Vex IQ smart motors moving slowly

This will help on the motor model change over.


I guess I’ll call support now thanks for the help!

I think that it is now established that VEX IQ did indeed do a motor change, and what I said was from my experience (so not a completely tested theory). All I know is what I said, and that sometimes we will have to experiment with different combos of drive motors to find the right ones. It seems as if @ReMiSyS is having the same issue as I am with the motors (I just accept it as part of VEX IQ motors). Another thing is that these motors are brushless, meaning that if you use one, say in a DR4B, and combine that in a drivetrain with a new motor, one side will lag behind the other. Thank you @Foster for helping @ReMiSyS figure out the problem. And my opinion is that you should buy new motors (that is just what I’d do, not what you have to).


Yep, you did. But it’s not really acceptable that the new motors don’t work as well as the prior models. That is something that VEX needs to address.

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You’re right, it’s not acceptable, and when we figured out that VEX IQ did this on us (after we’d bought 10 new motors for worlds), we were really upset, and we contacted VEX IQ. They said that the motors were exactly the same (which obviously they aren’t) and that is was tough luck. If you can get through to them, please let me know! Thanks.

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have you tried programming the speed to make it faster

Yes. It doesn’t work

hmmmmm… are you using robotc

I used the VEX IQ code blocks. It doesn’t make a difference from driver control

i can’t help you i am only using robotc so i am not familiar with the program you are using

It’s okay I e-mailed support, waiting for a response.

ok good luck and i am happy that i tried to help :slightly_smiling_face:

For the record:

  1. We did replace the original injection molds for the VEX IQ Smart Motor in 2018. Motors made from the original molds have a datecode that ends in “DD” while motors made from the replacement mold have a datecode that ends in “AG”.
  2. Nothing fundamentally changed in the design or operation of the Smart Motor during this replacement. We tweaked a few minor interior features to improve manufacturability and injection moldability, but otherwise they are functionally identical. Every Smart Motor goes through functional checks at multiple points during the manufacturing process to verify these motors meet our requirements.
  3. The Smart Motor is not a brushless motor, it is a DC brushed motor. We’ve been using the exact same model motor from Mabuchi inside all Smart Motors since VEX IQ launched in 2013, as we’ve been extremely pleased with the performance of this motor. The only brushless motor currently found in any VEX products is the VEXpro Falcon 500.
  4. Brushed motors typically have a ±10% tolerance band for operational specifications in mass production from their nominal datasheet values. We software limit the performance of motors at the top end, which can mostly mask these minor performance differences (and differing battery voltage levels) in most real life applications. However, in extremely demanding applications (like climbing in VIQC Next Level), minute differences in individual Smart Motors and Robot Batteries had a visible impact on robot performance, as many competitive VIQC teams were running their hub manipulators / climbing arms right at the threshold of what was possible to maximize speed of scoring.

Thanks for the great response @Art_Dutra_IV!
In this case @ReMiSyS motors are from the same molds.

The better motors are from batch 5151DD, the lesser power ones are from batch 5191DD, I’m assuming these are a later date. They are saying that there is a substantial difference between them (more than the 10% that you mentioned)

Is there some way teams can test the motors to help sort them?