|Parts & Materials:|
So the first step is the design. I would not give you exact numbers because you will have to find it by your own. Take your child and measure them. Consider to measure following properties:
- legs length - this will determine the chassis length.
- arms length - this will determine how far from the seat the steering wheel should be.
- body size - this will determine the size of the whole car.
- kid weight - this will determine how strong the construction has to be and how big of batteries you should use.
OK. You have dimensions, so you can build the frame. I've used the pine wood for the frame, mainly because it is the light and flexible wood. Flexibility is important because my electric car won't have any dampers (only wheels with bicycle-like tires).
I also made more sensitive car parts from wood, but from stronger ones like oak. So the whole front suspension is from oak.
The car body can be made from plywood. It's cheap, easy to work with (only saw is required) and it is strong enough. I only recommend using 1" thicker wood for the sides of the car where those sides should be from more resistant material than plywood because they have to sustain getting in and out from the car.
Electronics isn't very complicated thing.
First you have to choose the engine. I've used 350W 24V DC engine with built-in gears reducing RPMs to about 600 RPM. It is enough to allow my son to drive with the speed of 9mph (15kmh).
The engine is controlled with the Chinese controller which you can easily buy on eBay. The controller is also connected with the ignition switch and with the gas pedal made from the Hallotron of an electric scooter (those parts are cheap and also easy to find in internet).
The power is transmitted to the rear wheel by the freewheel. It's a gear which doesn't roll during riding down the hill. It's important because it stops generating the back currents. Such currents could destroy the controller.
If you think all of that is a little bit tricky - don't worry. Just buy whole engine+gears+controller+gas pedal kits. There are such things on internet.
I've used two 12V 18Ah batteries (exactly same like in the real car). Those batteries aren't a great choice for continuous load but there are cheap. They provide energy enough to ride up to 6 hours.
You have to remember that wires and DC current will generate the voltage loss. Losses depend on wire length and diameter - shorter, wider wire will produce less voltage loss.
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