Are battery extensions legal?

Just wondering if battery extensions are legal because I have seen several teams such as 7090 using them and our team was thinking of adding them as well

It’s legal in VEX U. But I don’t have any information for VRC. My money is on no, as Cody asked the question using the custom electronics rules in the VEX U Appendix.

Your best bet is to ask Karthik here.

For Vex U they are legal. Non Vex U I would guess no because Vex does not sell them. Only a guess don’t only go on what I said.

Can’t find the exact thread(s) right now, but it was ruled multiple times that they are not allowed (EDIT: In VRC). Battey extensions, or at least longer wires on the batteries, would help a ton with battery placement. Another advantage of extensions is that they can be used to minimize plugging and unplugging with the Cortex and Power Expander. This way, if a plug breaks, you just replace the extension instead of trying to fix the Cortex.

I’m really hoping that VEX comes out with some sort of extensions. :slight_smile:

If you mean a battery extension cable, that is, a cable that goes between the battery and the cortex, then they are not legal for the high school (or middle school) vex robotics competition.

However, perhaps you mean something else like a power expander that allows a second battery to be used for up to four motors, these are legal.

I am not sure if they actually extended their wires.

They were around in Singapore recently for the Skills Challenge, and we had a good look at their robots. Don’t recall seeing any extensions.

I really want an extension. We have had to send in countless cortexes for repair because the battery connection is broken. This could be avoided if we had extensions.

Are you not attaching your batteries securely to the robot?..

We had some people on the team at the beginning of the year who seemed to think “Get me the robot battery” means “Pull awkwardly on the cord part of the battery at an upwards angle until it either yanks free, the battery cord pulls out of the plastic housing, or you give up and make me do it.” It took me 8 months to explain how to remove batteries without damaging them or the Cortex.

They managed to make the battery port on two of our Cortexes so bad that if I rammed the robot with another, the battery terminals would actually come loose and cause the Cortex to reset. We blew an entire competition because the robot would stop moving and have to reconnect every time we took an impact. I had to RMA that one.

Never underestimate the power of human stupidity.

Yes, kind of like this. Thanks for elaborating. I over exaggerated when I said “countless” cortexes…It was only two. We have had them for 3 years now, so, I guess it’s not too surprising that the battery connection was loose. However, they could have been good without repair for another 3 years if we had an extension.

Vex needs an extension cable. They really do, but I can see why they don’t want teams making one. Do a poor job and a battery gets shorted and that’s not fun or safe.

I guess college kids can handle the occasional fire here and there (I’ve started two by accident in my bedroom as a teenager), I now own at least a few of those canned fire extinguisher thingies. If you’re curious about the fires, one was a PS2 the other was a EVGA motherboard. In both cases I managed to avoid setting anything else ablaze, either that or firespread was disabled on the server.

The point being, blah we don’t really have a solution for you.

For those wanting to make an extension cable anyway, these products will get you started:



Crimping Tool (if you need one):

Our Cortex encountered the loose battery problem before state last week. We used a tiny flathead screwdriver the bend the female socket in the cortex a bit closer together so it could get a better grip on the pins of the battery. No issues whatsoever with any of our batteries since then.

When that problem occurs during competition we wrap two to three rubber bands around the connection securing it during the match so it should not cause any problems after it is determined there is a loose battery connection.

One thing I suggest in respect to battery extension and a loose battery connection on a cortex. My team uses a battery extension at all times when we are practicing or testing anything made from one end that looks like the power expander connection which connects to the battery and the other that looks like a normal battery connection that plugs into the cortex. Then for the tournament we carefully plug the battery directly into the cortex. We have done this for the whole year and have produced no problems with battery connection because the port is used much less. If we were able to use it in the future for competition we would never have mess with the battery port on the cortex vastly increasing the length of use for the cortex and less technical problems during competition. I can post a picture if you would like to see our practice only battery extension cable to help save your cortex.

I’m almost positive that I’ve seen them in some videos where their batteries are placed near their front wheels, impossibly far away from the Cortex. Maybe they switched it up for the skills challenge, hmm.

It is possible to have that setup. On my robot the cortex is located near the back of the robot, and the battery placements are right behind the front wheels. Its just a matter of cortex positioning and battery placement to get the cortex in the back and the batteries in the front.