Convert Acton Blink S2 Electric Skateboard Into an Inefficient, Heavy and Loud Electro-mechanical Lamp

The title says it all. The end result of this project is practically useless, but it can be a great opportunity to study the basics of electronic circuits.

Find an old electric skateboard in the garbage. Make sure that the wheels spin freely. Make sure that both the remote and the charger were lost long time ago. Make sure that there is no way to resurrect it in its original form and shape.

In order to convert it to an electro-mechanical lamp you'll need the following components:

1. 2 x perfboard
2. Resistors: 3 x 5Ω 2W, 1 x 100Ω 2W, 2 x 10kΩ 0.25W
3. 2 x 12mm toggle switch with LED
4. 2 x 3.6-30V buck-boost DC-DC converters
5. 2 x IRF9Z34 MOSFETs
6. 2 x SKBPC5016 3-phase rectifier bridge AC-DC converter
7. A bunch of electrical crimp terminals
8. 4 x 63V 4700uf capacitors
9. DC power sources for 5 and 24 volts
10. Thick double-sided adhesive tape
11. A tube of silicone sealant
12. Solder, wires, heat shrink tubes, double-sided tape

You'll also need the following tools:

1. Large screwdriver with torx bits
2. Small screwdriver with flat head
3. Pliers
4. Wire cutters
5. Snap-off blade knife
6. Multimeter
7. Soldering iron (and solder)
8. Crimper tool
9. Kitchen thermometer
10. Dyson V8 Absolute with motorized soft roller cleaner head

Disassemble the electronics compartment. Dispose the battery. It's big, old, and can be dangerous under certain conditions. You probably don't want to keep it at home, unless you know what you are doing.

The only preference I had when starting this project was that it should not involve a battery. This skateboard has integrated lights in front and back, as well as LED strips on the sides. With these things in mind, I came up with a silly idea of generating power for the lights by pushing the skateboard manually. One can say that this is a sort of reverse conversion from electric to manual skateboard.

Wheel hub motors produce electricity when you spin them. The amount of power they produce should be enough to keep all the lights on, at the expense of slightly increased ride resistance. All we need is to convert AC voltage to DC and keep it at a constant level.

The original ESC board produces unregulated DC voltage at the battery terminals when the wheels spin. This might have been a part of the recuperative braking mechanism. In theory, you can use the ESC as an AC-DC converter, which would drastically reduce the effort. However, it's a complex piece of electronics, and you probably don't want any surprises when riding your board down a hill. On top of that, one of the wheels had more resistance than the other, but only when it was connected to the ESC, which could be a sign of a short circuit. After some research I went with 3-phase bridge rectifiers, capacitors and buck-boost converters.

The casing has two round holes: one for the power switch and another for the charging port. We can use them to mount latching toggle switches for the lights. Speaking of the lights, the original design of this skateboard contained a dedicated circuit that was responsible for powering up and controlling all of them together. The circuit was managed by the ESC using two control wires, and it was likely expecting a constant voltage at the input. Unfortunately, I could not find a way to control the circuit as-is without the ESC, so I decided to replace it with a custom one.

The toggle switches are rated for 3-6 volts, and they have integrated LEDs, which should work comfortably in that range. Front and rear LED pairs are connected in a series. The white LEDs have a higher voltage rating than the red ones. If we re-wire the front white LEDs in parallel, we can power all front, rear and switch LEDs with a 5v line.

The side LED strips activate at 24v. That's too high for our toggle switches, so we'll need MOSFETs to turn them on and off using 5v control voltage. Speaking of MOSFETs, my original plan was to power the 5v LEDs directly via one of the toggle switches, and used MOSFET for the 24v line. Later on I decided to not stress the switch with relatively high current and use MOSFETs to control both power lines.

In this step, ChatGPT was extremely helpful. You can ask it all sorts of stupid questions, identify circuit board components from photos, conduct practical experiments with a multimeter by following its instructions, and discuss the general plan.

You can view the schematic on TinkerCad. Please be aware that simulation mode often hangs, most likely due to a high number of components in the circuit.

Set the buck boost converter output to 5 volts. Use a 5Ω resistor to measure voltage drop and forward current of front and rear LEDs, as well as LEDs in the toggle switches. This were the values I got:

1. Single front white LED:
2. Current: 180mA
3. Resistor voltage: 0.9v
4. LED voltage drop: 4.1v
5. Resistor power: 0.162w
6. Two rear red LEDs in series:
7. Current: 93mA
8. Resistor voltage: 0.465v
9. LEDs voltage drop: 4.535v
10. Resistor power: 0.043w
11. Toggle switch LEDs connected in parallel:
12. Current: 40mA
13. Resistor voltage: 0.2v
14. LED voltage drop: 4.8v
15. Resistor power: 0.008w

The front and rear LEDs are quite powerful, and the backs of their PCBs are coated with aluminum. It looks like they can easily handle hundreds of amps without overheating. This can be verified this with a kitchen thermometer. The toggle switches are rated 3-6v and up to 3A, and they have integrated resistors for the LEDs.

To test this setup I used two packs of 3 x AAA batteries for testing, which gave me 9 volts. Later on I switched to a DC power supply.

Set the second buck boost converter to 24 volts. Use a 100Ω resistor to measure the side LED strips. This were the values I got:

1. Single LED strip:
2. Current: 7.7mA (x2 for two strips?)
3. Resistor voltage: 0.77v
4. LED strip voltage drop: 23.3v
5. Resistor power: 0.018w
6. LED strip power: 0.18w

Upgrade the LED control board by adding MOSFETs for controlling the 5v and 24v power lines.

Connecting resistors in parallel reduces their resistance and increases their max power. Initially, I was going to use pairs of 0.25W resistors wired in parallel, but they were getting pretty hot, and I ended up replacing them with the ones rated for 2W.

Soldering MOSFETs was quite difficult due to heat dissipation. If your soldering iron has temperature control, it's probably a good idea to turn it up.

Connect hub motors to the inputs of 3-phase bridge rectifiers via the original ESC connectors. Solder capacitors to a perf board. Connect the outputs of the rectifiers to the inputs of the capacitors board. Connect the output of the capacitor board to the input of the buck-boost converter.

Crimp terminals allows for simple disassembly, but you don't have to use them.

Assemble all circuits and components together. Use double sided tape to mount the boards. If the board contacts touch the metal casing, you can use a thin plastic spacer cut out from a disposable food container.

Make sure your silicone sealant does not conduct electricity, and use it to fix all moving parts. Additionally, you can seal some obvious gaps in the casing to protect the electronics from dust and water.

It's been fun! Turning the lights on adds noticeable resistance to the ride. The board makes a funny noise. But hey, this was an educational project from the beginning, and I hope you've learned something by tagging along!

If you have any questions feel free to submit them in the comments 😊 If you have made something similar - please let me know!