Super Capacitor Bike

this is a lithium-ion cell and this is a supercapacitor both store energy using different methods and a lithium-ion cell can store about 35 times the energy of the capacitor but takes around 45 minutes to safely charge whereas the supercapacitor can be charged in under a minute though supercapacitors have several limitations for a start their lack of energy storage means they probably won't achieve much range in an electric vehicle but also making use of this energy storage is more complex than a lithium battery due to discharge rates with a combustion engine car the amount of power that the engine outputs doesn't depend on how much fuel is in the tank the engine will still run at max power even if it's running on vapors but with an electric car the amount of power that the motor outputs depends on the voltage of the battery so with a fully charged battery you will have more motor power than with a discharge battery however this is nothing in comparison to super capacitors [Music] this graph shows how the voltage of a lithium battery changes as it discharges you can see it holds the voltage relatively constant until the last few percent where it decreases rapidly whereas a super capacitor discharge rate looks like this so if you try to run a regular electric vehicle which is designed for this voltage range on super capacitors you can see there will be some issues mostly the fact it will only be able to use this amount of energy so i'm going to build an electric bike that's specifically designed for super capacitors i started by cnc cutting an aluminium plate which will fit inside my bike frame and carry out the roll of a motor mount i then cut an eight-legged starfish shape which will hold the coils for the motor that's right i'm building my own electric bike motor the next step was to cut the rotor of the motor which will be the spinning part and also hold all of the magnets which were glued into the rotor using epoxy and were orientated in alternating positions so one magnet had its north pole facing up and the next magnet had its south pole facing up and so on whilst the glue was drying i started making the coils out of this .8 millimeter enameled copper wire which will be wound around this 3d printed core using this aluminium template with a 3d printed insert to protect the copper wire i could then fix the template to a solid mount and start winding the coil and yes i'm using my calculator with its answer plus one feature to count the number of coils which i need 150 of and trust me it's not fun losing count after 150 turns of the copper wire i secured the wire with some glue and can remove it from the template then to make sure it doesn't unwind into a nightmare spaghetti monster i added some more glue to secure it all in position then remove the safety wire and we now have a motor coil but how do we get this coil to spin the motor if we connect the coil directly to a supercapacitor it will create a current in the coil which will generate a magnetic field and depending on the polarity of this magnetic field it will attract one of the magnets rotating the motor slightly but to rotate the motor any further the current direction in the coil must be changed by swapping the connections this will then attract the next magnet and must be switched 16 times per rotation of the motor which obviously can't be done manually so we need to make a motor controller the motor controller consists of a few different components but it's essentially a bunch of electronic switches that convert a direct current from the super capacitors into an alternating current for the coil my original plan was to build my own motor controller as you can see here but i managed to order the wrong components for the job so it kind of worked for a few minutes before it gave up i then found one of these brushed motor controllers which can switch the direction of a dc motor and realize i could hack this to produce an alternating current for my coil unfortunately this motor controller isn't capable of regenerative braking but it should be able to power my bike with some help from an external control board and some custom code when riding a bike you've probably never considered the timing of when you press down on your pedals your brain just naturally knows to apply pressure when your foot is at the top and past the center line if you had no reference to where your foot was you would end up applying pressure at the wrong position causing the pedals to either spin backwards or not spin at all this is exactly what the motor controller must deal with as it currently has no method of detecting the position of the magnets and therefore applying random current directions to the coil won't get us anywhere so to tell the motor controller when to apply power to the coil i mounted a bunch of small alternating magnets to the rotor and mounted a magnetic sensor to the motor mount so when the motor spins the sensor will output either a one or a zero depending on the polarity of the nearest small magnet this is like your brain detecting that your right leg is at the top so stop applying pressure to the left pedal and start applying pressure to the right pedal then as your left leg gets to the top stop applying pressure through the right pedal and start applying it through the left and so on so to start the motor i push down on this lever throttle and a signal is sent to this electronics board which holds the motor control code that i've written this then reads the signal from the motor sensor and determines which direction to apply the current to the coil it then sends that information to the motor controller to apply current to the coil and hopefully switches the current every time a new magnet passes now we have a completely diy electric bike motor and controller now because this motor probably won't have much torque i made a huge sprocket for the rear wheel to give it some mechanical advantage and when i went to fit the chain i realized a major design flaw with this motor yup the chain sticks to the motor magnets but fortunately it doesn't take much tension to keep the two apart it's finally time to assemble the super capacitor bank that will power this bike which i chose to use these 2.7 volt 400 farad super capacitors yes you heard that right these are 400 farad capacitors and when soldered in series should store 11 881 joules of energy which sounds like a lot but is roughly the same as an aa battery but let me see you charge your aa battery in two minutes actually don't do that i hold no responsibility for fires caused by rapid charging of your aea batteries also i doubt an a battery would be capable of powering an electric bike now all we need to do is wind the remaining seven coils solder them all together and take this bike for a test ride so the super capacitors are fully charged i am wearing a helmet because the last time i rode this bike with a five kilogram spinning steel just between my legs apparently the irresponsible part was uh the lack of helmet so uh safety first guys right let's plug it in and give it a spin i mean it works [Music] i don't know how much range i have so i'm going to turn around because we are running this bike on capacitors after all the power again i can already tell it's running running very low well that was exciting still have a little bit of power left yeah this is uh this is not great i reckon that's it there we go oh my god so because this speed controller doesn't have regenerative braking capabilities i need a way of charging these super capacitors so what i have here is my lithium ion electric bike battery plugged it straight into my lithium battery charger and then from this it's plugged into the super capacitors down here now obviously this charger isn't designed for charging super capacitors but if i pretend i'm charging a nickel metal hydride or nickel metal uh cadmium i think it is uh i can pretend it's one of those batteries and it will ramp up the power here this is one amp this is the voltage of the capacitors and stop and that's how you charge your super capacitor bike going a bit further this time just to see if we can make it back and we've run out again not great these capacitors are they what about if we what about if i try and run it off of my actual electric bike battery i wonder if that'll work okay so because i don't have a mount on the bike for my battery i've just uh put it in a backpack and i've got this really long lead it works it actually it runs off my uh electric bike battery right let's um this is all right actually fully diy e-bike i can't believe this actually works i know it's not got much power but i feel i feel that i feel quite proud to actually say i've built my own e-bike from scratch like fully from scratch you know like my other e-bikes are sort of modified motors to to fit but this this is an actual fully diy e-bike when i designed this motor controller i made sure to use a board with a memory card option so we can enable data logging to analyze the tests on the left is the voltage of the super capacitors and on the right is the speed of the bike in meters per second during acceleration the voltage drops significantly and the bike only reaches a top speed of 3.5 meters per second before starting to decelerate as the max speed of the motor is determined by the input voltage then after just 99 meters the motor shuts down due to lack of voltage and the bike rolls to a stop but super capacitors aren't designed for long range applications they're designed for rapid charge and discharge situations so i reprogrammed my other homemade electric bike to deal with the lower voltages and gave it a test similar to the previous test its speed is limited by the voltage of the capacitors it just gets to that speed a lot quicker due to its 4 kilowatt motor but the coolest thing about this bike is it has regenerative braking so as i slow down to turn around the voltage of the capacitors increased slightly and i can use this power to accelerate out of the corner again i was also able to charge the capacitors while cycling with the regen braking enabled and then use this power to accelerate again though this isn't ideal so i took the bike to a top of a hill and discharged it completely before riding down the hill the graph on the left shows the voltage of the capacitors and the graph on the right shows the relative altitude of the hill as a percentage surprisingly riding down this hill nearly fully charged the capacitors by the time i reached the bottom and i was able to ride 41 of the distance back up the hill which i think is very impressive if the unpowered resistance of the motor was reduced then this could be a very viable energy recovery system on the topic of energy storage i recently watched a documentary about the invention and evolution of lithium batteries over on curiosity stream curiosity stream is kind of like netflix but for nerds which is way better as there's thousands of movies and tv shows that cover science history technology and many more categories to choose from relating to my interests of engineering energy storage and aircraft there is a great documentary that covers the transportation of the future such as electric aircraft powered by lithium batteries and the engineering struggles behind them did you know to achieve the same energy storage of one kilogram of fossil fuel you would need 25 kilograms of batteries and considering how important weight is in an aircraft it's a very interesting episode to watch you can watch these on your mobile computer browser smart tv and a range of other devices if this interests you as much as it interested me then you can sign up for just 14.99 for a whole year using the code tom stanton or by clicking the link in the description down below thank you to all of my supporters over on patreon.com for making these kind of projects possible and thank you very much for watching this video i guess i'll see you in the next one goodbye

Channel: Tom Stanton

Views: 5,172,027

Keywords: electric bike, bicycle, bike, ebike, physics, engineering, capacitor, super capacitor, engineer, mechanical, lithium, battery, electronics, motor, DIY, homemade

Id: V_f8Q2_Q_J0

Length: 12min 57sec (777 seconds)

Published: Mon Sep 27 2021