uhh I dont think that this should happen

Today at the scrimmage in NZ one of our robots motor controllers caught on fire just after it turned on, has anyone else experienced this?
from what we can find there were no shorts in the wires or anything that would have provoked this.

Picture Here

I’ve personally never experienced this, but a couple teams who have had the same issue discussed it in this post.

Yeah that’s what ours looked like except the hole was bigger.

Was it a new one? Ours was brand new and it started smoking as soon as I turned the power on.

Also, was it on a power expander?

not sure how old it was, and it wasn’t connected to a power expander

It has happened to us, and I believe the motor controller was connected to our power expaneder.

It has happened to us several time . 3 times to be exact and 2 were from the power expander .

As someone who has had a fire-free robot for 2 years, I see quite a lot of people who have experienced motor controllers catching on fire… I think VEX should fix that.


My teams robot is sitting next to my bed right now. I think I am going to unplug the batteries tonight…

Was the Motor Controller 29 heat sinked? In other words, did you have it zip-tied or mounted to metal on your robot in some way?


It was just hanging between the motor and the microcontroller

Hi Guys,
Yes, we’ve seen a few of these crop up and in each case we’ve tried to contact the people who reported them. In most cases this sort of thing is related to a dead-short on the Motor Controller output (usually due to some sort of wire damage).

Some things to note:

  1. All of the materials in this item are self-extinguishing – as soon as power is cut, everything will stop.

  2. There are hundreds of thousands of these units in the field, and we’ve seen only a handful of failures. We have no reason to believe there is any systemic flaw at this time and don’t believe anyone should have reason to be nervous about using these products.

  3. This is not the “expected” failure mode for this unit in that situation, so something “weird” has happened in these cases.

  4. We’re investigating in more detail. If you have a unit which failed in this manner, please contact our support folks (903.453.0802 or support@vexrobotics.com) and they’ll send you a new unit in exchange for the failed one. We want to take a peek at the failed ones and see if we can pinpoint what happened.

If you have any concerns or questions, please feel free to contact me directly.


John V-Neun
Director of Product Development
VEX Robotics, Inc.

Didn’t have quite that problem but at the last competition in Vancouver, my controllers batteries blew up in the controller. we scrambled to replace them but the controller was shot. i don’t know how that’s relevant but I’l post it anyway

It might not be really relevant to the main thread, but I’m glad you mentioned it. I was at the competition (I’m assuming you mean the Cambie tournament) and didn’t know that this had occurred.

I’m not quite sure what you mean by “Blew Up”. Can you give us some detail where (on the scale from “leaked a bit” to “levelled three city blocks”) this particular blow up lies? Photos would help if you’ve got them, particularly a photo of the batteries in the controller before you pulled them out. That would address issues of “was it a Cortex or a PIC controller?”, “were they VEX batteries?” and “were they correctly installed?” but could also provide evidence of any other more subtle flaws. While I’m suggesting quesitons that could help identify the problem… were you using a VEX charger or an aftermarket charger?

If you happen to have an equipment failure like that again at a Vancouver area event you are welcome to ask for me (Jason) at the tech inspection table. I’d be happy to help you document and report the failure so that John and the people at VEX have as much information as possible to help them identify the issues at play. I’ll admit that it isn’t always easy to do that given the time constraints of a competition, particularly after the tech inspection station has closed… but we’d like to help.

It has been my experience over the past nine years (yep, I’ve been using IFI stuff since before VEX came around) that IFI and now VEX care very deeply about providing a quality, reliable product. The more detailed information we can give them when something unusual happens, the better job they can do!