Philo Posted October 15, 2013 Posted October 15, 2013 Hello all, I just updated my motors comparison page with measurements of the EV3 motors. As expected the EV3 large motor is very similar to NXT motor. EV3 medium motor delivers a power close to PFS medium motor. It provides more torque thanks to a higher down gearing (speed is 260 rpm vs. 405). Quote
JopieK Posted October 15, 2013 Posted October 15, 2013 we just saw it today at my school ;) B.t.w. why is the stalled torque lower for the EV3 large servo do you reckon? 50 N.cm for the NXT and 43 N.cm for the new one. In the lower table you say that normal torque is 17.3 N.cm for the new one versus 16.7 N.cm for the old one. Quote
Jim Posted October 15, 2013 Posted October 15, 2013 Thanks Philo. Nice work! Great to have the comparison page updated with the new motors. Quote
Philo Posted October 16, 2013 Author Posted October 16, 2013 B.t.w. why is the stalled torque lower for the EV3 large servo do you reckon? 50 N.cm for the NXT and 43 N.cm for the new one. In the lower table you say that normal torque is 17.3 N.cm for the new one versus 16.7 N.cm for the old one. Measure of stalled torque is very imprecise, and a 3.5% difference in "normal" torque is nothing considering the overall precision of measures - especially since the high torque of EV3/NXT motors stresses a lot my test setup. More significant is the low energy efficiency of EV3 motor compared to NXT, but I can't really find a reason. Poor lubrification in EV3 motor? Quote
DrJB Posted October 16, 2013 Posted October 16, 2013 Thank you Philo, commendable work. You mentioned poor lubrication, and here is something I noticed. My EV3 motors tend to be noisier than the NXT. I had suspected as well that improper lubrication might be the culprit ... Yet not willing to sacrifice one the motors and open it up yet. On the other hand, the choice of grease with plastic gears is very 'delicate' ... Quote
JopieK Posted October 16, 2013 Posted October 16, 2013 That is interesting indeed, one would hope, new version, better version, but alas ;) @DrJB: LEGO has some experience on the matter we would think wouldn't we?! Quote
TasV Posted October 16, 2013 Posted October 16, 2013 I'm impressed with the increase in torque in the EV3 motor, but she's power hungry!!! Quote
DrJB Posted October 16, 2013 Posted October 16, 2013 (edited) @DrJB: LEGO has some experience on the matter we would think wouldn't we?! Of course they do, but as always, any given design is a balancing act of various performances (balancing = compromises). I was by no means 'criticizing' TLG ... I was simply looking at it from 'my' area of expertise i.e. noise. I can tell you for sure that TLG motors are NOT optimized for noise. The latter is often perceived as an 'indicator' for good/bad product quality. I have done sound recordings (of EV3/NXT motors) and Fourier analysis ... and the spectra suggest it is the gears that are noisy (too much backlash), not the electrical motors. This, to me, is an indication of 'improper' gear design, but then again, this is a toy, not a high-tech commodity ... I'll stop here as we've ventured a bit off-topic. Edited October 16, 2013 by DrJB Quote
JopieK Posted October 16, 2013 Posted October 16, 2013 It is an interesting addition though!, maybe Phillipe could even incorporate sound measurements in his motor expose?! Quote
Philo Posted October 16, 2013 Author Posted October 16, 2013 (edited) It is an interesting addition though!, maybe Phillipe could even incorporate sound measurements in his motor expose?! Mmhhh... I am not well equipped for that kind of measurement... I noticed too the noise of EV3 motors, that's what lead me to thing that it could be a lubrification issue. But then I heavily tested only one motor, it could be a problem specific on this one... I have not tried yet to open the motors, but anyway it is not possible to open them fully without breaking the red hub (like the NXT motor). BTW, you can see a reverse-engineered schematics of EV3 motors internals here: http://bberry.perso.neuf.fr/swcaddb/Lego/CDEV3pack.htm Edited October 16, 2013 by Philo Quote
DrJB Posted October 17, 2013 Posted October 17, 2013 I'll try to find sometime and do this ... no promises though. Quote
lcaa Posted October 18, 2013 Posted October 18, 2013 Thanks for that comparison! Very useful! Tom Quote
ntale Posted February 16, 2015 Posted February 16, 2015 If I use 11.1V instead of 9V battery, will the EV3 motor blow up instantly. What is your experience? I want to do this for kids science project to increase the speed of the motors. What is the best to increase max motor RPM. Quote
Blakbird Posted February 16, 2015 Posted February 16, 2015 If I use 11.1V instead of 9V battery, will the EV3 motor blow up instantly. What is your experience? I want to do this for kids science project to increase the speed of the motors. What is the best to increase max motor RPM. No, motors don't blow up instantly from over-voltage. What they do is get hot and then eventually burn out. Running at 11.1V is going to spin faster but also draw more current for a given load. The correct way to get more speed out a motor is to gear it up mechanically. LEGO motors are very carefully quality tested for reliable capacity. Personally, I would not intentionally overload the motor or otherwise defeat those limits. Use gearing. Quote
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