Constant Speed Vehicle

I bought these for my high school physics students to use at the AP level. I purchased four cars, I wish the documentation was better written. Particularly with battery diagrams. The battery compartment is confusing, the plus and minus terminal labels look as if the batteries should be connected in series but this is not consistent with the direction the springs are set up in. The springs which normally connect to the negative terminal on a battery look as though they are meant to be installed in parallel. Very confusing for me and my students. One of the four carts had a short circuit. I installed one battery, flipped the switch on and the wheels did spin but worse, the battery got hot. Hot battery indicates a short in the circuit. The battery covers are flimsy, sometimes they pop off and they are not supplied with screws to secure them despite having screw holes. Because of the confusion with the batteries one of the working cars caused some batteries to overheat and melt. It now can only be used with one battery as the heat caused deformation of the spring. I had high hopes for this product but it did not meet my expectations as a teacher of physics. I highly recommend better quality controls as the electrical issue could injure students. I will not be using this product in my lab again.

On/off switch is a bit Flemsy. Not confident this will last.

Two cars of the five I ordered were broken. One the on/off switch didn’t work and the second the bottom portion with the motor wasn’t fully attached.