motors slowing down after little use of program

My motors have recently been slowing down after maybe 15 seconds of use the 2 motors that are doing this are my claw motor and the motor on 1 of the arms that is by itself. What happens is after a little use the motors just randomly start slowing down which messes up my programming skills and slows down driving in a match. But what is weird is that it only slows down 1 way on 1 motor(arm) and both ways on the other motor (claw) sometimes it doesn’t even heat up. Can someone help me with this.

Aloha nathanpitts2002,
We noticed the same thing after upgrading the new firmware. We use Modkit. Did this happen to you after the update?

Yes, that is when it happened to us also.

Okay.We have been experiencing problems with the upgrades. We are still trying to work through it.

In our competition last saturday we just kept switching motors when they started slowing down thinking that they were burning out

We switched motors at first. When we were running our belt feeders we noticed it slowing down also. When we tried again, it was at full speed and then started slowing down. This cycle kept happening to us. I was thinking that some type of code in the brain could be confusing itself. This problem comes and goes in the course of running our robot. I hope someone can help. We have a tournament this Saturday Jan 17.

Hi nathanpitts2002 and ipanavigator,

We’re sorry that you have encountered this issue. We are currently investigating a possible software bug that may be causing this behavior with the motors.

If you have any questions or concerns, please contact our technical support folks at or by calling +1-903-453-0802 so we can help resolve this situation.


  • Art

Thank you Art. I look forward to your update.

In Puerto Rico teams that upgraded are having the same problem. The motors are overheating with much less effort than before. What we are doing to avoid this is… (1) Wrapping the motor with a humid paper towel between matches in competitions… (2) we place the robots next to a fan for a couple of minutes every 3-5 matches during practice days.

Still it would be nice to correct this issue since it sometimes gives me problems closing the claw and makes us loose precious seconds of our routine.

Aloha Kaveman,
Although we have not tried your method of cooling down the motors between matches we have tried our own “quick fixes”. These temporary fixes by no means solves the problem. This Saturday we had a competition. My team won but it by no means was pretty. The robot’s operation and skill of my team was that of an airplane pilot trying to land a plane with only half the motors running and half the landing gears not operational. It really wasn’t pretty. Being the event coordinator I was able to talk to a lot of the teams. The majority of the teams with problems have attributed it to the firmware upgrade of the brain (1.13) and controller (1.04). We have our state championships in 4 weeks and these posts in regards to the problems have gone on for at least a week. I hope VEX can offer a solution soon. I wonder if VEX could just give us access to the previous version until the bugs are worked out?

There are several variations of this issue by description. However the reported problem is the same. In addition to this slowness randomly after some use, you may even loose remote link for a second or two. This has been happening since firmware 1.10 onwards but more prominent in 1.13. We have 1.12 on one of the computers but have not tried going back to it (brain 1.12 controller 1.03 is the combination I think). Even the joystick UI was better before.

I have recently asked in one of the other forum topics. Art Dutra instructed me to send an email to vex support and request a copy of the previous firmware version that I was looking for. I just sent it yesterday and hoping that I will get a response today so our team can get to practicing. Maybe your team could send a request to VEX support also and request a past firmware.

Aloha Art,
Eli sent me a copy of the previous firmware and instructions. I downloaded it without a problem. Now the robot is working “top notch”. Thank you again for you and Eli’s assistance.

Hi ipanavigator,

Can you please share the previous firmware (upload it to dropbox or onedrive)? I already sent an email to support but i haven’t received it yet.

Thanks a lot

It would have probably helped if Vex posted those links and instructions here for everyone to access. We thought to downgrade also but it was already night time and a tournament in the morning. I thought we had this version on an unused computer but the program auto-downloaded current version as it had internet access.

Totally agreed. This is urgent, VEX/ipanavigator please share it ASAP, our tournament is this weekend.

Hi surgeon and chitoQ,

We will have written instructions and the firmware files posted online tomorrow.


  • Art

We had to change the our claw gearings to deal with this issue, but if you could fix it would be awesome. We had to change to a very high torque transmission in the claw cause sometimes the motor would simply not move. Now it moves slower, but at least we can count on it closing every time, but it is only giving us 1-2 spare secs when we had 4-6 secs of spare time.

We have practiced the routines a lot to make sure we come up with our max score, but if the motors don’t heat up and start working slowly we will be able to drive more carefully specially when building the highrise.

For what it’s worth, I think I can explain what’s happening. This doesn’t have much to do with firmware versions, but it may be more of a problem with one version than another.

If you want to see for yourself, have the program display the motor current on the brain, and you’ll see when it gets over ~1000, the motor stops functioning as desired. I’ve seen this happen when the program tries closing the claw farther than the claw can actually go, and holding that position. (like when grabbing a cube. The claw may not always be started in exactly the same location)

One solution is to make sure the program loosens it’s grasp on a cube. Of course, you need to make sure it doesn’t go too far.

As Kaverman has seen, changing the gearing gives you more slack as far as how tight the claw must be.

Generally, this is a hardware (robot design) problem, not a software/firmware problem. However, much like other design issues, it can be fixed in software.


How do i display the current that is being sent to the motors on the LCD of the brain in robotC text - based?