32 votes
Accepted

Does an electric vehicle going downhill recover energy?

It depends on how steep the hill is. On a slight hill, the energy added by gravity is still not enough to overcome rolling friction and air resistance, so the car still needs power to maintain speed. ...
  • 1,012
6 votes

Does an electric vehicle going downhill recover energy?

Yes, it can certainly happen. To recharge the battery when going down hill, the free roll speed needs to be greater than the speed you are trying to go. That means going down the same hill may ...
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5 votes
Accepted

What would be needed to make a tesla fastest car in the world?

Maximum speed in a straight line is largely determined by the vehicles maximum power output compared to its drag although once you get past about 200 mph dynamic stability can start to become a ...
  • 15.1k
5 votes
Accepted

Why not use just one electric motor in a car?

One problem with generating electrical energy from a car engine is that the RPMs are constantly changing, and consequently the power output of an electrical generator would vary with engine speed. An ...
  • 3,044
5 votes

Electric go kart

This cannot be answered as is because almost all the critical information is missing. Mechanical Power required to move to the go kart is determined by the force and speed required Motor Power can ...
  • 4,070
5 votes

Is there an upper limit to how fast a self balancing one wheeled vehicle can become while also being able to safely stop?

As an owner of an Airwheel S8™ self balancing scooter (with a seat) that operates similarly to a Segway™, I can offer insight and my own experience. There is an upper limit, which is primarily based ...
  • 6,552
5 votes
Accepted

What happens if an EV motor is stalled?

A stalled motor's cooling fan is not turning, at the same time its windings are dissipating lots of electrical power into heat. The heat ruins the insulation on the wire in the windings, and the ...
4 votes

Does an electric vehicle going downhill recover energy?

The basic equations governing an electric car are reversible, so a simple analysis would say that the battery is getting charged. In the real world, there are more complications. In the case of an ...
4 votes

Does an electric vehicle going downhill recover energy?

ABB train regenerative braking. Some Swiss trains give back energy to the grid upon descending the mountain pass that they previously climbed. The article claims as much of 70% is recovered. I rode ...
3 votes
Accepted

How do you charge 400v battery packs from 120v outlets for EVs?

The additional equipment is onboard the EV in today's crop of electric cars. The charger is part of the vehicle, while the station, formally known as EVSE, Electric Vehicle Service Equipment, ...
  • 6,552
3 votes

V8 electric engine

It is certainly possible as each cylinder could effectively be a solenoid (i'm actually pretty sure I have seen exactly this but can't remember where atm) ....however the reciprocating nature of IC ...
  • 15.1k
3 votes
Accepted

A couple of questions about making an electric hobby car from scratch

Answers to your specific questions: No, voltage converters won't help, at best they will waste 10% of your power. Think about this : they involve transformers. two different windings on a magnetic ...
  • 1,600
3 votes
Accepted

Could a reciprocating engine be powered by electric arc instead of combustion?

Yes, but it would probably be a very poor engine. As you noted in your question, there are huge practical issues with using the arc alone as your power source, compared to using it to ignite the fuel ...
  • 3,211
3 votes

Electric go kart

While DKNguyen's answer is accurate. I believe you're looking for a more holistic answer. Will it move? Absolutely it will move if you give it enough gear reduction. You could move the cart with a ...
  • 1,848
3 votes
Accepted

With ebikes, is there friction from the motor when riding with the electronics turned off?

Different electric assist bikes will present different circumstances. For instance, a standard hub motor (front or rear wheel) will have permanent magnets which react with the iron in the stator. You ...
  • 6,552
2 votes

Battery Swapping in Electric Cars

Advantages: Minimal turnover time Simple, standardized connection Disadvantages: Varying "remaining life" in batteries Overhead of disposing of spent batteries Needs standardization (or better, ...
2 votes

How to calculate the maximum starting traction force for a train with multiple carriages?

The answer to the first part of question is, you're right, you don't concern yourself with the other carriages friction or weight. The second part, you have to consider static friction force on the ...
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2 votes

What are the tradeoffs between using hydraulic motors and electric motors?

You get more free gearing with the hydrostat, and much smaller package and less weight. Take a 60hp diesel and hook it to a hydraulic drive servo. It makes up to 4500 psi peak pressure, or 8 gpm peak ...
  • 4,090
2 votes

What are the tradeoffs between using hydraulic motors and electric motors?

you will find that a generator capable of delivering, say, 10HP (electrical equivalent, 750 watts = 1HP) is very big and heavy and a hydraulic pump with a 10HP rating is smaller and lighter. Similarly,...
2 votes
Accepted

One Wheel Drive utility wagon

I think you're on the right track to not use a solid driven axle, as it will give you problems as you describe. I don't believe that a single wheel drive would be too much of a problem, unless you're ...
  • 6,552
2 votes

One Wheel Drive utility wagon

This isn't a complete answer but may give you some ideas. I think you are correct not to drive only one wheel. The cart looks rather rigid and I can imagine that on rough terrain that one wheel will ...
  • 9,414
2 votes

250W 24V Motors

This is not an answer, it is just pointing out an error in calculations. DC motor torque discrepancy A DC motor at 2750[rpm] and 250[W], outputs $$M=\frac{P}{\omega} = \frac{P}{\frac{2\cdot\pi\cdot n}...
  • 23.6k
2 votes
Accepted

How do electric vehicles' motors run at high speeds above 10000rpm?

A portion of your question contains a portion of the answer. Your squirrel cage motor example is connected to line power, while the typical Tesla motor is not connected to line power. According to a ...
  • 6,552
2 votes
Accepted

Is there an upper limit to how fast a self balancing one wheeled vehicle can become while also being able to safely stop?

No Speed Limit As @fred_dot_u explains, there are stability limits for top speed and for the maximum braking based on the power of the device for a device that is stability controlled and electrically ...
  • 5,272
2 votes

How does a Charging Station stop a charge with an EV connected

I cannot give you a complete answer but since no one else is answering, I'll take a crack. If you want to actually control power to the charging station, you need to use contactors. These are special ...
  • 121
2 votes

What is the approximate horsepower/kW output of a cyclist riding a bike at near ~300km/h?

It's important to realize here that the speed achieved by Denise Meuller would never be possible without the vehicle traveling in front of her. This vehicle created a low-pressure area right behind it....
1 vote

number of electric vehicles that can be charged with specific amount of energy

It would be very unusual to have a wind turbine power a charging station without having a buffering device for energy storage such as an electrolyser or a battery of its own. But if it's a textbook ...
1 vote
Accepted

number of electric vehicles that can be charged with specific amount of energy

There isn't enough information in the question to give a reliable answer. But here are some possible crude answers, just in case you are being tested on basic arithmetic and the relationship between ...
  • 3,711
1 vote

EV AC charging manufacturers

They are not the same, even while they meet the exact same standards minimum. Basically level 1/2 chargers are actually not charging, they just deliver AC power safely to the onboard charger of the ...
  • 21.6k
1 vote
Accepted

Electric engine and transmission

The essential question here is why or why not use a transmission in an electric car. Here are the underlying issues. It is commonly asserted that a DC electric motor is a constant-torque device, ...

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