Traffic signsUnited States
Traffic rules
United States
201. Bicycle helmet
Abicycle helmet is protective headgear designed to reduce the risk and severity of head injuries if a cyclist falls or is involved in a collision. It normally consists of an impact-absorbing liner, an outer shell and a retention strap that keeps the helmet securely on the head.
A bicycle helmet should fit correctly, sit level on the head and be securely fastened. A damaged helmet should be replaced because its protective performance may have been reduced even when the damage is not immediately visible.
Wikimedia.org • Ildar Sagdejev • CC BY-SA
Is wearing a bicycle helmet compulsory everywhere?
No. Helmet requirements vary between countries and may also depend on the cyclist's age or the type of bicycle being used. Riders should check the rules that apply where they are cycling.
🔗 gov.uk • Great Britain Highway Code, Rule 59, cycle equipment; national guidance example
🔗 chp.ca.gov • California Highway Patrol, motorcycle safety and helmets; California example
🔗 nsw.gov.au • NSW Government, bicycle safety equipment; NSW helmet rule
🔗 service-public.gouv.fr • French Service Public, mandatory bicycle equipment; child helmet example
202. Hands-free
Hands-free refers to using a telephone or communication system without holding the device in the hand. Hands-free operation can use the vehicle's built-in system, a headset, earphones, voice control or a phone secured in an appropriate holder.
Hands-free operation reduces the need to physically handle a device, but a conversation or interaction can still distract the driver. Drivers should therefore minimise device use and keep their attention on the road.
Wikimedia.org • Benoît Prieur • CC0
What does hands-free mean while driving?
Hands-free means operating a communication function without holding the device. It can use an integrated vehicle system or another locally permitted method. A headset, earphones or a mounted phone are not automatically legal in every jurisdiction, and hands-free use can still distract.
🔗 gov.uk • Great Britain Highway Code, Rules 159–169, observation; national guidance example
Does hands-free use allow you to hold the phone?
No. Holding a telephone while calling is not hands-free use. Whether handheld or mounted-device use is legally permitted depends on the traffic rules of the country.
🔗 gov.uk • Great Britain Highway Code, Rules 159–169, observation; national guidance example
203. Smartphone
A smartphone is a mobile electronic device that combines telephone, messaging, internet, navigation, camera and application functions. When used in traffic, a smartphone can provide useful functions such as navigation or hands-free communication but can also create significant visual, manual and mental distraction.
Drivers should avoid handling or looking at a smartphone while driving. Where its use is permitted, the device should be positioned and operated in accordance with local traffic rules and without interfering with safe control of the vehicle.
Wikimedia.org • D'Vaughn Bell • CC BY-SA
Why is smartphone use dangerous while driving?
Using a smartphone can take the driver's eyes off the road, hands away from the controls and attention away from traffic. Reading messages, typing or selecting apps can therefore significantly increase distraction.
🔗 gov.uk • Great Britain Highway Code, Rules 159–169, observation; national guidance example
Is hands-free smartphone use completely safe?
No. Hands-free operation removes the need to hold the device but conversations, navigation changes and other interactions can still distract the driver.
🔗 gov.uk • Great Britain Highway Code, Rules 159–169, observation; national guidance example
204. GPS
GPS (Global Positioning System) is a satellite-based positioning and navigation system that allows a compatible device to determine its location. In vehicles, GPS navigation can combine positioning information with digital maps to calculate routes and provide visual or spoken directions.
Drivers should preferably set their destination before starting the journey and avoid unnecessary interaction with the navigation system while driving. GPS directions are advisory and should never be followed when they conflict with traffic signs, road rules or actual road conditions.
Wikimedia.org • ines s. • CC BY
What does GPS do in a vehicle?
A GPS receiver helps determine the vehicle’s position from satellite signals. Navigation software combines that position with digital maps to calculate routes and give directions. GPS positioning and the map or routing information are separate parts of the system.
Should you program a GPS while driving?
It is safer to enter the destination and adjust the route before starting the journey. If significant changes are needed, stop in a safe and permitted place rather than becoming distracted while driving.
🔗 gov.uk • Great Britain Highway Code, Rules 159–169, observation; national guidance example
205. Brake
A brake is a vehicle system used to reduce speed, bring the vehicle to a stop or keep it stationary. Most road vehicles use friction brakes at the wheels, while electric and hybrid vehicles may also use regenerative braking to recover energy while slowing down.
The braking system must remain in good working condition. Worn brake components, overheating, mechanical faults or reduced tyre grip can increase braking distance and reduce the driver's ability to control the vehicle safely.
Wikimedia.org • Andrea Volpato • CC BY-SA
Can brakes become less effective when they overheat?
Yes. Prolonged or repeated heavy braking can cause brake fade, reducing braking effectiveness. On long descents, appropriate gear selection and engine braking can help reduce excessive use of the service brakes.
🔗 hella.com • HELLA, brake-fluid function, MIN/MAX, leak/wear checks
🔗 gov.uk • Great Britain Highway Code, Annex 6, brakes and steering; national guidance example
206. Handbrake
A handbrake, commonly called the parking brake, is a braking system used to keep a stationary vehicle from moving after it has been parked. Traditional systems use a hand-operated lever, while modern vehicles may use a foot-operated or electronic parking brake.
The parking brake should be applied securely whenever the vehicle is parked, particularly on a slope. It operates separately from the normal service brake so that the vehicle can remain stationary even when the driver is absent.
Wikimedia.org • CC BY-SA
Should you use the handbrake every time you park?
Yes. The parking brake should normally be applied whenever the vehicle is parked so that it remains securely stationary. Selecting an appropriate gear or transmission position provides additional security but does not replace the parking brake.
🔗 hella.com • HELLA, brake-fluid function, MIN/MAX, leak/wear checks
🔗 gov.uk • Great Britain Highway Code, Annex 6, brakes and steering; national guidance example
207. Brake fluid
Brake fluid is a hydraulic fluid used in many vehicle braking systems to transmit force from the brake pedal through the hydraulic system to the brakes at the wheels. It must withstand high temperatures and maintain suitable hydraulic properties for reliable braking.
The brake-fluid level and condition should be checked according to the vehicle manufacturer's instructions. Only the specified type of brake fluid should be used, because incompatible or contaminated fluid can impair braking-system performance.
Wikimedia.org • Frettie • CC BY
What does brake fluid do?
Brake fluid transmits hydraulic pressure from the driver's brake input to the braking mechanisms at the wheels, allowing the vehicle to slow or stop.
🔗 hella.com • HELLA, brake-fluid function, MIN/MAX, leak/wear checks
🔗 gov.uk • Great Britain Highway Code, Annex 6, brakes and steering; national guidance example
What does a low brake-fluid level mean?
A low level can indicate wear, a leak or another brake-system problem. Follow the handbook’s warning instructions and have the cause checked, rather than merely topping up. If braking is affected or a stop/brake warning appears, stop safely and arrange appropriate help.
🔗 hella.com • HELLA, brake-fluid function, MIN/MAX, leak/wear checks
🔗 gov.uk • Great Britain Highway Code, Annex 6, brakes and steering; national guidance example
208. Tyres
Tyres are the rubber components fitted around a vehicle's wheels that provide contact with the road. They transmit braking, acceleration and steering forces and play an important role in vehicle stability and road holding.
Tyres should have sufficient tread depth, correct pressure and no serious damage or excessive wear. Drivers should use tyres that are suitable for the vehicle and regularly check their condition, particularly before long journeys or driving in difficult weather.
Wikimedia.org • Ambiguous • CC BY
Why are tyres important for road safety?
Tyres are the vehicle's contact with the road and transmit the forces required for steering, acceleration and braking. Their condition and available grip therefore directly affect vehicle control.
🔗 michelin.co.uk • Michelin, tyre sidewall markings and sizing
🔗 michelin.co.uk • Michelin, winter tyres, conditions and markings
🔗 gov.uk • Great Britain Highway Code, Annex 6, tyres and pressures; national guidance example
🔗 gov.uk • Great Britain Highway Code, Rules 228–231, snow and ice; national guidance example
Should tyres on the same axle match?
Requirements vary between countries, but tyres fitted to the same axle should be compatible in dimensions, construction and performance. National rules may impose specific matching requirements.
🔗 michelin.co.uk • Michelin, tyre sidewall markings and sizing
🔗 michelin.co.uk • Michelin, winter tyres, conditions and markings
🔗 gov.uk • Great Britain Highway Code, Annex 6, tyres and pressures; national guidance example
🔗 gov.uk • Great Britain Highway Code, Rules 228–231, snow and ice; national guidance example
209. Tyre code
A tyre code is the series of letters and numbers marked on a tyre's sidewall that identifies important characteristics such as tyre width, aspect ratio, construction, wheel diameter, load capacity and speed rating. A typical example is 205/55 R16 91V.
Drivers should use tyres whose specifications are suitable for the vehicle. The required tyre sizes and ratings can normally be found in the vehicle handbook, certificate of conformity or other manufacturer information.
Wikimedia.org • F l a n k e r • CC BY
What does a tyre code such as 205/55 R16 mean?
205 indicates the nominal tyre width in millimetres, 55 is the aspect ratio between sidewall height and tyre width, R indicates radial construction and 16 indicates the diameter of the wheel rim in inches.
🔗 michelin.co.uk • Michelin, tyre sidewall markings and sizing
🔗 michelin.co.uk • Michelin, winter tyres, conditions and markings
🔗 gov.uk • Great Britain Highway Code, Annex 6, tyres and pressures; national guidance example
🔗 gov.uk • Great Britain Highway Code, Rules 228–231, snow and ice; national guidance example
What other markings can appear on a tyre?
Tyres can carry additional markings indicating approval, manufacturer information, production date, suitability for winter conditions, reinforced construction or other technical characteristics. The exact markings depend on the tyre type and applicable standards.
🔗 michelin.co.uk • Michelin, tyre sidewall markings and sizing
🔗 michelin.co.uk • Michelin, winter tyres, conditions and markings
🔗 gov.uk • Great Britain Highway Code, Annex 6, tyres and pressures; national guidance example
🔗 gov.uk • Great Britain Highway Code, Rules 228–231, snow and ice; national guidance example
210. Winter tyres
Winter tyres are tyres designed to provide improved traction and braking performance in cold weather, snow and other winter conditions. Their tread pattern and rubber compound are designed to remain effective at lower temperatures and provide better grip than ordinary summer tyres in appropriate winter conditions.
Winter tyres can be identified by markings on the sidewall. The 3PMSF symbol, showing a snowflake inside a three-peaked mountain, indicates that the tyre has met specified performance requirements for severe snow conditions.
Wikimedia.org • A7N8X • CC BY-SA
Are winter tyres compulsory everywhere?
No. Some countries require winter tyres during particular months or whenever winter conditions occur, while others have no general requirement. Drivers travelling abroad should check the rules of every country on their route.
🔗 michelin.co.uk • Michelin, tyre sidewall markings and sizing
🔗 michelin.co.uk • Michelin, winter tyres, conditions and markings
🔗 gov.uk • Great Britain Highway Code, Annex 6, tyres and pressures; national guidance example
🔗 gov.uk • Great Britain Highway Code, Rules 228–231, snow and ice; national guidance example
211. Tyre pressure
Tyre pressure is the amount of air pressure inside a vehicle's tyre. Correct tyre pressure helps the tyre maintain its intended shape and contact with the road and is important for handling, braking, tyre wear and fuel consumption.
Tyre pressure should be checked regularly and adjusted to the pressure specified by the vehicle manufacturer. The recommended pressure can vary according to the vehicle, tyre size and load, and the front and rear tyres may require different pressures.
Wikimedia.org • JEG14 • CC0
Why is correct tyre pressure important?
Correct tyre pressure helps provide predictable handling, braking and tyre wear. Incorrect pressure can reduce performance, increase tyre wear and increase fuel consumption.
🔗 michelin.co.uk • Michelin, tyre sidewall markings and sizing
🔗 michelin.co.uk • Michelin, winter tyres, conditions and markings
🔗 gov.uk • Great Britain Highway Code, Annex 6, tyres and pressures; national guidance example
🔗 gov.uk • Great Britain Highway Code, Rules 228–231, snow and ice; national guidance example
Should tyre pressure be checked regularly?
Yes. Tyres gradually lose air over time, so their pressure should be checked regularly and before demanding or long journeys. The pressure should be adjusted to the manufacturer's recommended value.
🔗 michelin.co.uk • Michelin, tyre sidewall markings and sizing
🔗 michelin.co.uk • Michelin, winter tyres, conditions and markings
🔗 gov.uk • Great Britain Highway Code, Annex 6, tyres and pressures; national guidance example
🔗 gov.uk • Great Britain Highway Code, Rules 228–231, snow and ice; national guidance example
212. Snow chains
Snow chains are traction devices fitted around vehicle tyres to improve grip on roads covered with snow or ice. They are especially useful on steep or mountainous roads where ordinary tyres may not provide sufficient traction.
Snow chains should be fitted according to the vehicle and chain manufacturer's instructions, normally on the driven wheels. They should be removed when they are no longer needed because driving with chains on clear roads can damage the tyres, chains and road surface.
Wikimedia.org • Oregon Department of Transportation • CC BY
Are snow chains compulsory everywhere in winter?
No. Requirements vary between countries and roads. Some countries require chains to be carried during certain periods or fitted when indicated by traffic signs or winter conditions, while others impose no general requirement.
🔗 michelin.co.uk • Michelin, tyre sidewall markings and sizing
🔗 michelin.co.uk • Michelin, winter tyres, conditions and markings
🔗 gov.uk • Great Britain Highway Code, Annex 6, tyres and pressures; national guidance example
🔗 gov.uk • Great Britain Highway Code, Rules 228–231, snow and ice; national guidance example
213. Bicycle tyre
A bicycle tyre is the rubber tyre fitted around a bicycle wheel and provides contact between the bicycle and the road or other riding surface. Its tread, pressure, width and construction affect grip, rolling resistance, comfort and handling.
Bicycle tyres should be properly inflated and regularly checked for wear, cuts, cracks, embedded objects or other damage. The appropriate tyre type and pressure depend on the bicycle, rider, load and riding conditions.
Wikimedia.org • Ivan Radic • CC BY
Why are bicycle tyres important for safety?
Bicycle tyres provide the grip needed for steering and braking and help absorb irregularities in the road surface. Worn, damaged or incorrectly inflated tyres can reduce control and increase the risk of a puncture or loss of grip.
🔗 michelin.co.uk • Michelin, choosing bicycle tyres, road/off-road tread and intended use
Do all bicycles use the same type of tyre?
No. Choose tyres suited to the bicycle and riding conditions. Road and off-road tyres make different compromises between rolling resistance, grip and puncture protection; mountain-bike tyres typically have more pronounced tread for rough or muddy ground.
🔗 michelin.co.uk • Michelin, choosing bicycle tyres, road/off-road tread and intended use
214. Continuous track
Continuous track is a vehicle propulsion system in which a continuous belt or chain runs around a series of wheels or rollers instead of the vehicle travelling on conventional road wheels. It is commonly used on construction machinery, agricultural vehicles, military vehicles and other machines that need good traction on soft or uneven ground.
Continuous tracks spread the vehicle's weight over a relatively large contact area, which can improve traction and reduce ground pressure. Tracks may be made from metal, rubber or a combination of materials, and their suitability for use on public roads depends on the vehicle and applicable regulations.
Wikimedia.org • Ingolfson • CC0
Can tracked vehicles travel on normal roads?
Some can, subject to the local vehicle and road-use requirements. For example, British rules allow qualifying tracked agricultural vehicles on roads only with rubber or other composite tracks that do not damage the surface. Registration, driver entitlement and other vehicle restrictions must also be checked.
🔗 legislation.gov.uk • UK legislation, special-type vehicles and rubber tracks
🔗 gov.uk • DfT, tractors and tracked vehicles on public roads
215. Gross Vehicle Weight
Gross Vehicle Weight (GVW) is the actual total weight of a vehicle at a particular moment, including the vehicle itself, driver, passengers, fuel, luggage and other cargo. It changes as people or goods are added or removed.
GVW should not be confused with Gross Vehicle Weight Rating (GVWR) or Maximum Authorised Mass (MAM), which is the maximum permitted total weight specified for the vehicle. The actual gross vehicle weight must not exceed that permitted maximum.
What does Gross Vehicle Weight include?
The actual laden mass includes the vehicle, occupants, fuel, luggage, cargo and equipment being carried. Be careful with the term Gross Vehicle Weight: some authorities, including British guidance, use GVW for a maximum authorised weight rather than the actual mass at that moment. Check the definition on the document.
🔗 ecfr.gov • US 49 CFR 571.3, GVWR/GCWR manufacturer definitions; US example
🔗 gov.uk • GOV.UK, vehicle weights explained, MAM/GVW and down-plating; British example
Why is Gross Vehicle Weight important?
Actual loaded mass and the permitted ratings both matter. Stay within applicable total, axle, tyre and combination limits, and secure and distribute the load correctly. Do not assume that a figure labelled GVW always means the vehicle’s current measured mass.
🔗 ecfr.gov • US 49 CFR 571.3, GVWR/GCWR manufacturer definitions; US example
🔗 gov.uk • GOV.UK, vehicle weights explained, MAM/GVW and down-plating; British example
216. Gross Vehicle Weight Rating
Gross Vehicle Weight Rating (GVWR) is the maximum total weight at which a vehicle is designed or approved to operate when fully loaded. It includes the vehicle itself together with the driver, passengers, fuel, luggage, cargo and other equipment carried by the vehicle.
GVWR is a fixed maximum value and should not be confused with Gross Vehicle Weight (GVW), which is the vehicle's actual weight at a particular moment. The actual loaded weight of the vehicle must not exceed its permitted maximum.
What does GVWR include?
GVWR is the loaded-weight rating specified by the manufacturer for a single vehicle. It covers the vehicle and everything carried, including occupants, fuel and cargo. The legal mass allowed on a particular journey may also be limited by registration, axle, road or other rules.
🔗 ecfr.gov • US 49 CFR 571.3, GVWR/GCWR manufacturer definitions; US example
🔗 gov.uk • GOV.UK, vehicle weights explained, MAM/GVW and down-plating; British example
Why is GVWR important?
GVWR helps identify the manufacturer’s loading limit and can be relevant to vehicle and licensing classifications. Check every applicable limit: a lower plated, axle, tyre or road limit may also apply. Staying below one total rating does not excuse an overloaded axle or an insecure load.
🔗 ecfr.gov • US 49 CFR 571.3, GVWR/GCWR manufacturer definitions; US example
🔗 gov.uk • GOV.UK, vehicle weights explained, MAM/GVW and down-plating; British example
217. Weigh station
A weigh station is a roadside facility where trucks and other heavy vehicles can be weighed to check whether their total vehicle weight and axle loads comply with legal limits. Some stations also support inspections of vehicle documents, load security or other commercial-vehicle requirements.
Weighing may be performed while a vehicle is stationary or by using Weigh-In-Motion technology that estimates vehicle and axle weights as the vehicle travels over sensors in the road. Vehicles suspected of being overloaded may then be directed to a precise weighing facility.
Wikimedia.org • Famartin • CC BY-SA
Why are overloaded vehicles checked?
Weight checks enforce the applicable vehicle and axle limits and identify overloading. Excess loading can affect tyres, handling and braking. The load must also be distributed and secured correctly; compliance with a total-mass limit alone is not enough.
🔗 ecfr.gov • US 49 CFR 571.3, GVWR/GCWR manufacturer definitions; US example
🔗 gov.uk • GOV.UK, vehicle weights explained, MAM/GVW and down-plating; British example
218. Cargo
Cargo is the goods, materials, equipment or other items carried by a vehicle or trailer. Cargo can range from personal luggage and bicycles to commercial goods, machinery or bulk materials.
Cargo must be positioned and secured so that it cannot shift, fall from the vehicle, interfere with the driver's visibility or affect vehicle stability. The total load must also remain within the vehicle's permitted weight and axle-load limits.
Wikimedia.org • Daniel Case • CC BY-SA
Why must cargo be secured?
Unsecured cargo can move during acceleration, braking or cornering and can affect vehicle stability or fall onto the road. Proper securing protects the occupants, other road users and the cargo itself.
🔗 ecfr.gov • US 49 CFR 571.3, GVWR/GCWR manufacturer definitions; US example
🔗 gov.uk • GOV.UK, vehicle weights explained, MAM/GVW and down-plating; British example
Can cargo extend beyond a vehicle?
In some circumstances it can, but national rules normally limit how far a load may project beyond the front, rear or sides of a vehicle and may require projecting loads to be specially marked.
🔗 ecfr.gov • US 49 CFR 571.3, GVWR/GCWR manufacturer definitions; US example
🔗 gov.uk • GOV.UK, vehicle weights explained, MAM/GVW and down-plating; British example
219. Car body
A car body, also called bodywork, is the outer structure of a car that surrounds the passenger and luggage compartments and gives the vehicle its shape. It includes components such as the roof, doors, bonnet, boot lid, wings, body panels and, on many modern cars, load-bearing structural sections.
The car body helps protect occupants and supports components such as doors, windows, lights and bumpers. Damage, corrosion or poorly repaired structural sections can reduce the vehicle's safety and should be repaired correctly.
Wikimedia.org • Cjp24 • CC BY-SA
Why is the condition of the car body important?
The body helps protect occupants and supports many vehicle components. Serious corrosion, deformation, loose panels or structural damage can reduce crash protection or create hazards for other road users.
220. Trunk
A trunk, also called a boot or luggage compartment, is the enclosed storage area of a car used for carrying luggage, tools, shopping and other cargo. It is usually located at the rear of the vehicle, although some vehicles have a front storage compartment.
Items carried in the trunk should be positioned securely so that they cannot shift dangerously during braking, acceleration or cornering. Heavy objects should be placed carefully and the vehicle's permitted load and axle limits must not be exceeded.
Wikimedia.org • Atomic Taco • CC BY-SA
Can you overload a car trunk?
No. The combined weight of the vehicle, occupants and cargo must remain within the vehicle's permitted total and axle-load limits. Excessive loading can adversely affect braking, steering and stability.
🔗 ecfr.gov • US 49 CFR 571.3, GVWR/GCWR manufacturer definitions; US example
🔗 gov.uk • GOV.UK, vehicle weights explained, MAM/GVW and down-plating; British example
221. Roof rack
A roof rack is a load-carrying system attached to the roof of a vehicle. It can be used to transport items such as luggage, bicycles, skis, surfboards or a roof box when they cannot conveniently be carried inside the vehicle.
A roof rack and its cargo must be securely attached and must remain within the vehicle manufacturer's permitted roof-load limit. Roof-mounted loads raise the vehicle's centre of gravity and can affect handling, stability, fuel consumption and overall vehicle height.
Wikimedia.org • Matti Blume • CC BY-SA
What can be carried on a roof rack?
A suitable roof rack can carry items such as luggage boxes, bicycles, skis and other equipment, provided the rack and attachments are designed for the load and the vehicle's permitted roof-load limit is respected.
🔗 ecfr.gov • US 49 CFR 571.3, GVWR/GCWR manufacturer definitions; US example
🔗 gov.uk • GOV.UK, vehicle weights explained, MAM/GVW and down-plating; British example
How do you know the maximum roof load?
Check the vehicle manufacturer's specifications and the limits of the roof rack itself. The permitted load can vary significantly between vehicles, and the lowest applicable limit should not be exceeded.
🔗 ecfr.gov • US 49 CFR 571.3, GVWR/GCWR manufacturer definitions; US example
🔗 gov.uk • GOV.UK, vehicle weights explained, MAM/GVW and down-plating; British example
222. Windscreen
A windscreen, also called a windshield, is the transparent front window of a vehicle through which the driver views the road ahead. It also helps protect occupants from wind, rain, debris and other external elements.
The windscreen must provide the driver with a clear and sufficiently undistorted view. Cracks, chips, dirt, stickers or other objects can reduce visibility, particularly when they are located within the area swept by the windscreen wipers.
Wikimedia.org • Vcx • CC BY-SA
Why must windscreen wipers keep the glass clear?
Windscreen wipers remove rain, snow and dirt from the driver's viewing area. A clear windscreen is essential for maintaining adequate forward visibility in poor weather.
223. Emergency hammer
An emergency hammer is a safety tool designed to break certain vehicle windows when normal doors or exits cannot be used during an emergency. It is commonly found in buses, coaches and other passenger vehicles near windows designated as emergency exits.
An emergency hammer should only be used when evacuation through the normal exits is impossible or unsafe. The tool must remain accessible and, where provided for an emergency window, should be used according to the instructions displayed in the vehicle.
Wikimedia.org • Santeri Viinamäki • CC BY-SA
What is an emergency hammer used for?
An emergency hammer is used to break a suitable vehicle window so occupants can escape when normal doors or emergency exits cannot be opened.
Can an emergency hammer break every vehicle window?
No. Vehicle windows can use different types of glazing, and not every window is designed to be broken as an emergency exit. Occupants should use designated emergency windows and follow the instructions provided in the vehicle.
224. Car battery
A car battery is an electrical energy-storage device that supplies power to a vehicle's electrical system. In conventional petrol and diesel cars, the 12-volt starter battery provides the high current needed to start the engine and supplies electrical equipment when the engine or charging system is not providing enough power.
Car batteries gradually lose charge and capacity with age and use. A weak battery can cause slow or unsuccessful starting, electrical problems or warning messages, and the replacement battery should have specifications suitable for the vehicle.
Wikimedia.org • Filipograf • CC BY-SA
What does a car battery do?
A low-voltage vehicle battery powers electrical equipment and control systems. In many combustion-engine vehicles it also supplies the starter motor. In an electric-drive vehicle, the auxiliary battery has a different role from the high-voltage traction battery that supplies propulsion energy.
🔗 afdc.energy.gov • US Department of Energy AFDC, auxiliary versus traction battery
🔗 varta-automotive.com • VARTA, replacing AGM/EFB start-stop batteries
Can any replacement battery be fitted to a car?
No. The battery must have specifications and technology suitable for the vehicle. Cars equipped with start-stop systems, for example, may require AGM or EFB battery technology designed for repeated starting and charging cycles.
🔗 afdc.energy.gov • US Department of Energy AFDC, auxiliary versus traction battery
🔗 varta-automotive.com • VARTA, replacing AGM/EFB start-stop batteries
225. Traction battery
A traction battery is a rechargeable battery that stores electrical energy used to propel an electric or hybrid vehicle. It supplies power to one or more electric traction motors and is normally much larger and more powerful than the vehicle's conventional 12-volt starter battery.
Traction-battery capacity is commonly expressed in kilowatt-hours (kWh) and strongly influences an electric vehicle's driving range. Its performance and usable capacity can gradually decrease with age, charging cycles, temperature and use.
Wikimedia.org • Spielvogel • CC0
What does a traction battery do?
A traction battery stores electrical energy and supplies it to the electric motor or motors that propel the vehicle. In hybrid vehicles it works together with another power source, while in battery-electric vehicles it provides the main source of propulsion energy.
🔗 afdc.energy.gov • US Department of Energy AFDC, all-electric vehicle components
🔗 afdc.energy.gov • US Department of Energy AFDC, fuel-cell electric vehicle components
🔗 afdc.energy.gov • US Department of Energy AFDC, hybrid-electric vehicle components
What does traction-battery capacity mean?
Battery capacity indicates how much electrical energy the battery can store and is commonly expressed in kilowatt-hours (kWh). A larger usable capacity generally allows more electrical energy to be available for driving.
🔗 afdc.energy.gov • US Department of Energy AFDC, all-electric vehicle components
🔗 afdc.energy.gov • US Department of Energy AFDC, fuel-cell electric vehicle components
🔗 afdc.energy.gov • US Department of Energy AFDC, hybrid-electric vehicle components