed to be driven only by the rider on that vehicle.

To drive an e-scooter on the road by people aged 10 to 18, it is required to have the same qualifications as for cycling, i.e. a bicycle card or driving license of categories AM, A1, B1 or T. For people over 18 years, such a document is not required.[63]

Singapore

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E-scooters in Singapore are categorized as Personal Mobility Devices (PMD), and as such, are subjected to the Land Transport Authority's regulations. All e-scooter owners are required to register their devices with the Land Transport Authority and affix the registration number on their scooter. E-scooters that are not registered by 1 July 2019 will have their devices seized by the authorities and the offender would be liable for punishment.

E-scooters sold in Singapore have to comply with a strict set of regulations; maximum speed of 25 kilometres per hour (16 mph), must not exceed 70 cm in width & must not weigh more than 20 kg. Retailers are allowed to sell non-compliant e-scooters however they have to indicate clearly that they can only be used on private property or for use overseas.

Unlike electric bicycles, e-scooters can only be ridden on footpaths and cycling paths. They are not allowed to be ridden on public roads.

Spain

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E-scooters' recurring role in traffic accidents has led to a regulatory pushback in Spain. There have been reported 273 accidents, three of which were fatal in 2018. Spanish legislators are working on a regulation banning e-scooters from footpaths and limiting their speed to 25 kilometres per hour (16 mph).[43]

The first ever person hit by e-scooter died in Spain in August 2019. A 92-year-old woman fell and struck her head to the pavement when an e-scooter hit her, travelling at less than 10 kilometres per hour (6.2 mph).[64]

Spain is introducing technical standards and mandatory helmets.

Turkey

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E-scooters can be used on cycle paths, and on urban roads without cycle paths where the speed limit is below 50 kph.[65]

United Kingdom

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Privately owned e-scooters are deemed to be Personal Light Electric Vehicles, subject to legal requirements regarding MOT testing, tax, and licensing. In practice they cannot be made to meet the requirements for road use, and they also may not be used on footways.[66] In some trial areas from mid-2020 to November 2022,[30] rental e-scooters may be ridden on roads and cycle lanes but not footways; riders must be 16 or over and have a driving licence. Using a phone, driving under the influence of alcohol, and other risks, are not allowed, as for other motor vehicles.[66][67] Action is not usually taken against users of private scooters on roads and footways, but in December 2021 West Midlands Police announced that they had seized and destroyed 140 e-scooters.[68] In July 2023, the police and crime commissioner for Kent called on police to seize and crush all e-scooters being ridden on public land.[69]

In 2022 a woman riding a rental scooter erratically while over the legal limit for alcohol pleaded guilty to drink-driving. She had not known that it was an offence, but was fined, and banned from driving for 18 months.[70]

Deaths

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The first UK fatality involving an e-scooter occurred on 12 July 2019 when 35-year-old Emily Hartridge was killed in Battersea, London in a collision on a roundabout with a truck. London's cycling commissioner said that "new regulations must be put forward quickly" as e-scooters are "currently not safe—with no restrictions on speeds, no mandatory brakes and lights, and no rules on who can ride them and where".[71]

The first death of a pedestrian hit by an e-scooter occurred on 8 June 2022, when the 71-year old victim died in hospital after being impacted by a 14-year old scooter-riding male on 2 June.[72][73]

Different motorized scooters available in Long Beach, California in March 2023, including those from Bird, Lime and Veo

United States

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Rules in the United States vary by state. Motorized scooters are often not street legal, as they cannot be tagged, titled, insured, and do not meet federal requirements for lights or mirrors. Particular localities may have further ordinances that limit the use of motorized scooters. The top speed of the average motorized scooter is around 20 miles per hour (32 km/h). Due to their small wheels, motorized scooters are not typically safe for street use as even the smallest bumps can cause an accident.

California, for example, requires that a person riding a motorized scooter on a street be 16 years of age or older, have a valid driver's license, be wearing a bicycle helmet, have no passengers, and otherwise follow the same rules of the road the same as cars do. The motorized scooter must have brakes, may not have handlebars raised above the operator's shoulders, and if ridden at night must have a headlight, a taillight, and side reflectors. A motorized scooter may not be operated on sidewalks or on streets if the posted speed limit is over 25 miles per hour (40 km/h) unless in a Class II bicycle lane.[74]

Michigan laws treat motorized scooters similarly to bicycles. They are typically allowed on sidewalks, bike lanes, and roads.[75]

In Washington, D.C., motorized scooters are classified as Personal Mobility Devices, and are therefore not considered motor vehicles. This means there is no inspection, license, insurance, or registration required. Additionally, this means that motorized scooters are allowed on the sidewalks, and helmets are not required.[76]

In Georgia, motorized scooters are considered Electric Personal Assistive Mobility Devices, meaning they can be used on sidewalks and highways where the speed limit is at most 35 miles per hour (56 km/h), or in the bike lane. The law also specifies that users of Electric Personal Assistive Mobility Devices, including motorized scooter riders, "have the same rights and duties as prescribed for pedestrians".[77]

Scooter sharing companies have rules for operation printed on both the scooter and in the app, which includes instructions to not ride on the sidewalk. Given that the laws regarding motorized scooters vary from state to state, the scooter sharing instructions can differ from the local law.[78]

Mechanics

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Wheels and tires

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Stand-up scooters may have solid tires, pneumatic tires with tubes, or tubeless pneumatic tires. There is variety within each kind; solids generally have a honeycomb structure of some sort, often surrounding a hard-plastic insert. Sizes vary between 8 inches (200 mm) and 11 inches (280 mm) usually, and scooters with larger are available, for both road and off-road use. There are some with unusually wide tires especially for off-road use. Most of them use a steel or aluminum split rim.

Drive and transmissions

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The simplest drive mechanism of stand-up scooters is the electric direct drive, where the motor directly drives the rear wheel. Some electric scooters have two motors, one for each wheel. Brushless motors can be extremely efficient this way, especially when regenerative braking is implemented. A large proportion of newer so-called "e-scooters" are designed this way.

When electric direct drive is not the rule, the simplest is the spindle drive, which puts an extension of the engine's output shaft, the spindle, in direct contact with the scooter's rear tire. To work correctly, the tire must have a clean, dry surface with which the spindle can effectively interact. Scooters with this type of direct transmission can be pull-started with the rear wheel off the ground, or "bump"-started by forcefully pushing them with the rear tire in contact with the ground.

T3 Patroller electric stand-up tricycle

Simple chain reduction drives are also used to transfer energy to the rear wheel, generally incorporating a type of centrifugal clutch to allow the engine to idle independently.

Belt reduction drives use the combination of wide flat "cog" belts and pulleys to transfer power to the rear wheel. Like chain drives, belt drives include a centrifugal clutch, but are more susceptible to breakage in off-road conditions.

Suspension

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The suspension systems of stand-up scooters range from nothing at all, to simplistic spring based fork systems, to the complicated, dampened cam-link and C.I.D.L.I (Cantilevered Independent Dynamic Linkless Indespension) suspension mechanisms or a hybrid combination of wooden deck, coil spring, and dampers.

Brakes

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Brake systems of kick scooters include disc brakes; magnetic brakes; and less efficient hydraulic brakes. Brakes can be placed on the front and/or back wheel(s). Many newer e-scooter models also have Kinetic Energy Regeneration System (KERS), which also acts as an electronic ABS system (E-ABS) on some models.

Gallery

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• Man on a motorised scooter in the 1920s

• 1922 Austro Motorette 82 cc two stroke

• Example of a Go-Ped.

• An Evercross H5 e-scooter being ridden

Companies

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• AER
• Apollo
• Askoll
• Beam
• Bird
• Boosted
• Currus
• EcoReco
• EMOVE
• Evercross
• EVOLV
• E-TWOW
• Fiat
• Fiido
• Fluid Freeride
• Glion
• Globber
• GOTRAX
• Helbiz
• Hiboy
• Hopp
• Jetson
• Inmotion
• Inokim
• Joyor
• Kaabo
• Levy
• Lime
• Mearth
• Mercane
• Mii2
• Minimotors
• Macwheel
• Mongoose
• Nabi Boards
• NAMI
• Nanrobot
• Neuron
• Niu
• Qiewa
• Razor
• RION
• Segway
• Skip Scooters
• Spin
• Splach
• Swagtron
• TAUR
• TurboAnt
• Turbowheel
• Uber
• Unagi
• Uscooters
• Varla
• Vsett
• WEPED
• Work's Electric
• Yume
• Xiaomi
• Zero

See also

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References

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By Matthew Daniel    View In Digital Edition  

With the influx of electric skateboards and scooters that have taken over seemingly every city, I started thinking it might be something to purchase for myself. Currently, it’s very affordable to purchase a scooter such as the Xiaomi Mi version for around $400, as well as many startups with some awesome designs. Instead, I decided that I would try to build my own from scratch. Not really to save money, but to gain the experience of building something of my own.

FIGURE 1. Completed scooter.

This project started early summer in 2019 when I got the idea and continued for six months when I finished up all the electronics and code. Although this was a very time-consuming project, I loved every second of the process and enjoy showing people this project. All I need now is a helmet!

The primary purpose of this article is to show my design and manufacturing process, so that you can learn from what I built. I’ve endeavored to provide as much information about my design as concisely as possible.

The Physical Design

Building an electric scooter starts with two key components: the scooter frame and motor. There are two main types of motor drives for DIY scooters: belt/gear driven, or direct drive such as a hub motor. I opted for a brushless hub motor that was designed to be used on a standard hoverboard. The main reason I chose this motor is because of its unmatched power-to-cost ratio. As hoverboards were mass produced, the cost for the motor was orders of magnitude less than I could find anywhere.

Additionally, it was relatively simple to design a mount that could hold the motor to the turning axel. I wanted the motor to be in the front to keep the hand-controlled rear disc brake working. This handbrake is extremely important for an electric scooter in an area with major hills and dangerous traffic.

The largest mechanical challenge to overcome was the design of the wheel housing. Since I opted for using a hub motor, the motor mount had to support the weight of the user in addition to the torque of the motor accelerating and turning. At purchase, the scooter had a weak wheel assembly that would not be easily modified to support the motorized wheel. Figure 2 shows the wheel assembly being cut from the hex extrusion.

FIGURE 2. OEM wheel assembly cut with band saw.

Next, I used a large scrap piece of aluminum and designed a frame that holds the motor. It’s clamped with four machine bolts and a small stock piece with through holes. I used Autodesk Inventor to create the part (which is included in the downloads).

This design consists of two pieces: the main L-shaped piece which connects the handlebar actuation to the motor, and the other clamps the motor to the base with four 10-32 bolts. I was able to use CAM in Fusion 360 and a CNC machine to make the main part, with additional manual milling and tapping to finish up.

Finally, I used a manual mill to cut the base clamp and added through holes for the bolts. Figures 3-6 show the CAD model of the wheel assembly in addition to the assembly process of mounting the wheel. On the base of the scooter are two rails that support the weight of the rider, which I utilized to also hold the two LiPo batteries securely. Since LiPo batteries are highly unstable and susceptible to both water damage and puncturing, I added a metal cover to protect the batteries from each of these factors.

FIGURE 3. CAD of CNC wheel assembly.

FIGURE 4. Completed CNC wheel assembly with attached hex.

FIGURE 5. Close-up of motor mounting.

FIGURE 6. Final front wheel assembly.

To do this, I cut a piece of 1/16 inch aluminum and bent these pieces to length using a metal bender and acetylene torch to reduce the stress on the metal while bending. With normal use, the bottom is likely to be scuffed (refer to Figure 7), but the metal cover takes all the damage with no issues so far.

FIGURE 7. Close-up of the metal frame protecting the batteries.

I used 3D printing extensively in both the prototype stage as well as in the final product. The most obvious piece is the electrical box which is how the user can charge the LiPo batteries easily. This box has the main power switch, voltage divider for the Arduino to read battery voltage (as max analog in is 5V and the controller runs off 12V LiPo), and the LiPo charging connectors.

To charge this scooter, the user takes the front panel off (held down by M3 screws), detaches the XT-60 connectors from the main power, and simply plugs them into the LiPo charger. Additionally, the LCD screen housing, Arduino Nano case, folding mechanism, and waterproofing pieces are all designed and 3D printed for this scooter. All the CAD files are provided in the downloads for use in your own scooter.

Figure 8 highlights the electrical box and controller connected to the scooter frame. To attach the controller, I drilled and tapped two holes into the frame and bolted the controller on with two 10-32 bolts. The elctrical box was connected using a single bolt and a zip tie.

FIGURE 8. CAD of the scooter frame with the controller and electrical box.

This method of attaching works very well, with both boxes secured soundly. I didn’t want to reduce the strength of the scooter too much which is why I opted for as few holes into the scooter as possible.

Later in the build, I noticed that riding the scooter could be very awkward since both of my feet couldn’t fit comfortably on the small platform. This is likely because the engineers designed the scooter for the user to have one foot on the frame and one to push the scooter forward. To remedy this, I knew I had two options: add a metal plate to the top, or cut off the main frame and weld on a new one.

Sadly, I didn’t have access to a welding machine and thus had to use the first option. I was able to find a quarter inch aluminum plate that was large enough to cover the platform. I utilized a bandsaw and grinder to cut the plate to length in addition to adding a slot for the folding mechanism as seen in Figure 9.

FIGURE 9. Scooter with added standing platform.

The final major modification of this scooter was the handlebars. The handlebars that came with the scooter were so close together that it was very unstable and difficult to steer — especially at a high speed. To remedy this, I purchased an aluminum stock at one inch diameter and used a lathe to reduce the diameter until it fit into the frame.

Finally, I drilled and tapped two holes for 10-32 machine screws to hold the new bar onto the original frame. With the longer handlebars, the scooter was much more comfortable to ride and felt more stable around turns.

One key theme I had throughout all my designed components was to keep the whole system waterproof. Although it would not be wise to ride this in heavy rain, all the main electronics should be watertight. The primary concern for water is the batteries which are below the scooter.

To enclose the batteries as mentioned earlier, I bent an aluminum sheet to protect the undercarriage but also 3D printed pieces with slots for cable gland joints wire protectors to allow the wires to pass through. There are three different slots for the cabling to pass through as shown in Figure 10: main power; LiPo battery management; and battery temperature sensors. These slots were fitted with nylon cable gland joints that are watertight and very simple to use.

FIGURE 10. Photo of completed undercarriage of scooter.

Finally, I used Dynaflex 230 to completely waterproof the batteries which can be seen around the edges in Figure 10. These wires then pass to the main electrical box which uses the same cable gland joints as in the electrical box and are sealed using heat shrink tubing. Finally, each wired connection has more silicon at each joint to ensure there are no leaks.

Electrical Components

Once I picked the hoverboard wheel as my motor of choice, I decided on the controller in Figure 11 because it worked with my brushless motor and was very inexpensive. The batteries were a little more difficult to pick out.

FIGURE 11. Close-up of controller mounted to the scooter.

Since almost all scooters and bikes use Li-ion battery packs, I thought they would be the best option for me. The reason they are so widely used is due to their excellent storage capacity, charging characteristics, and they can be designed to fit almost any form factor.

Although I did do significant research into the design of a pack for my scooter, I realized I didn’t have the funds to purchase a spot welder which is used in the building of these packs. In the future, I would be interested in making another scooter or similar project where I use 18650 batteries instead of standard LiPo batteries used in this build.

To find the allowable dimensions for my batteries, I took a bunch of measurements with calipers and made a very rudimentary model using Autodesk Inventor as seen in Figure 12. With these dimensions in hand, I was able to choose the batteries to fit under the main frame of the scooter.

FIGURE 12. Simple CAD of scooter with battery (in orange).

I had 43 mm to work with for the width of the batteries, with slightly more room to allow the batteries to fit under without hitting the ground. The batteries selected were 6S and had 4,000 mAh battery life, which is a little lower than I had hoped for.

Overall, the main electrical circuitry for this scooter was quite simple to design. As shown in Figure 13, I have the two LiPo batteries connected in series which power the controller and motor. The controller reads the thumb throttle potentiometer mounted on the handlebar to set the speed of the motor. Additionally, I added a cruise control button also mounted to the handlebar next to the break. The motor is controlled with three-phase power with three Hall sensors which all output to the controller.

FIGURE 13. Scooter power driver circuit diagram.

Now that I had the main design of the scooter, it seemed extremely easy to wire up and ride. That, sadly, was not the case. Wiring up the batteries and temperature sensors was surprisingly difficult to fit them into my allotted space.

At this point in the build process, I had finalized the design of the undercarriage and the electrical box which was mounted as you can see in the final design back in Figure 1. I began by placing my temperature sensors with excess cabling through the gland joints in the base, in addition to the LiPo charging cables (26 cables in total).

Finally, I took my two XT-60 connectors and ran the cabling up to the control box. This wiring procedure can be seen in Figure 14 which shows the initial cable routing into the battery section.

FIGURE 14. Wiring the batteries into the frame base.

I then placed the LiPo batteries into the frame which fit in snugly, and began connecting the different plugs. After having significant trouble fitting the batteries and connectors into the allotted room, I realized I had to change something to get everything to fit without putting significant pressure on the cables.

I noticed that the XT-60 connectors took up a large amount of space, so I decided to remove them and have straight soldered connections. I wouldn’t recommend removing the connectors, but it was easier to remove them than it would have been to redesign the housing.

I removed each of the connectors one cable at a time, being extremely careful not to have anything short. I used extensive heat shrink tubing and electrical tape to ensure they were well insulated. As seen in Figure 15, all the wiring on the base was done and taped in place for the heat shrink tubing.

FIGURE 15. Final battery pack before shrink wrap.

I then placed the taped-up system into the heat shrink tube and slowly shrunk the whole system down until it looked like Figure 16. After this, I placed the metal sheet on for a final time and tightened down all of the bolts with Loctite to make them permanent.

FIGURE 16. Heat shrink battery packs.

As discussed briefly earlier, I designed an electrical box which sits next to the motor controller. The schematic for this simple box is shown in Figure 17.

FIGURE 17. Electrical box schematic.

To charge each of the batteries, I simply remove the male connectors from the control box and plug them into a balancing charger along with their respective balancing cables. As mentioned earlier, I would have liked to use a Li-ion battery pack which would have made the charging process much simpler and seamless. As I only had a single charger, I had to charge each battery separately.

When using the scooter, I plug in the battery’s connectors into the female connectors which put the batteries in series. In my first design, I had a standard rocker switch which was rated for 10A at 125V AC which was significantly lower than my power usage (around 250W vs. the 125W rating). These switches are really only meant to switch AC current which is much easier to do.

Sadly, within a few days of use, the switch had completely burnt out. After much research, I found any DC switch would be much too large to fit inside or near the control box. Instead, I opted for a makeshift switch with a shorted female XT-60 connector which was used to short or open the circuit. Although it’s certainly not the cleanest switch option, it’s very functional and has presented no issues so far.

From there, I wired up the controller to the electrical box and motor leaving plenty of slack for the wheel to turn. At this point, the scooter movement was complete. It was now time to design the LCD screen and accompanying sensors. The functionality I was looking for from my LCD screen was to show the battery voltage, approximate percent of battery life remaining, speed, and miles driven. The most difficult of these was getting the speed measurement working well.

To do this, I thought of piggybacking on the Hall sensors the controller uses, but I was worried that might interfere with the main control. Instead, I decided to use a Hall-effect sensor reading when a neodymium magnet connected to the wheel passed by the sensor. One issue with this design is how close the open electronics were to the wheel which would splash up water.

I designed a simple mold in which I placed the electronics and an epoxy called Dragon Skin 20 as seen in Figure 18.

FIGURE 18. Waterproofed Hall-effect sensor.

I left the epoxy off the module in blue which allows me to tune the sensitivity of the sensor. Figure 19 shows the screen housing built to hold the 20x4 character LCD screen and connect to the handlebars via screws.

FIGURE 19. CAD model of LCD screen housing.

Additionally, I built a simple box to hold the Arduino Nano and associated wiring (Figure 20). Both the housing box and screen housing utilized M3 standard hardware, including heat inserts which are melted into the parts using a soldering iron.

FIGURE 20. CAD of small electrical box for Arduino Nano.

Finally, I soldered all the headers onto the Nano and placed the microcontroller on a small protoboard. I then added female headers around the Arduino with six power and six ground connections on the side. Figure 21 shows a prototype box being wired up to test.

FIGURE 21. Prototype of the Arduino Nano box.

I used crimped connections to attach each device to the protoboard, just in case there are any wiring issues in the future. To measure the battery voltage, I added a voltage divider to the electrical box with 47K Ω and 4.7K Ω resistors in series with the Arduino connected to the 4.7K Ω resistor. The purpose of the divider is due to an Arduino running off 5V and thus being able to measure a maximum of 5V. The circuit divides the voltage of the battery by almost exactly 10, making it readable to the Arduino. The Nano schematic is shown in Figure 22.

FIGURE 22. Overall Arduino, sensors, and LCD screen schematic.

Programming

The code for the Arduino is included in the downloads. I’ll go ahead and explain the methods I used in programming this system. The hardest part of this program was getting the Hall sensor odometer and speedometer working correctly with a limited clock speed. To read the Hall sensor, I connected the output to the second digital pin which is capable of running hardware interrupts.

At every rising edge of the Hall sensor signal, the interrupt is triggered and runs a simple function seen in Figure 23.

FIGURE 23. Hardware interrupt incrementing function.

This function increments the counter which is stored on electrically erasable programmable read-only memory (EEPROM). EEPROM is a non-volatile memory which means it’s stable when the device is not powered. Accessing this memory is not as simple as defining a variable to memory; you need to send a byte of data to a specific memory address. Sadly, as the Arduino runs off an eight-bit architecture, the system would not be able to store the odometer reading in a single memory address. To fix this issue, I built some basic helper functions that write and read a “long” variable to four eight-bit memory addresses as shown in Figure 24.

FIGURE 24. Helper function to write to EEPROM.

To read the value from memory, I used a bit shift operator after reading the four bytes from memory as seen in Figure 25.

FIGURE 25. Method to bitwise convert 4x eight-bit int into a “long” variable.

The speedometer part of this program is run off TimerOne, which is a 16-bit timer running at a frequency of 16 MHz. I set the period of the timer to trigger an event every quarter second to read the odometer, compare it to the previous reading, and then calculate the speed.

The program calculates the speed by converting the change in rotations to distance. I made an array of four of the most recent speeds and output an average to smooth out the data for the LCD screen.

The temperature sensors were very easy to set up using the datasheet and a basic analogread as shown in Figure 26.

FIGURE 26. Reading of battery temperatures.

Additionally, I read the battery voltage with a very similar method, but I multiply by 10 due to the voltage divider circuit. Refer to Figure 27.

FIGURE 27. LiPo voltage reading.

The final setup was putting it all together in one program and integrating it with the LCD.

Using this LCD screen is extremely easy with the included libraries. I had to do a few tests on the LCD to ensure the placement of the mileage, speed, temperature, and voltage would not overlap and look nice as shown in Figure 28.

FIGURE 28. Working LCD screen.

Conclusion

Overall, this project was very educational. It was exciting to design the entire unit, from mechanical components to the hardware and software used. The final product has a surprising amount of power; it’s able to move me with a backpack up any hill that Ithaca, NY has to offer. I was pleased and impressed by the power the hub motor output.

Additionally, the LCD screen is very responsive and accurate with the speed and odometer measurements. Although I haven’t been able to test the range on a flat road, I estimate it’s around 6-8 miles on a single charge based on previous rides. This is lower than many scooters on the market, but I was working with very limited space under the scooter and LiPo batteries.

I would recommend building something like this to anyone who can commit the time. I logged most of the time I spent working on this, and the total was around 100 hours!

In a perfect world, I would have welded a new frame to the existing scooter. This would have given me additional room to stand comfortably and fit all of the electronics in a larger space.

In the future, I’d like to experiment a bit with building a Li-ion pack to power the scooter. I loved working on this project and learned so much. I hope I inspired some of you to build your own!  NV

Parts List

I purchased the parts from a variety of places.

Amazon:

• Scooter
• Cable Glands

Generic Parts from a Chinese Warehouse:

• Hall Sensor
• Arduino Nano
• 12 gauge Wiring

eBay:

• Potentiometer Thumb Throttle
• Eight inch Brushless Hub Motor for Hoverboard

From the Community Maker Space at Cornell:

• All Other Parts
• Temperature Sensor
• Wiring
• Soldering
• 3D Printing Supplies

Downloads

download

202002-Daniel.zip

What’s in the zip?
Code and CAD Files