Trying to build a small motor driven car, problems with motors and wheels

[paulsutton]

I am trying to build a small motor driven vehicle,  this is toy size.   I have a polycarbonate sheet and 4 motors,  and 4 plastic wheels (but also have other wheel, so can interchange them.

I have wired this up so far so that 2 of the wheels are wired up to a battery,  the other 2 wheels are just attached to motors,  my main issue regardless of how I do things, is that a motor plus wheel spins if held up,  as soon as I put down on a flat surface,  the motor + wheel stops turning.

I am not an engineer, so not really sure what to do here.

 

Thanks

 

Paul

[swansont]

5 minutes ago, paulsutton said:

I have wired this up so far so that 2 of the wheels are wired up to a battery,  the other 2 wheels are just attached to motors,  my main issue regardless of how I do things, is that a motor plus wheel spins if held up,  as soon as I put down on a flat surface,  the motor + wheel stops turning.

Motors don’t always spin freely. The unconnected motors may be offering too much resistance for the car to move. Does the car roll very far if you just push it (no batteries)?

[Externet]

The battery is too weak for the motors demand.   The motors are too weak for the motion demand.   The motors are too demanding for the battery capability.  The connecting wiring is not soldered presenting resistance to electricity flow.   The gearing does not match the needed torque.  The motors that are not energized are presenting braking effect to the others.  One or more of the above.    Check if the car rolls smooth by hand when not energized.  Try energizing only one wheeled motor instead  and come back with observations.

[paulsutton]

Hi

Thanks for these suggestions, I will do as suggested.

 

Paul

[paulsutton]

There is definitely a power issue.  Using 2x cheap batteries and 2x Duracell makes a huge difference.

I have wired up 2 motors, so that a battery pack can power 2 motors,   then just need to do the same the other side.

Paul

 

 

[paulsutton]

Update, I managed to get this working nicely using 2x AA batteries powering 2 motors at the front and the same for the other 2 motors at the back,  bigger wheels also help.

I am now looking to rebuild, motors will be glued on, with hot glue, rather than with sticky pads, gives a chance to do a quick re-design to make the wiring better.

Thanks for the help / advice on this, really helpful.

Paul

[pzkpfw]

Can you use pipeclamps and bolts?

Glue is pretty one-way.

(Though drilling polycarbonate sheet for bolt holes can be tricky.)

[hoanghuan89]

I think you need a circuit to control motor speed.