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How to Build a Fast Electric Car for School

Electronics and speed go hand in hand, and they have since the first electric cars began trouncing the horse-drawn carriages of their day. At first blush, electric motors seem like the perfect powertrain choice; they're small, light, produce massive low-end torque, don't require transmissions and have only one moving part. It's the battery and power control technology that lets the system down. If you want to build your own electric speed machine, the solution is to simply start with an existing car and bypass the stock batteries to power the motor with a supercharged battery pack of your own.

Things You'll Need

1/12 scale remote controlled car requiring 4 to 6 AA batteries
Screwdrivers
Wire cutter/stripper
3-volt triggered universal relay
9-volt battery connectors with leads, at least 2
18 gauge wire, black and red
Soldering iron
Flux core lead solder
Electrical tape

Instructions

- 1
  Remove the screws that secure the car's body to the chassis. You can usually find these screws around the bottom of the car's chassis. Pull the body off of the chassis.
- 2
  Locate the main electric drive motor between the rear wheels. Identify the power wires; there should be a black one and a red one. The red one is the positive wire and the black is the negative.
- 3
  Identify the motor. Store bought R/C cars will generally have either a 130 series or 180 series motor. The 180 series is more powerful and uses a round case. The 130 series' case is squared off on the top and the bottom.
- 4
  Use your soldering iron to melt the solder that secures the wires to the motor and pull the wires free. Solder 3-inch extensions to your motor power wires, and wrap the solder joint with electrical tape to prevent shorting.
- 5
  Identify the terminals on your relay. You'll see one labeled "ground." The one opposite that is the signal-in terminal. The terminal clockwise from that is main power input, and the one opposite the input is the main power output.
- 6
  Solder the black wire (formerly connected to your motor) to the ground terminal on the relay, and solder the red wire (also formerly connected to the motor) to the terminal opposite that. Cover both terminals with electrical tape.
- 7
  Solder the red lead from one battery connector to the black lead from the other.
- 8
  Solder the remaining red wire from your battery connector to the power-in terminal on your relay. Solder another wire to connect the power-out relay terminal to the motor terminal where the original red was soldered.
- 9
  Solder the battery pack's black wire to the motor terminal where the black wire was attached.
- 10
  Solder a red wire lead from your relay's output terminal to the the motor where the red wire was attached. Wrap all of your solder connections with electrical tape.
- 11
  Wrap all of your solder joints with electrical tape, and snap a pair of batteries onto you 9-volt battery connectors. Secure the batteries to the chassis as close to the rear axle as possible; use electrical tape to tie them down. If possible, place the batteries behind the axle for maximum traction.

Toy Vehicles