This set of questions delves into the functioning and mechanics of golf carts. From understanding how golf carts operate and move to exploring the inner workings of golf cart batteries, motors, regenerative braking systems, controllers, and charging systems, these inquiries provide insights into the technical aspects of golf cart functionality. By examining these components and systems, golf cart enthusiasts can gain a deeper understanding of how these vehicles operate and deliver reliable performance on the course.
An electric golf cart is a motorized vehicle used for transportation on golf courses. It runs on batteries and produces zero emissions, making it an eco-friendly option. Electric golf carts provide a smooth and quiet ride, without engine noise or exhaust emissions. They are a popular choice for golfers seeking a clean and efficient mode of transportation on the golf course.
Definition of an Electric Golf Cart: An electric golf cart is a motorized vehicle specifically designed for transportation on golf courses. It operates using batteries as its power source, making it an eco-friendly option compared to gas-powered carts. Electric golf carts offer a cleaner and quieter ride, enhancing the overall golfing experience.
Zero Emissions and Environmental Benefits: One of the key advantages of electric golf carts is their zero emissions feature. They do not produce any exhaust emissions, contributing to a cleaner and healthier environment on the golf course. This eco-friendly aspect aligns with the growing emphasis on sustainability and reducing carbon footprints.
Smooth and Quiet Operation: Electric golf carts run more smoothly and quietly compared to their gas-powered counterparts. The absence of an engine noise and exhaust emissions creates a serene and enjoyable atmosphere on the golf course. Golfers can focus on their game without distractions, appreciating the tranquility that electric golf carts provide.
What is the Range of an Electric Golf Cart
The range of an electric golf cart can vary between 15 to 60 miles, depending on factors such as battery type, terrain, and load. Lithium-ion batteries offer a longer range compared to lead-acid batteries. When choosing an electric golf cart, consider your usage requirements and select a cart with a range that meets your needs.
Range Variation: The range of an electric golf cart typically falls within the range of 15 to 60 miles. However, it is important to note that the actual range can vary depending on several factors. These factors include the type of battery used, the terrain on which the cart is operated, and the load it carries.
Battery Type and Range: The type of battery used in an electric golf cart plays a significant role in determining its range. Lithium-ion batteries are known to offer a longer range compared to lead-acid batteries. This is because lithium-ion batteries have a higher energy density and can store more power, allowing the cart to travel a greater distance on a single charge.
Terrain and Load Considerations: The terrain on which the electric golf cart is operated can also impact its range. Uphill or rough terrains may require more power and reduce the overall range of the cart. Additionally, the load carried by the cart, including passengers and equipment, can affect the range. Heavier loads may result in a shorter range compared to lighter loads.
What Kind of Batteries Do Electric Golf Carts Typically Use
Electric golf carts typically use lead-acid batteries, available in 6-volt, 8-volt, or 12-volt options. The number of batteries required depends on the voltage system of the golf cart, which is usually 36 volts or 48 volts. Alternatively, some electric golf carts utilize lithium-ion batteries, offering benefits such as longer lifespan, lighter weight, and faster charging times.
Lead-Acid Batteries: Lead-acid batteries are the most common type of batteries used in electric golf carts. They are available in 6-volt, 8-volt, or 12-volt options. The number of batteries required depends on the voltage system of the golf cart, which is typically 36 volts or 48 volts. Lead-acid batteries are known for their reliability and affordability, making them a popular choice for many golf cart owners.
Lithium-Ion Batteries: Some electric golf carts utilize lithium-ion batteries. These batteries offer several advantages over lead-acid batteries. They have a longer lifespan, lighter weight, and faster charging times. Lithium-ion batteries also provide consistent power output throughout their cycle, allowing for a more efficient and reliable performance. However, they are generally more expensive than lead-acid batteries.
Considerations for Battery Selection: When choosing the type of battery for an electric golf cart, factors such as budget, usage requirements, and desired performance should be taken into account. Lead-acid batteries are a cost-effective option and suitable for most golf cart applications. On the other hand, lithium-ion batteries are ideal for those seeking enhanced performance, longer lifespan, and faster charging times, although they come at a higher cost.
How Many Batteries Are in an Electric Golf Cart
In an electric golf cart, the number of batteries required can vary. Most carts typically use four, six, or eight batteries, depending on the voltage of the electrical drive system. The voltage system of golf carts is usually 36V or 48V. Batteries with voltages of 6V, 8V, or 12V are commonly used. The number of batteries needed depends on the specific cart’s voltage requirements.
Battery Quantity and Voltage: Electric golf carts typically require four, six, or eight batteries to operate. The number of batteries depends on the voltage of the electrical drive system, which is usually 36V or 48V. Golf cart batteries are available in voltages of 6V, 8V, or 12V. The specific number of batteries needed varies based on the voltage system of the cart.
Voltage System and Battery Selection: The voltage system of an electric golf cart determines the number and configuration of batteries. For example, a 36V cart may require three 12V batteries, while a 48V cart can use six 8V batteries or eight 6V batteries. It is crucial to select the appropriate batteries that match the voltage requirements of the cart to ensure optimal performance.
Can You Convert an Electric Golf Cart to Lithium
Converting an electric golf cart to lithium batteries is possible, but the process can vary depending on the chosen lithium battery option. Factors such as voltage and capacity requirements, as well as compatibility with the golf cart, need to be considered. Researching and consulting with experts is recommended for a successful and safe conversion.
Feasibility of Conversion: Yes, it is possible to convert an electric golf cart to lithium batteries. The process involves replacing the existing lead-acid batteries with lithium batteries. However, the specific steps and requirements may vary depending on the chosen lithium battery option.
Factors to Consider: Before converting to lithium batteries, several factors need to be considered. Firstly, the voltage and capacity requirements of the golf cart should match the specifications of the lithium batteries. It is essential to select the right battery voltage and capacity for optimal performance. Additionally, compatibility with the golf cart’s electrical system and charging mechanism should be ensured.
Research and Expert Consultation: Conducting thorough research and consulting with experts is crucial before undertaking a conversion. Different lithium battery options are available, and understanding their features, benefits, and compatibility with the golf cart is important. Experts can provide valuable guidance on the conversion process, ensuring a safe and successful transition to lithium batteries.
How do golf carts operate?
Golf carts operate using either gas or electric power. Gas-powered carts have battery parts that are run off four large batteries, which are charged every night. Electric golf carts rely on battery packs to store electrical energy, powering an electric motor. The speed of the golf cart is controlled for safe and controlled movement.
Gas-Powered Golf Carts: Gas-powered golf carts operate using a combination of gas and battery power. The batteries provide the necessary energy to run the cart’s electrical components, while the gas engine generates power to charge the batteries as needed. This hybrid system allows for reliable performance and extended driving range.
Electric Golf Carts: Electric golf carts operate solely on battery power. These carts use deep-cycle lead-acid batteries or other battery technologies to store electrical energy. The batteries power an electric motor, which drives the wheels and propels the cart forward. The batteries are charged by plugging the cart into a wall outlet, similar to charging an electric vehicle.
Speed Control: Both gas and electric golf carts have speed control mechanisms in place. Gas-powered carts typically utilize a governor or speed control system to regulate the engine’s power output, ensuring safe and controlled movement. Electric golf carts, on the other hand, rely on a controller that regulates the power sent to the motor, allowing for precise speed control.
Golf carts operate using either gas or electric power. Gas-powered carts utilize a combination of gas and battery power, while electric carts rely solely on battery power. Both types of carts have speed control mechanisms to ensure safe and controlled movement. Whether you choose a gas-powered or electric golf cart, understanding how they operate is essential for a smooth and enjoyable ride on the golf course or any designated area.
How do golf carts move?
Golf carts can move using either electric power or gas power. Electric golf carts have an electric motor connected to rechargeable batteries, which provide the necessary energy to move the cart. Gas-powered golf carts have an internal combustion engine that generates mechanical energy for movement. Both electric and gas-powered golf carts offer reliable and efficient transportation on the golf course or any designated area.
Electric-Powered Golf Carts: Electric golf carts operate using an electric motor connected to rechargeable batteries. These batteries store electrical energy, typically 36 or 48 volts, and provide the necessary power to move the cart. When the accelerator pedal is pressed, the electric motor receives power from the batteries and converts it into mechanical energy. This mechanical energy drives the wheels, propelling the golf cart forward.
Gas-Powered Golf Carts: Gas-powered golf carts utilize an internal combustion engine to generate mechanical energy for movement. These carts are equipped with a gas engine that runs on gasoline or other fuel types. When the accelerator is pressed, the engine combusts the fuel, generating power that is transferred to the wheels through a transmission system. This mechanical energy drives the wheels, allowing the golf cart to move.
Golf carts can move using either electric power or gas power. Electric golf carts rely on rechargeable batteries and an electric motor to convert electrical energy into mechanical energy, propelling the cart forward. Gas-powered golf carts utilize an internal combustion engine that generates mechanical energy to drive the wheels. Whether powered by electricity or gasoline, golf carts provide a convenient and efficient mode of transportation on the golf course or any designated area.
How do golf cart batteries work?
Golf cart batteries, specifically lead-acid batteries, work through a chemical reaction between lead plates and sulfuric acid. This reaction allows electrical energy to be stored and released as needed. When the batteries are charged, the sulfuric acid reacts with the lead plates, converting electrical energy into chemical energy and storing it. During use, the stored chemical energy is converted back into electrical energy, powering the golf cart’s electric motor.
Lead-Acid Batteries: Most golf cart batteries are lead-acid batteries. They consist of lead plates suspended in a sulfuric acid solution. This arrangement enables a chemical reaction between the lead plates and the sulfuric acid, allowing electrical energy to be stored and released as needed.
Charging Process: When the golf cart batteries are charged, a chemical reaction occurs. The sulfuric acid interacts with the lead plates, converting electrical energy into chemical energy. This energy is stored within the battery until it is needed.
Energy Release: During operation, the stored chemical energy is converted back into electrical energy. The reverse chemical reaction between the sulfuric acid and the lead plates releases electrical energy. This energy powers the golf cart’s electric motor, propelling the vehicle forward.
Golf cart batteries, specifically lead-acid batteries, operate through a chemical reaction that allows electrical energy to be stored and released as needed. These batteries play a crucial role in powering golf carts, providing the necessary energy for propulsion. Understanding how golf cart batteries function is essential for maintaining their performance and ensuring a reliable power source.
How does a golf cart motor function?
The motor of a golf cart, whether electric or gas-powered, functions by converting electrical or combustion energy into mechanical motion. In an electric golf cart, the motor converts electrical energy from the batteries into mechanical motion, propelling the cart forward. In a gas-powered golf cart, the motor uses an internal combustion engine to generate mechanical motion through controlled explosions. Both types of motors enable the golf cart to move with efficiency and reliability.
Electric Golf Cart Motor: In an electric golf cart, the motor converts electrical energy stored in the batteries into mechanical motion. When the accelerator pedal is pressed, the controller sends an electrical signal to the motor, prompting it to convert electrical energy into rotational motion. This motion is then transferred to the wheels, propelling the golf cart forward.
Gas-Powered Golf Cart Motor: Gas-powered golf carts employ an internal combustion engine. When the accelerator pedal is pressed, it opens the throttle, allowing a precise mixture of air and fuel to enter the engine’s combustion chamber. The spark plug ignites the fuel-air mixture, resulting in controlled explosions. These explosions generate rotational motion, which is transmitted to the wheels through a drivetrain, propelling the golf cart forward.
Golf cart motors, whether electric or gas-powered, play a vital role in powering the vehicles. Electric motors convert electrical energy into mechanical motion, while gas-powered motors utilize internal combustion engines to generate rotational motion. Understanding the mechanics of golf cart motors enhances our appreciation of their functionality and enables us to make informed decisions when it comes to maintaining and optimizing their performance.
How does regenerative braking work in golf carts?
Regenerative braking in golf carts works by utilizing the electric motor as a generator. When the brakes are applied, the electric motor converts the kinetic energy generated during braking into electrical energy. This electrical energy is then sent back to the battery pack for recharging, contributing to increased energy efficiency and extended battery life.
Electric Golf Carts: In electric golf carts, regenerative braking operates by utilizing the electric motor as a generator. When the driver applies the brakes, the electric motor switches its function from providing power to generating electricity. This transformation allows the motor to capture the kinetic energy generated during braking.
Conversion of Kinetic Energy: As the golf cart decelerates, the rotation of the wheels drives the electric motor, causing it to act as a generator. This process converts the mechanical energy from the wheels into electrical energy. The generated electrical energy is then directed back to the battery pack for recharging.
Energy Efficiency and Battery Life: Regenerative braking in golf carts contributes to increased energy efficiency and extended battery life. By capturing and converting the kinetic energy during braking, the system reduces energy waste and allows for the recovery of power that would otherwise be lost. This not only helps optimize the golf cart’s overall energy consumption but also prolongs
How do golf cart controllers work?
A golf cart controller is an integral part of the vehicle, responsible for managing the speed and power delivery of the electric motor. It measures the current and battery voltage to adjust the speed of the golf cart. The controller also monitors the motor’s overall state and generates signals to match the alternating currents required. By regulating the current and voltage, the controller ensures efficient and controlled operation of the golf cart.
Speed Control: A golf cart controller is responsible for managing the vehicle’s speed. It receives input from the accelerator pedal or throttle, translating it into adjustments in current and voltage supplied to the motor. By modulating the power output, the controller governs the speed of the golf cart, allowing for safe and controlled movement.
Current and Voltage Regulation: The controller measures the current flowing from the batteries and monitors the battery voltage. Based on these measurements, it regulates the amount of current and voltage delivered to the motor. This regulation ensures that the motor receives the appropriate power for efficient operation, optimizing performance and extending battery life.
Signal Generation: Golf cart controllers generate signals to match the alternating currents required by the motor. They convert the direct current (DC) power from the batteries into alternating current (AC) signals that match the motor’s needs. This signal generation ensures smooth and efficient motor operation, reducing noise and providing optimal power delivery.
Golf cart controllers are vital components that regulate the speed and power delivery of the electric motor. By measuring current and voltage, adjusting power output, and generating appropriate signals, controllers ensure efficient and controlled operation of the golf cart. Understanding the functioning of golf cart controllers enhances our appreciation of their role in providing a smooth and enjoyable ride on the golf course or any designated area.
How does a golf cart charging system function?
The charging system of a golf cart functions by replenishing the energy stored in the batteries. In electric golf carts, a charger converts AC power into DC power, which is then used to charge the batteries. Gas golf carts utilize alternative methods such as regenerative braking to convert kinetic energy into electrical energy for battery charging.
Electric Golf Carts: In electric golf carts, the charging system consists of a charger connected to the batteries. The charger converts AC (alternating current) power from an outlet into DC (direct current) power suitable for charging the batteries. It regulates the charging process by monitoring the battery voltage and adjusting the charging current accordingly. This ensures safe and efficient charging, optimizing battery performance.
Gas Golf Carts: Gas-powered golf carts do not have a traditional charging system like electric golf carts. Instead, they employ alternative methods to charge the battery. One such method is regenerative braking, where the kinetic energy generated during braking is converted into electrical energy. This energy is then stored in the battery for later use.
The charging system of a golf cart plays a crucial role in maintaining the battery’s energy levels. Electric golf carts rely on chargers to convert AC power into DC power for efficient battery charging. On the other hand, gas golf carts utilize alternative methods such as regenerative braking to convert kinetic energy into electrical energy for battery charging. Understanding the functioning of the golf cart charging system allows us to make informed decisions regarding battery maintenance and optimize the performance of our golf carts.
FAQs
How Maintenance and Battery Upgrades Improve Electric Golf Cart Reliability
Regular maintenance and battery upgrades are crucial for improving the reliability of electric golf carts. Maintenance tasks include cleaning and inspecting the batteries, checking tire pressure, and ensuring the electrical components are in good condition. Upgrading to lithium batteries can enhance performance, increase battery life, and provide a more consistent power supply, improving the overall reliability of the golf cart.
Maintenance for Reliability: Regular maintenance plays a vital role in enhancing the reliability of electric golf carts. Tasks such as cleaning and inspecting the batteries, checking tire pressure, and ensuring the electrical components are in good condition help prevent issues and ensure optimal performance. By addressing potential problems proactively, the reliability of the golf cart is improved.
Battery Upgrades for Performance: Upgrading the batteries of an electric golf cart can have a significant impact on its reliability. Transitioning from traditional lead-acid batteries to lithium batteries offers benefits such as increased performance, longer battery life, and a more consistent power supply. Lithium batteries provide a higher energy density and faster charging times, resulting in improved reliability and a better overall golf cart experience.
How Tire Maintenance Impacts Electric Golf Cart Performance and Efficiency
Proper tire maintenance is essential for optimizing the performance and efficiency of electric golf carts. Regular tasks such as checking tire pressure, ensuring proper alignment, and inspecting for wear and damage can contribute to the golf cart’s maximum performance and high speed. Adequate tire maintenance reduces rolling resistance, improves traction, and enhances overall efficiency.
Tire Pressure and Performance: Regularly checking and maintaining the proper tire pressure is essential. Adequate tire pressure ensures optimal contact with the ground, improving traction and maneuverability. It also reduces rolling resistance, allowing the golf cart to move more efficiently and smoothly.
Alignment and Efficiency: Proper tire and wheel alignment are vital for maximizing the efficiency of an electric golf cart. Misaligned tires can cause uneven wear, increased rolling resistance, and decreased efficiency. Regular alignment checks and adjustments help ensure that the tires are properly aligned, improving the overall efficiency of the golf cart.
Wear and Damage Prevention: Inspecting the tires for wear and damage is important. Worn-out or damaged tires can affect the performance and safety of the golf cart. Regular inspections allow for early detection of any issues, allowing for timely repairs or replacements and maintaining the optimal performance and efficiency of the electric golf cart.
What is Voltage Drop and How Do Lithium Batteries Differ from Lead-Acid
Voltage drop is the reduction in voltage that occurs when current flows through a conductor or component. In the context of batteries, lithium batteries differ from lead-acid batteries in terms of their voltage drop characteristics. Lithium batteries maintain a more consistent voltage throughout the discharge cycle, while lead-acid batteries experience a significant drop in voltage as they discharge.
Voltage Drop Explained: Voltage drop refers to the reduction in voltage that occurs when current flows through a conductor or component. It is a natural phenomenon that can affect the performance and efficiency of electrical systems. In the context of batteries, voltage drop can impact the available power output and the overall performance of the battery.
Lithium Batteries and Voltage Drop: Lithium batteries exhibit a distinct characteristic when it comes to voltage drop. Throughout the discharge cycle, lithium batteries maintain a more consistent voltage, providing a stable power supply. This means that the voltage remains relatively unchanged until the battery is almost fully discharged. The consistent voltage of lithium batteries contributes to their efficient and reliable performance.
Lead-Acid Batteries and Voltage Drop: In contrast, lead-acid batteries experience a significant drop in voltage as they discharge. The voltage gradually decreases as the battery delivers power, resulting in a noticeable reduction in available power output. This voltage drop can affect the performance and efficiency of lead-acid batteries, especially in applications where a consistent power supply is required.
What is the Charging Time Difference Between Lithium and Lead-Acid Batteries
The charging time difference between lithium and lead-acid batteries is notable. While lithium batteries can be fully charged in just minutes to a couple of hours, lead-acid batteries typically require longer charging times, ranging from 6 to 12 hours. This variation in charging time is attributed to the distinct chemical compositions and charging characteristics of these battery types.
Lithium Batteries and Charging Time: Lithium batteries offer a significant advantage when it comes to charging time. With the right charger, they can be fully charged in just minutes to a couple of hours. This fast charging capability allows for quick turnaround times and minimizes downtime, making lithium batteries ideal for applications that require frequent usage or rapid recharging.
Lead-Acid Batteries and Charging Time: In contrast, lead-acid batteries generally require longer charging times. The charging process for lead-acid batteries typically takes around 6 to 12 hours to complete. This longer charging time is due to the chemical composition and internal resistance of lead-acid batteries, which necessitate a slower charging rate to ensure optimal performance and battery life.
How Do Lithium Batteries Compare to Lead-Acid in Range Per Charge
When comparing lithium batteries to lead-acid batteries in terms of range per charge, lithium batteries tend to have the advantage. With their higher energy density, lithium batteries can store more energy in a smaller and lighter package. This translates to a longer range on a single charge for electric vehicles or devices powered by lithium batteries compared to those powered by lead-acid batteries.
Lithium Batteries and Range per Charge: Lithium batteries have a higher energy density, which means they can store more energy per unit weight or volume compared to lead-acid batteries. This higher energy density allows electric vehicles or devices powered by lithium batteries to achieve a longer range on a single charge. The lightweight and compact nature of lithium batteries also contribute to improved efficiency and increased range.
Lead-Acid Batteries and Range per Charge: Lead-acid batteries, although widely used in various applications, have a lower energy density compared to lithium batteries. This lower energy density limits the amount of energy that can be stored in a lead-acid battery, resulting in a shorter range per charge. Additionally, the heavier weight and larger size of lead-acid batteries can impact the overall efficiency and range of electric vehicles or devices.
What Are Common Issues with Electric Golf Cart Lead-Acid Batteries
Common issues with electric golf cart lead-acid batteries include acid leaking, buildup, and corrosion around the battery terminals. The cart may also experience a noticeable decrease in charge retention, a drop in acceleration even after a charge, and longer charging times. These issues can impact the performance and lifespan of the lead-acid batteries.
Acid Leaking, Buildup, and Corrosion: One of the common issues with lead-acid batteries is acid leaking, buildup, and corrosion around the battery terminals. This can occur due to factors like overcharging, improper maintenance, or age-related wear. Acid leaks and corrosion can lead to poor electrical connections, reduced battery efficiency, and potential damage to the surrounding components. Regular cleaning and inspection of the battery terminals can help prevent these issues.
Decreased Charge Retention: Another common issue is a noticeable decrease in charge retention. Lead-acid batteries may lose their charge faster than usual, resulting in reduced range and performance. Factors such as age, sulfation, and internal resistance can contribute to this issue. Regular maintenance, including proper charging and periodic equalization, can help improve charge retention and extend the battery’s lifespan.
Reduced Acceleration: Even after a full charge, electric golf carts with lead-acid batteries may experience a drop in acceleration. This can be attributed to factors like battery capacity degradation, internal resistance, or worn-out battery cells. Regular battery testing and replacement of faulty or worn-out cells can help restore the cart’s acceleration performance.
What is the function of acceleration control in an electric golf cart?
Acceleration control in an electric golf cart regulates the speed by managing the power delivered to the motor. This is typically done via a throttle or pedal, which adjusts the motor’s speed and provides a smooth and responsive acceleration experience.
How do the components of an electric golf cart work together?
In an electric golf cart, the main components include the battery pack, motor, controller, and acceleration pedal. The battery supplies electrical energy to the motor through the controller. The controller regulates the power flow based on the acceleration pedal input, enabling smooth and controlled movement.
How does the power supply system in an electric golf cart operate?
The power supply system in an electric golf cart consists of a battery pack that stores electrical energy. When the accelerator is pressed, the battery sends power to the motor via the controller. The controller adjusts the power based on the pedal position, controlling the cart’s speed and acceleration.
What are the advantages of owning an electric golf cart?
Owning an electric golf cart offers advantages such as lower operating costs, reduced maintenance, quiet operation, and zero emissions. They are eco-friendly, cost-effective for regular use, and can be charged at home, providing convenience and efficiency.
How is direction control achieved in electric golf carts?
Direction control in electric golf carts is managed via a forward-reverse switch or lever that changes the direction of the motor’s rotation. This switch is connected to a contactor or relay that directs the current flow, allowing the cart to move forward or backward.
What type of battery packs do electric golf carts use?
Electric golf carts typically use lead-acid or lithium-ion battery packs. Lead-acid packs come in configurations of 6V, 8V, or 12V batteries, while lithium-ion packs are often available as integrated units with higher energy density and longer life.
What are the advantages of lithium-ion battery packs over lead-acid batteries in electric golf carts?
Lithium-ion battery packs offer several advantages over lead-acid batteries, including longer lifespan, faster charging times, lighter weight, and higher energy density. They also require less maintenance and provide more consistent power output over their life.
What types of motors are used in electric golf carts?
Electric golf carts use either DC (direct current) motors or AC (alternating current) motors. DC motors are commonly used in older models due to their simplicity and cost-effectiveness, while AC motors are becoming popular for their efficiency and smooth performance.
What are the main components of electric golf carts?
The main components of electric golf carts include the battery pack, electric motor, controller, acceleration pedal, braking system, and chassis. Additional components may include a forward-reverse switch, steering mechanism, and various accessories for comfort and functionality.
Why are AC motors becoming popular in modern golf carts?
AC motors are gaining popularity in modern golf carts due to their higher efficiency, smoother acceleration, and better performance in various conditions. They offer more torque, improved speed control, and greater reliability compared to traditional DC motors, making them suitable for advanced golf cart designs.
