Calling All Science Guys! Why Does This Happen?

[Max-U52]

Just kind of stumbled across this, and it made me wonder. Can anyone explain why this happens?

phpBB [video]

My best guess is that it's kind of like KERS in Formula One race cars.

[Raminator]

You hit the nail on the head Gary, when you're applying torque to the motor it's acting like a generator. There's actually no functional difference between an electric motor and a generator, it's just a case of where the energy is being put in. Lots of electric and hybrid cars use it for regenerative braking, so that you can recharge the batteries while you're not under power.

By turning the first motor, you're moving the rotor's coil past the permanent magnets and since there's a magnetic flux that creates an electric current. Since the two motors are hooked up together, that electric current can then turn the second motor (the electric current through the coil causes it to act like an electromagnet and repels the permanent magnet, causing motion). Like you said, pretty cool. What impresses me is that you're getting enough current out of the first motor to turn the second motor at about the same speed, they must be pretty damn powerful and efficient.

[dgsselkirk]

Flux capacitor!

[dgsselkirk]

That was after he went to the future and came back. Originally powered nuclear from the plutonium stolen that was supposed to go to the Libyans. Wasn't the power source I was referring to, simply the magic of the magnetic field generated to rotate the unpowered motor hence the word "flux" and the "capacity" to generate secondary power similar to flux capacitor. Of course if you hooked up a large enough power source to the tank to produce the necessary 1.21 gigawatts and speed the tank to 88 mph then Gary would have a time machine...

flux capacitor formula.jpg (78.92 KiB) Viewed 1549 times

[jarndice]

Looks like Christies Suspension system is about to make a comeback with its 50mph + ability ,
Will that be with or without tracks ?
Shaun.

[Raminator]

If my calculations are correct, when this baby hits 88 millimetres... you're gonna see some serious shit.

[wibblywobbly]

The same happens on 3D printers. If the printer is switched off and I slide the print bed around (which is connected to a toothed belt and a stepper motor) then the LCD screen will power up.

[Saracen]

This is related to the hotly debated topic of regen braking and LiPos.

When you tank is all wired up, instead of that current going to the other motor, it's going to go back into the LiPo via the Sabertooth controller.
If the LiPo was fully charged to begin with, you run the risk of over-charging the LiPo.

That's the basics, but there's a lot of give/take on various forums as to whether there is enough regen effect for it to ever affect the LiPos.

It would be interesting to connect a DVM to the motor leads and see what sort of voltage you can generate by turning the sprocket at different speeds.
If you can get more than 25V, you risk putting too much voltage back into the LiPos. Allegedly

Adrian.