[MOD] BuWizz 4.0, the 22 volt version

[Marxpek]

Hello all, it's me again with yet another silly video.

I used the old 9v system lead plates and a 9v wire and 3 pf extension wires to connect 2 BuWizz up in series, making them produce over 22 volt on one of the PF connectors

Like the video tells you: it is a bad idea, so i did it anyway:

Of course this is just simply overvolting your motors, potentially damaging them (over time).

This is a pretty dangerous idea; in some spots your are just 1 stud of from shorting the sytem and probably melting the wires, or worse, killing the BuWizz, I will not explain how i made the circuit, if you are not confident that you can create it yourself; it is probably a bad idea to do so.

The difference is as expected, no torque lost and double the speed, but electrically things change as well. The BuWizz in series should still have their 5A (surge) protection, this will not double when in series, however the current drawn from by the motor should theoretically double when you double the voltage, so there are limitations to how much the system can deliver, double the buwizz, half the motors.. there is a good chance a buggy motor will melt the 9V wire, worth a shot i guess.

It also came to my mind i might not need 2 buwizz for this, but it felt wrong to hook up 1 buwizz in series from 2 ports, might work but somehow i didn't dare to try it, yet..

Do not try this at home unless you are absolutely certain you understand the circuit, also making a mistake in the app can cost you dearly (reversing polarity on 1 buwizz would be bad..) and you should be willing to burn up your motors, although i have had a few people tell me Lego motors can withstand 24v with ease, i am a bit sceptical  myself tho. There is still the built in "thermistor" on the pf motors (except the m) that cuts the circuit in the motor for a while when overheating, but that is made for overcurrent, not for overvoltage, so i am unsure, I have not damaged any parts myself, having a multimeter at hand is a must, check, check, doublecheck..

now what could we do with this?... ;)

 

Edited January 16, 2021 by Marxpek

[2GodBDGlory]

That's fun!

It would be interesting to know how long motors can run at such high voltage!

I wonder what purists would think of doing a similar thing with only official Lego power supplies. It would only use Lego, though certainly not in a way Lego expects it to be used!

[pdw]

From watching your video, I don't think it's the voltage that's going to kill your Lego, it's that wall :-)

Quote

There is still the built in "thermistor" on the pf motors (except the m)

I'm curious about this.  I've not taken a PF M motor apart myself, but the images and videos I've seen all seem to show a thermistor.  Meanwhile I've seen various references to M motors having a large filter capacitor, which I've not seen.

[dr_spock]

PF M-motor has this soldered to the motor terminals.

 

[pdw]

That looks like the thing I've seen, wired in series with the motor, not across the terminals, and positioned so that it's in contact with the motor so I assume it's a thermistor.