PFS-Large motor now in motors comparison page

[Philo]

Hello all,

I just updated my motors comparison page with measurements of the new Power Function Large motor.

Also includes a few new synthesis charts:

Enjoy!

[DLuders]

Wow -- this is very timely! Your website has been (and continues to be) the benchmark by which Lego 9V motors are measured! :thumbup: Merci boucoup!

Edited July 7, 2012 by DLuders

[DLuders]

@ Philo: If you have time, could you create a new graph for the PF L-motor (similar to the one you made below for the PF M-motor)? I'm curious to see the difference in available Mechanical Power by using six 1.5V Alkaline batteries (9V) vs. six 1.2V rechargeable batteries (7.2V) for the new PF L-motor. There have been SOME recent videos of the new 9398 4x4 Crawler where the L-motors seem to be lacking power (possibly from using rechargeable batteries)....

[Philo]

Yes, that's something I intend to do. But I'd like to put my hands first on a V2 IR receiver to make at the same time a comparison of the receivers (Got only the motors so far...)

[Zerobricks]

There must be a mistake in the table PF L table, showing bigger mechanical power than electrical?

Edited July 7, 2012 by Zblj

[Conchas]

Great work as usual Philo!!

I'm also happy to see the values I've provided earlier are quite close to your measurements (380-400rpm and 110mA no load current).

The stalled current is the one I had most difficulty because I never observed a steady value. Started at something like 1500mA then continuously decreasing very fast (guess there is here a thermistor doing its work).

It is a pity we didn't get a motor with more torque out-of-the-box, so we need to gear it down as Allanp likes so much.

[DLuders]

From Philo's excellent "LEGO® 9V Technic Motors compared characteristics" webpage, here are some interesting comparisons between the three most popular Lego Power Functions motors:

Let's use the Power Functions (PF) Medium motor as a benchmark:

WEIGHT

M-Motor: 31 grams (g)

L-Motor: 42g (35% heavier)

XL Motor: 69g (223% heavier)

NO-LOAD ROTATION SPEED

M-Motor: 405 revolutions per minute (rpm)

L-Motor: 390 rpm (96% as fast)

XL Motor: 220 rpm (54% as fast)

NO-LOAD CURRENT

M-Motor: 65 milliAmps (mA)

L-Motor: 120 mA (85% more)

XL Motor: 80 mA (only 23% more)

STALLED TORQUE

M-Motor: 11 Newton-centimeters (N.cm)

L-Motor: 18 N.cm (64% more)

XL Motor: 40 N.cm (364% more)

STALLED CURRENT

M-Motor: 0.85 Ampere

L-Motor: 1.3 Amps (53% more)

XL Motor: 1.8 Amps (212% more)

Edited July 7, 2012 by DLuders

[timslegos]

Great information Philo! Thanks for taking all the measurements.

tim

[Philo]

There must be a mistake in the table PF L table, showing bigger mechanical power than electrical?

Thanks for spotting! figures for electrical power were those of e-Motor... now corrected.

[DLuders]

Thanks, Philo! From your PF L-Motor table, it seems that AFOLs using Rechargeable batteries (7.2V total) or the PF Rechargeable Battery Box (7.4V output) may be sacrificing the greater "Mechanical Power" offered by new Alkaline batteries (9V total):

VOLTAGE / MECHANICAL POWER

7.5 V / 1.38 Watts

9 V / 1.85 Watts (34% more)

Watts = Volts x Amperes. The more VOLTS one has, the greater the WATTS ("the rate of energy conversion or transfer").

Edited July 7, 2012 by DLuders

[allanp]

Thankyou for this Philo. There is one bit I don't get tho. In the tables, the RC buggy motor seems to give the most mechanical power at 9v, whereas the synthesis chart shows the XL motor giving the most power.

[Philo]

Thanks, Philo! From your PF L-Motor table, it seems that AFOLs using Rechargeable batteries (7.2V total) or the PF Rechargeable Battery Box (7.4V output) may be sacrificing the greater "Mechanical Power" offered by new Alkaline batteries (9V total):

VOLTAGE / MECHANICAL POWER

7.5 V / 1.38 Watts

9 V / 1.85 Watts (34% more)

Yes! Actually the situation is even a bit worse when using an IR-receiver. The current in the motor for a given torque depends little on voltage, so it is the same at 7.2V or at 9V. As the dropout voltage of the motor driver depends on the current, it is also the same at 7.2V or 9V... so it has more effect at lower voltage! That's why I'd like to make extensive comparison between IR receivers, since v2 is supposed to have a lower dropout (and probably higher current rating)

[Philo]

An error in values for 5292 motor in synthesis charts was found by DLuders and Allanp. These charts are now updated with right values. The 5292 is by far the most powerful guy, 60% more than PF-XL!