# How to Build a Supercapacitor Dragster on a Budget?

• Fred404
In summary, a small dc motor can be fed with a supercapacitor to create a power pack for a dragster. The supercapacitor will only deliver 2.7V, so the race car will require another capacitor to provide backup power. It is unclear if a device to charge supercaps is available.
Fred404
Hi all!

I’m currently working on a project for which students will have to build a supercapacitor based dragster.

I saw here and there some videos on how it works but it’s too general to give me hints about components choice. So here I am with my questions, hoping that I’ll get enough answers to go forward with this project ;)

So, here it is:

I want students to build a small dragster (basically very light, made of wood sticks and such, not a big thing!) to organize a contest (drag race) on very small distance (let say about 3 meters max).

As for any school project, the amount of money is limited! No way to build a drag for 50\$ each unfortunately.

Here are the components I was thinking about:

A small dc motor Gikfun DC 3V-6V Motor 2000 RPM

Here are specs:

I was planning to feed it up with supercapacitors only. I was thinking of supercapacitor 2.7V, 10F to build a power pack in parallel if needed.

Here is what I’ve done so far (if I’m not wrong):

Energy stored in the supercapacitor 2.7V/10F

E=1/2.C.U2

E = (1/2)* 10F * 2.722V

E= 36.45 JoulesResistance of the DC motor:

R = U/I

At Maximum Efficiency – according to specs – we have 0.94A for 3V

R = 3V/0.9A = 3.34 ohm
Time of charge tho (sorry, don’t know the translation in English) for this setting:

Tho = R . C = 3.34 ohm x 10F = 33.4 s
So, this means that if tho = 33.4s, after 33.4s, there will only 37% energy left in capacitor.

After 5x tho, the capacitor will be empty.
Energy required for the race:

This is where I think, calculation may be inaccurate cause it depends on the weight of car (the heavier, the more energy needed)

Let say the car is about 150g (0.15 Kg)

F = m x g
F = 0.15 x 9.81 = 1.47 N

For a 3 meters race:

W = F x d
W = 1.47 x 3 = 4.41 J

For the motor, at Max Efficiency, we have 0.94A at 3V (even though the supercapacitor will only deliver 2.7V) for a 5 sec race

P = UI and E = Pt
P = 3 x 0.94 = 2.82W
E = 2.82 x 5 = 14.1 Joules

So, all "energy needed together", this represents an overall total of 4.41 + 14.1 = 18.51 J

According to that, this means that 1 supercapacitor would be enough
But just to have "backup", I can add an extra capacitor in parallel, which should give me twice energy...

So, am I totaly out of field? Does it make sens?

Also, does someone knows if I can buy a device to charge supercapacitors? I've found a diy to build one but it may take too much time for students to build it! So I was wondering if I could find a device that would do the job so that would just have to go to a station to charge their drag!

Thanks for any inputs ;)

Fred

I haven't used supercaps much, but my impression is that they are for low output currents (like real time clock backup), not for high energy applications. I could be wrong about that though. Have you looked in detail at the supercap datasheet to see what it shows for maximum output current?

Fred404 said:
F = m x g
No. The force will be the wheel torque divided by the wheel radius, but can never exceed the tire friction force which is the tire-road friction coefficient times the vertical force acting on the driven wheel. (More info here and here.)

Fred404 said:
So, all "energy needed together", this represents an overall total of 4.41 + 14.1 = 18.51 J
No. The energy needed will be the calculated output energy (4.41 J in the example) divided by the motor efficiency (43.8 % from the chart given), thus 4.41 / 0.438 = 10.14 J.

Thanks for those inputs: I'll check closer for both!
I haven't checked the datasheet for capacitors since I didn't ordered them yet and just check what is avail!

berkeman

## 1. What is a supercapacitor dragster project?

A supercapacitor dragster project is a scientific experiment that involves building a dragster car powered by supercapacitors, which are energy storage devices that can release large amounts of energy quickly. The goal of the project is to create a vehicle that can accelerate quickly and reach high speeds using only supercapacitors as its power source.

## 2. How does a supercapacitor dragster work?

A supercapacitor dragster works by storing electrical energy in the supercapacitors, which are then rapidly discharged to power an electric motor. This allows the dragster to accelerate quickly and reach high speeds without the need for a traditional combustion engine.

## 3. What are the advantages of using supercapacitors in a dragster?

Supercapacitors have several advantages over traditional batteries when used in a dragster. They have a higher power density, meaning they can release energy faster and provide quicker acceleration. They also have a longer lifespan and can be recharged more quickly. Additionally, supercapacitors are more environmentally friendly than batteries as they do not contain toxic materials.

## 4. What are the challenges of building a supercapacitor dragster?

One of the main challenges of building a supercapacitor dragster is finding the right balance between power and energy. Supercapacitors can release energy quickly, but they have a lower energy density compared to batteries, meaning they can't store as much energy. This makes it difficult to design a dragster that can reach high speeds and also have a decent range. Another challenge is the cost of supercapacitors, which can be more expensive than traditional batteries.

## 5. Has a supercapacitor dragster project been successfully built before?

Yes, there have been several successful supercapacitor dragster projects in the past. In 2011, a team from Ohio State University built a supercapacitor-powered dragster that reached speeds of over 160 miles per hour. In 2018, a supercapacitor dragster built by a team from the University of Stuttgart in Germany set a world record by reaching a top speed of 274.02 miles per hour.

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