I bought a small brushed (my guess) DC motor with integrated reduction gears off Banggood: here's the link to the product page: https://www.banggood.com/12V-DC-3RPM-High-Torque-Electric-Geared-Box-Motor-p-989186.html
Since it comes with no sort of technical data, aside from the rated rotational speed and voltage (3rpm at 12V with no load), I wanted to investigate more on it, so I measured the running current draw with no load, and the stall current by mechanically blocking the shaft and using a multimeter in "Amp mode". I'm a complete noob so I just followed this guy's tutorial: https://www.youtube.com/watch?v=gwFE-NkzR-k
Although I haven't really measured the rpm to check if they match the rated value (speed is not a concern), the motor works just fine, but what I got was:
- a no-load current so low it could not be detected by the multimeter (below 10mA)
- a stall current of approximately 40mA.
It would have seemed fair enough to my inexperienced eyes, since 12V*40mA=0.48W, it kind of made sense to me! But in that same tutorial I mentioned, as well as on a handful of other internet sources, I saw the value of the stall current ranging around 500mA for similar motors. Now I understand that "similar motors" is not really a valid definition, nor a good means of comparison, given that they can vary a lot in behavior even if they have, say, the same rated voltage, and also when I don't really have a datasheet as a reference to make such comparisons in the first place.
I just wanted to know if those numbers, especially the 40mA stall current, are plausible even to more expert eyes than mine. I also hope I was clear enough for you to express a judgement.
This is really all I have to give you, and I do not have any other multimeter to double-check these figures I am getting. Thanks everybody!