Hi All,
I have made a battery powered go kart for my kids
it consists of a unbranded controller (unidirectional), 2 DC motors (traxxis - RC motors), and a hall effect foot throttle. I have a simple dpdt relay/switch to activate the forward and reverse.
i am now trying to work out if i can connect another hall effect pedal to act as a brake pedal. Could this be possible? if so, i need all the help i can get! im guessing i need a separate relay and pedal, although have no idea how to wire it all up.

i have no experience in this field just trying to find things online although i cant find anything for the above
would greatly appreciate any feedback and support in pointing me in the right direction.

thanks
Sam

 

I am assuming you want to use the motors for braking. This is not trivial and will require somehow dissipating a lot of power.

You can do resistive braking, turning the momentum into heat, or regenerative braking where the batteries are charged by the braking force.

In any case, it requires some pretty heavy duty components if you want it to be proportional, as your hall effect comment suggests.

If you want just a simple brakes on/off, you don't need, or even want, the hall effect sensor, just a switch that can operate something like a relay which removes power on the motors and puts the resistor in place. There are several considerations (back EMF, current handling, relay contact arcing) that you need to address.

And, such a simple system may not be very drivable, I really don't know how it would behave from the driver's point of view. It might be fine, but if might be quite abrupt, and it would have no holding power so the car would stop, but then roll.

 

there is too much there for me to process - wow. i like the charging the battery though!
the only thing that i know for sure is i dont want the abrupt stopping as this will put too much pressure on the gearbox (plastic gears) and could break them as the dc motors are spinning at 31,000rpm. Well i think that will happen???

back EMF, not exactly sure what that means although i have a capacitor straight off the motor to reduce the noise - is that what you mean?
the contact arcing, can that happen with a hall effect throttle or are you referring to the on/off pedals? i have heard of on/off throttles arcing and staying on and kids hitting walls etc. this is why i would like to set it up right although at the same time teach my kids how to drive sensibly

 

there is too much there for me to process - wow. i like the charging the battery though!
the only thing that i know for sure is i dont want the abrupt stopping as this will put too much pressure on the gearbox (plastic gears) and could break them as the dc motors are spinning at 31,000rpm. Well i think that will happen???

back EMF, not exactly sure what that means although i have a capacitor straight off the motor to reduce the noise - is that what you mean?
the contact arcing, can that happen with a hall effect throttle or are you referring to the on/off pedals? i have heard of on/off throttles arcing and staying on and kids hitting walls etc. this is why i would like to set it up right although at the same time teach my kids how to drive sensibly

You'll find that a lot of people don't call a motor a "motor". They call it a "machine". That's because it's also a generator.

When you want your car to brake, you remove the power supply to the motor. At this point, the motor stops accelerating the car and it starts generating instead. To get the car to stop, you need to turn it's kinetic energy into something else. The most common way is to put a resistor across your motor. Now the momentum of the car keeps the motor spinning, which is now acting like a generator which pushes current through the resistor causing it to heat up and dissipate the car's kinetic energy as heat.

A more complicated solution is to take the power generated by the motor and "push" it back into the batteries. This is called "regenerative braking". Googling "braking resistor" and/or "regenerative braking" should throw up lots of information.