VEX V5 Motor problems

During our season, our team has been coming across a small problem: we have been using a 600 rpm cartridge for our flywheel and after about 40 seconds of running, the speed dies down and eventually comes to a stop and can’t move on its own anymore… we even tried switching motors, gear cartridges, etc. and the problem still persists. I cant tell if its a burn out or a dead motor, but any advice would be helpful since our competition is like two weeks away.

Likely overheating due to friction in the mechanism.

Look on the V5 Brain - Devices → Brain → Event Log
it should show you if motors are overheating.

Resolution is to reduce friction by having a high quality build.

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Most likely you are asking the motor to generate too much force for too long, which results in motor overheating and its firmware entering thermal shutdown mode to protect it.

See these posts:

Try to reduce the friction.

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You probably have an overheating problem. Are your motors hot?

it says that motors reached heat level 2 during some of the previous testing.

We were running some diagnostic testing on just that motor alone in the devices section on the brain and amping up the rpm and it was holding a steady 600 but dropped after some time. It looks like it is an overheating problem. The motors didn’t seem super warm, but the axles it connected to were burning.

Many teams will go desperate measures using cold spray… that is not engineering - just treating the symptoms.

Best to share picture of mechanism and you will get feedback on improving build to fix root cause of overheating.

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mars,

Do the motors recover once they are fully cooled off? The motor’s power is incrimentaly reduced at each heat level warning.

Mike

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Put the lines in your code to display, to the brain:

motor rpm
motor watts
motor temp

See what the rpm/watts readings are while 1) free running the mechanism 2) under a load.

If your axles are hot… find out why.

Where is the friction coming from?

Misaligned axles? Why?

Misaligned frame? Why?

Too tight bearings? Why?

Damaged bearings? Why?

Master of all “why” videos…

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From what we tested yesterday, the motor was able to run again after a few mins of sitting but it didnt feel like they weren’t fully recovered. We are going to try again later today. I’ll upload a picture along with it too.

it looks like the motor did make somewhat of a recovery after cooling down overnight. we were able to run it for a full 2:40 until it stopped. the motor was hot and so were the axles. attached is an image of the flywheel setup

I see:

  1. blue motor cartridge
  2. ‘short’ bearings, the ones supported by only 1 screw
  3. motor shaft that’s way too long
  4. way overgeared
  5. green idler gear adds friction

The ‘short’ or one-sided bearings tend to kick up. Bearings, where at all possible, should be placed where the shaft is in the center hole with equal pressure from screws on each side keeps it nice a flat.

Shafts should be as short as possible. In a high speed mechanism like this, short shafts decrease the chance you will have a vibration from balance issues.

Go to the brain/coding. Get the data. This is a great opportunity for a notebook entry.
Problem: slowing down
Suspicion: too hot
Steps: coded brain to display watts/temps
Confirmed too hot
Resolution…
Remeasure data
conclusion…

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We took your advice.

After changing the bearings to the 3 hole ones instead of just the 1, removing the green idling gear, and shortening the motor shaft the flywheel ran perfectly. Thank you everyone for all of your support. We really appreciate it.

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Now document all of this in your notebook.

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