With the need for transportation along with the increase in gas prices, individuals are now seeking more efficient ways to get around. The only issue with these alternatives, however, is high cost and inaccessibility to the public. In this tutorial, we will be showing you how to build your own electric skateboard for just $300.
Hub Motors: For this build, instead of using the pulley system we use dual drive hub motors; mainly for simplicity (the pulley system requires more moving parts and mounting hardware than the hub motors). The hub motors used are rated for 600W, 90mm in diameter, and come together with the motors and wheels on trucks. The package also came with the non-motorized wheels in the front (also on trucks) which makes mounting this to any skateboard amazingly easy!
ESC: Now that we have our motors we need a way to control them therefore, we got an ESC (Electronic Speed Control). The ESC used in this project is rated for 36V and 12A – 432W. This is not enough power to fully utilize the hub motors however, it is more than enough for this application. The ESC has the red and black wires connected to an XT60 connector for our battery pack, a large button to turn the board on/off, six wires to connect to the motors, and remote control. For anyone wondering why there are six wires for the two motors (three for each), this is because the motors use three-phase power instead of traditional DC motors which only use two wires (one for live and one for neutral).
The ESC turns the DC voltage from our battery into a three-phase signal and controls the motor speed by changing the output frequency. When selecting an ESC, it is important to make sure the voltage matches the motors rated input voltage. The ESC also came with a remote that can be charged using a micro USB charger, a throttle which you can push to accelerate and pull to stop, a high, medium and low setting, a reverse setting, and battery life indicator lights.
Battery: Initially, the idea was to build the battery pack from scratch however, after further research it seemed more worthwhile to buy a battery pack that also came with the corresponding charger. We purchased a 36V battery pack which consists of twenty 18650 Li-Ion batteries (10 in series and 2 in parallel). The fully charged voltage of a single 18650 cell is 4.2V, therefore, the fully charged voltage of our battery pack (considering it is 10 in series) will be 42V which is why the pack came with a 42V, 2A charger. If we wanted to calculate an approximate charging speed for our battery pack, we can take the capacity of the pack (5.2Ah) and divide that by our charging current (2A) for a charging time of 2.6 hours (only theoretical).
When choosing a battery pack, you want to ensure that the voltage is compatible with the ESC and that the battery pack can handle the maximum current draw from the ESC. To do this, we use the formula P = V x I. We can take the established 432W from our ESC and divide that by the ESC voltage which is 36V to get a draw of 12A. If we wanted to ensure that it can meet the specs of the motors, we will take 600W / 36V to get 16.67A.
Skateboard: We can leave this up to the builder. Any type of skateboard should work from penny board to longboard, however, in this build, we used a penny board because we wanted something nice and compact. The only downside to a penny board is that it is less stable than the longer boards.
First off, our first problem for the build was that the connectors for the ESC and battery were not the same. To combat this, we replaced both with male and female bullet connectors (because it was the only ones we had on hand) – male on the ESC and females on the battery pack.
CAUTION: The battery pack is always live – try not to short the +ve and –ve wires.
Next, we wanted to take some sheet metal and create an enclosure for the ESC and brackets to mount the battery back.
Once the metal was cut and bent into the desired shapes, the parts that will be exposed were spray painted black for a nicer finish (two coats applied).
Once all the paint was dry, we mounted all the parts and brackets to the board with a rubber insulator between the board and the metal for some shock absorption. After all the parts were mounted to the board and all the wires were connected, our build was finally complete!
The First Ride:
The first ride on this board did not go as expected. Since I rarely ride skateboards in general, I accidentally mounted the trucks backward which inverted the steering of the board making it very difficult to control. After realizing what was wrong, I reversed the trucks and switched the motor wires so that they would spin in the right direction and the board was much more stable.
Based on the product description on aliexpress, the max speed of the board was calculated by taking the rated rpm (1500-2500rpm) and wheel size (90mm) and use this to get a speed in km/h.
Pi * d = Pi * 0.09m = 0.283m
0.283m * 1500rpm = 424.5mpm 0.283m * 2500rpm = 707.5mpm
424.5mpm * 60min / 1000 = 25.47km/h 707.5mpm * 60min / 1000 = 42.45km/h
From these calculations, we can see that our max speed should be around 25.47-42.45km/h. Due to a number a factors, an accurate estimated range for the board cannot be obtained easily.
After riding the board and tracking the speed and distance of the board using an app, we have concluded that the max speed is close to 35km/h. We do suspect that the board can go faster however, we are too scared to find out the true max speed on the board. As for the range, on one full charge, we have been able to travel a total of 10km until the battery finally died and a full charge will take 2.5-3 hours.
Electric modes of transportation are rapidly growing in popularity. Unfortunately, they are not decreasing in price making it inaccessible to the majority of the public. In this build, we took an ordinary skateboard and transformed it into an electric skateboard with some very good specs for only $300. Another benefit of this build is that the parts are easily interchangeable with any board and replacement parts are easily accessible. This board is insanely fun to ride and we highly recommend trying this build out for yourself; just remember to wear some protective gear when riding.
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