Batteries
What is the main job of a battery in an EV?
To power the motor.
What does a gear do?
t changes speed, torque, or direction of motion.
What provides energy to the motor?
The battery.
What do wheels do for an EV?
They help the vehicle roll along the surface.
What force opposes the motion of an EV as it rolls across the floor?
Friction.
What type of energy is stored in a battery?
Chemical energy.
If you want your EV to move faster, should you generally use a higher speed ratio or a higher torque ratio?
A higher speed ratio.
What type of energy does the motor convert electrical energy into?
Mechanical (rotational) energy.
Which generally travels farther per wheel revolution: a large wheel or a small wheel?
A large wheel.
Two EVs travel the same distance. EV A accelerates quickly but slows down before the finish. EV B moves at a constant speed. Which one will have a more predictable stopping distance?
EV B, because consistent speed makes calibration easier.
Why should you use the same battery during testing whenever possible?
To keep the vehicle's performance consistent and make calibration more accurate.
Your EV can barely start moving because it is geared too fast. What should you do?
Increase the gear reduction (more torque).
Your battery voltage drops during the day. What happens to your EV's? (think speed and distance)
It generally runs slower and may travel a smaller distance.
Two wheels have the same diameter, but one is made of rubber and the other is smooth plastic. Which one is more likely to provide better traction?
The rubber wheel.
An EV has twice the mass of another EV, but both travel at the same speed. Which one has more momentum?
The heavier EV has more momentum.
Your EV traveled 5.0 m yesterday but only 4.7 m today using the same settings. Nothing on the vehicle has changed. What is the most likely cause?
The battery has discharged (or its voltage is lower), reducing the motor's speed.
You change your EV from a 2:1 gear reduction to a 4:1 gear reduction. What will most likely happen?
The EV will have more torque but a lower top speed.
Is a faster motor always good for an EV?
No, sometimes fast motors don't have enough torque to accelerate.
One wheel is slightly crooked. How will this most likely affect the EV?
It may drift or turn instead of traveling straight.
An EV overshoots the target by the same amount every run. Is this a problem with consistency or calibration? What should the team do?
It is mainly a calibration problem. The team should adjust their timing/distance settings based on the consistent error.
Why is a consistent battery voltage often more important than simply having the highest possible voltage?
Because consistent voltage leads to consistent motor performance, making the EV easier to calibrate and more accurate
Your EV climbs a small ramp during testing but stalls halfway. You can only change the gear ratio. What change would you make?
Increase the gear reduction to provide more torque.
Your motor is powerful enough to move the EV, but the vehicle barely moves because the wheels keep spinning in place. Should you:
B. The problem is wheel slip, so improving traction or adjusting the drivetrain is more effective than simply increasing motor power.
Why is wheel alignment important in EV?
It reduces friction and helps the vehicle travel consistently and accurately.
Your EV is calibrated perfectly on a smooth floor. At competition, the floor is rougher. The motor runs for the same amount of time. Will the EV likely stop before, after, or at the target? Explain.
Before the target, because increased friction slows the vehicle and reduces how far it travels.