Building an Electric Bike

[Music] this is my homemade electric bike it isn't powered by a hub motor or add-on kit but instead powered by a large drone motor it's taken me three years to get to this point and I want to share what it took to build an electric bike from scratch so grab a drink sit back and let's read one three years at the time I was studying at university and my housemate Dannie built an electric skateboard using these hobby-grade brushless motors combined with speed controllers designed to radio-controlled cars now I personally prefer two large wheels over four small wheels and one did this setup can be modified for a bike so I purchased a cheap bike from Amazon with a large motor that can be attached to the rear of the frame using a 3d printed mount this motor would then drive the rear wheel via a belt and pulley system where the large rear pulley was also 3d printed and cable tied to the wheel spokes this drivetrain worked well but the cheap speed controller had a slight issue the throttle input controlled the speed of the motor and not the power output which makes sense as it is called a speed controller but the issue is that it will do anything to maintain the speed in but you give it so when climbing a hill if the motor can't maintain the speed that you want it to the speed controller will dump a load of current into the clothes and toast the motor a little after this I didn't want to spend too much money on a project that might not work but I also didn't want to risk ease in the same speed controller and burn out another motor so I purchased a V ESC or vest this speed controller was twice the price of the previous one but I had current-limiting capabilities meaning the motor was essentially never burn out if I set the limit correctly also I didn't want to buy another motor and therefore ended up rewinding the motor by hand which is why the coils in the original electric bike video looked different to the original motor coils and it was this rewound motor and Vesak setup that powered the bike in my first electric bike video back in 2017 but there were some fundamental flaws of the design the first being the pulley ratio was far too high meaning the acceleration wasn't great on the plus side at a top speed of 34 miles per hour I think 3d printed a new larger pulley which produced more torque at the rear wheel this would also reduce the top speed and this began my quest for more power so I built this ridiculous setup yep that's two motors attached to a bag rack above the rear wheel these two motors will link together via a single belt to drive the rear wheel but it never rode more than a couple hundred meters due to an unforeseen issue as this motor applied talked to the belt it would increase attention here but also decrease attention here meaning the reduced tension around the second pulley caused the belt to skip rendering the second motor useless and then made this mount where there's only one output pulley driving the main belt and a secondary small about connecting the two motors this setup works surprisingly well and had lots of pound [Music] but the biggest problem that they set up was not being able to tension the smaller belt joining two motors together at the outer case of the motors would spin also surely afterwards one of the two speed controllers died fortunately I was contacted by a company called tramper boards who are working with Benjamin Vedder on a new speed controller called the vests six this new speed controller could handle a lot more current meaning I could use one large single motor rather than two smaller motors and get a similar power output I also invested in some lithium-ion cells to build a 44 volts 15 amp hour battery pack and built apart 3d printed part aluminium motor mount which was pretty similar to the version one electric bike but with around three times the power it's also had for dinner two breaking which was controlled by a thumb lever on my left handlebar regen charge and coming up to this but after lots of testing it only increased the range by about 3.5% and get the power on oh yeah it's got plenty of torque I ran this same set up to the following eight months and rode around 1500 miles with minimal issues other than replacing the belt once in fact I ended up replacing the tires and brake pads more often which led me to eventually upgrade the bike which required a whole new motor mount design and to do this I imported photos from multiple camera angles into my CAD software to produce a 3d model of the bike and design this bracket where the motor could be mounted behind the seat post and cut a prototype from plywood thinking difficult part of design the rear pulley as there was very little space between the wheel spokes and the brake caliper the plan was to mount the pulley to the brake disc as this was a pretty solid mounting point and then Ben some aluminium arms to an angle where they would just miss the brake caliper which was a very tight fit but work nonetheless then with a total of six spokes and a 3d printed toothed pulley it was time to work on the motor mount again which I realized needed a full redesign as I wasn't comfortable with this long arm potentially twisting into the rear will this new design utilized the water bottle mounting bolts and a clamp around the seat post at the rear which kept the motor protected inside of the frame but there was a problem the pedals hit the motor so I cut the end off and also mounted the belts and pulleys which as you can see there are two belts instead of just one this is to gain a larger pulley ratio between the motor and rear wheel where this belt produces a two-to-one step down and the larger belt produces a 37 to 4 step down meaning a total motor to wheel ratio of 37 to 2 or 18.5 to 1 but don't tell my math teacher this produced so much torque at the rear wheel that the pulley exploded instantly upon testing due to a weak design so I beefed up the spoke mounting holes and it held up a lot better but then I was having motor issues it seemed it wasn't possible to run the motor so close to the aluminium mount and yes aluminium isn't magnetic but if I drop this magnet down this aluminium tube you can see there's clearly some resistance I won't go into detail how it works but it was causing so much resistance on the motor that the motor lost sync with the speed controller and for a short period tried spinning the wrong way causing the Bell to skip and make that horrible noise so I had to widen the slot a little also the shaft was slipping in the motor due to my genius idea of cutting the end off so I had to make this plate to hold it in place and then 3d printed a cover for the motor and the bike was ready for a test ride and this was the last electric bike video I uploaded to YouTube but a lot has changed since then the dual pulley setup produce a lot of noise and resistance which reduced the efficiency and range so I flipped the most around I made a new mount which connected the motor output directly to the main drive belt and completely redesigned the large rear pulley to be manufactured from a single piece of aluminium which removed the need for the singular spokes and were spaced away from the brake using a few aluminium discs I also programmed an Arduino board together serial data from the speed controller and display all the important information on an LCD screen if you own a vest and want to make a similar display I'll post a link in the description for more info and this was a final design for the next year and a half when I decided to upgrade the motor the diameter of this new motor is 25% larger than the previous motor and it's got 42 magnets instead of 14 which I had no idea if it would improve the performance but it was worth a try the only problem is this motor lacked an output shaft long enough to mount a pulley as it's designed for mounting propellers too so I had to make my own shaft which would bolt to the motor housing passed through all the bearings and attached to a pulley like so this could then be bolted to the new aluminium motor mount with the other mount plate being cut from three millimeter carbon fiber to avoid the magnetic motor issues again and this fit nicely inside of the frame but spawn testing there was a noticeable vibration coming from the motor this was due to my amateur lathe turning skills where I machined the shafts slightly too small and there was playing the bearings so this is my work around a 12 millimeter shoulder bolt these boats have a shaft section which is machined perfectly to fit within bearings but to turn it into a usable motor shaft I filed down the head to lock into an aluminium bracket that I cut on my CNC router I then sprayed it black and bolted it to the motor and also cut me threaded section off then all I had to do was replace the bearings in the motor for 12 millimeter inside diameter rather than 15 millimeter and now I have a motor shaft with zero at play to complement the new motor I decided to build a new battery pack using these cells to do this I had to cycle charge every cell to measure their capacity which took just over a week entering all the values into a website called second life storage will calculate which cells should be put into parallel groups and I could then spot well the negative of one cell to the positive of a cell from another group until I had six pairs and I had to repeat this to make a pack of six in series and 6 in parallel then I added some power wise and a balanced lead to keep each cell balanced I choose not to run a battery management system on my electric bikes as I prefer to keep the batteries as small and simple as possible and I use my charger to manage the cell balancing so that's a 22 volt 24 amp hour lithium-ion battery pack and I need another one of them to white in series for 44 volts but it requires a different cell layout he's a slow-mo video of the spot welder at 800 frames per second it shouldn't always spark like that as I held the contacts at an angle which looks pretty cool but it also destroys the welding tips this new layout battery pack was the same 22 volts 24 amp hours but was slightly angled to miss the frame which when sealed in heat shrink was a very snug fit and then 3d printed a guard to stuck out the same distance as a motor pulley to prevent my leg touching it and this guard had holds through to the motor to help with cooling on the other side of the frame almost the whole motor was covered to prevent dirt and water from entering but they kept some slots on the rear side for air flow which seems to prevent oncoming mud from entering the only issue is air flow carries dust and since the manufacturer of the motor design at Fort remarkable cooling performance it also sucks up a lot of dust so I plan to build a dust filter for the in their holes using some open cell foam in the future so would I recommend you build an electric bike like mine the 3.5 kilowatt motor performance is great allowing it to accelerate to 30 miles an hour in a few seconds the range is decent with about 30 hours of fun riding and even more if cruising but if you just want performance hub motors are the best option this is a 3 kilowatt hub motor and it's super quiet when running of s6 as well as having better acceleration it is quite a bit heavier at 9.3 kilograms considering my whole setup including the battery weighs just 7 points but the hub motors will fit into pretty much any bike frame whereas my needs a very specific design to fit one big advantage of mine is it can be converted back to a regular bike in about a minute or two by simply removing the battery and taking the belt off leaving the motor and wires behind which adds about two and a half kilograms of weight I know that many of you who follow my channel are engineers and most likely wants to build an electric bike from scratch and the most common question I get asked is how do you choose a correct motor these hobby-grade brushless motors have two important specifications the size of the motor is usually labeled as a four-digit number for example this is a 63 seventy-four turnigy motor and I wouldn't recommend going much smaller than this for an electric bike the second specification and probably the most important is the kv rating which isn't a measurement of kilovolt but instead the velocity constant and it essentially relates to how fast the motor will spin depending on the voltage of battery that you have for example powering this 149 kV motor with a 50 volt battery will rotate at roughly seven and a half thousand rpm ideally for this size of motor you want to be within 100 to 200 kV for an electric bike the next thing to calculate is the motor to wheel ratio whether you choose to use a belt chain or geared system there needs to be a ratio between the two throughout all my ebike developments I've realized one golden rule to getting this right and that's this calculation the kv rating multiplied by the motor to wheel ratio needs to be approximately 10 for example my first electric bike had a 149 kV motor with a 14 2012 tooth wheel pulley which outputs a number of 16.7 which is way too high and is the reason it lacked in talk my version 3 II bike had a value of ten point four which was pretty much perfect and my latest version has a value of eleven point two which is still fine as the motor is quite a bit larger and can handle the talk interestingly enough the three kilowatt hub motor is 8.9 kV which when plugged into the equation with a one to one ratio gives a value of eight point nine so essentially this equation converts the smaller motor rpm rating to a hub motor equivalent so I hope it's also vinter some of you and hopefully inspire some of you to try and build your own electric bike if you enjoyed the video if you go if you can leave a thumbs up down below if you're new to my channel I want to see other crazy projects click subscribe down below a massive thanks to all of my supporters over on patreon comm for making these projects possible thanks once again for watching and I'll see in the next video goodbye Oh

Channel: Tom Stanton

Views: 4,062,035

Rating: 4.9131837 out of 5

Keywords: ebike, electric bike, DIY, homemade, brushless motor, 3D printed, 3d printer, 3d print, CNC, aluminium, carbon fibre, motor, battery, lithium ion, tesla, spot weld, range, electric vehicle, engineering, mechanical, electrical, electronics, lathe, bike, bicycle, motorbike, powerful, 3kw, 3000w, belt drive, how to

Id: 1pm1RtCuE3A

Length: 14min 7sec (847 seconds)

Published: Tue Apr 21 2020

Reddit Comments

[u/ParlourK]

Love stanton, hes not popped up in my feed for a long while.

Who woulda thought zip tying a gear to the spokes would last lol.

[u/snippysnapper23]

That belt drive is sick! Wish my haibike had one

[u/marsrover001]

There's a point where buying something off the shelf can just do a better job entirely than anything you make.

Hundreds of hours of research and fabrication shown in this video, all that could be replaced by one bbshd.

I like the building part, but I like the riding part more.

[u/endoplasmikretikulum]

a bike has got an ebike system without PAS, is not ebike. ebike system should not completely replace the human, only assisting human. The bicycle used without pressing the pedal is a scooter.