need relay help


I am designing a power wheels car that will be button operated using an arduino uno. I have my code working for my push buttons however I am running into a problem powering the car. I obviously cant run the car through the arduino as the power needed to run the motor is more than the arduino can safely put out. So my solution is to hook up the buttons to a relay with the buttons being powered from the 5v output on the arduino. I am however having trouble finding a relay that will work and was wondering if anyone has any suggestions. The cars battery and the circuit that would be activated by this relay would be 6v. Any suggestions would be extremely helpful as I want to make sure I am buying the right thing. Other than this the rest of my circuit is working.

Thank you!

Well, you could get any number of things to power your motors. Just look up "Arduino motor driver shield" and choose one of those. If you are using only one or two motors, I would suggest a L298 Dual H-Bridge motor driver. If you are using three or four motors, then I would go with a L2930 Four-motor driver instead. You can find any of these on Amazon and Google for relatively good prices, usually about 10-20 bucks each.

I would definitely research the power draw of your motors though, so you don't get a driver with too little an amperage tolerance. Most motor drivers will peak at 1 amp, and overheat if used for too long at their maximum capacity. If you are looking for a higher power sort of controller, look into a hobby grade ESC unit. Although they are more expensive, they are definitely worth it.

If those aren't enough, just use the mechanical relays typically found in cars. They're a pain to wire, but once you get them working, well, you got yourself an industrial grade H-bridge motor driver.

Good luck finding the proper unit! Also, a little tip: power your Arduino and your motor controllers separately. It works better that way. With a lot less problems, I might add.

  • Dangerously Explosive

You need to figure out max. current the motor will draw and find a relay or switching semiconductor that will work for you that has a coil voltage/coil current rating that the arduino can meet.

So my solution is to hook up the buttons to a relay with the buttons being powered from the 5v output on the arduino.

If you hook up buttons to a relay, where does the Arduino fit in?

Further, be aware that 6V is the absolute minimum to power the Uno via the barrel or Vin; you might be better of using 7V or higher.