0
$\begingroup$

I have a small raspi controlled remote control car using regular drone motors such as these ones and tried using this 60w power supply unit that can be downregulated to 3v and connected everything using two drv8833 motor drivers. However, the spikes in power drainage generated from one motor alone seem to be enough to drain the entire amperage of the circuit, in spite of each motor only consuming 0,15a. Is there a reason for this?

It's possible that there is some additional resistance when the motors start up causing them to drain more than the specified 0,15a, I am not using any gears but the car itself is very light so I don't think the spike in amperage drainage justifies all the other motors completely stalling when the power source is said to provide 60W.

The current limit for the DRV8833 is 2A, I am using two of those modules with each having two motors connected to them.

Is there a good solution to this problem? I tried placing a 3.300uF 6.3V capacitor around the motor driver but am still having problems with only one of the motors actually starting up

Improve this question
$\endgroup$
4
  • $\begingroup$ Are your batteries dead? Just because your drivers can pump 60W doesn't mean your battery can. :EDIT: Wait just realized I think you mean the car is powered by the plug-in power supply. I don't know where you have the capacitor exactly, but I would put a large capacitor between the power supply leads to your vehicle. Some voltage regulators will have a short-circuit protection that can generate basically the behavior you're describing. $\endgroup$
    – Chuck ♦
    Aug 18, 2021 at 13:01
  • $\begingroup$ @Chuck do you have a schematic with a similar layout you can link to? $\endgroup$
    – Yes
    Aug 18, 2021 at 16:38
  • $\begingroup$ Here is a link to a Digikey article (no affiliation) on capacitors and voltage regulators. Figures 1 and 2 show a "Cout" output capacitor. That's what I'm referring to. If you don't have one, add one, if you have one, get a bigger one. A few things to point out: 1)the power supply you linked does 60W at 12V; you're running it at 3V, where it outputs 15W. Still a lot, but 2)your motors might not generate enough torque to move a vehicle. $\endgroup$
    – Chuck ♦
    Aug 19, 2021 at 5:53
  • $\begingroup$ Two AA batteries in series would get you to 3V. This is probably the easiest way to test if your problem is the power supply or the motor - no capacitors required. If the (fresh! fully charged!) batteries can't get the motor to turn then you're exceeding the stall torque of the motor and you'll burn them up if you keep trying to dump current into them. Especially for drone motors - they're designed to have lots of airflow at their peak power consumption. $\endgroup$
    – Chuck ♦
    Aug 19, 2021 at 5:56

0

Reset to default

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Browse other questions tagged or ask your own question.