$4 gadget to prevent using dead batteries at competitions

Hi! This is a product that I designed that you plug into a vex battery that then will display the voltage of said battery. The intended use is for when you are preparing your robot for a match at a competition you plug this into your batteries to check if they are charged before plugging them into the robot. Here it is in action! https://youtu.be/6x9E79ilF1A I’m going to be making these by hand, and will be selling them for $5 online. They will be available for purchase when parts arrive and I have a small stockpile made.

Antichamber is at it again people!

Somebody was offering similar voltage testers printed in bright orange color few years back, but I couldn’t find that thread. (I found only these: 15341, 17675, 24373)

Putting them on a keychain or lanyard, as @antichamber suggests, would actually make it very convenient and so much harder to forget at the pits.

@antichamber, if you are going to design and 3D print a custom case, may I suggest a couple of modifications for “deluxe” version.

  1. You could add a 2-pin dupont female connector to plug in a motor or y-cable. Seeing voltage drop as you run the motors is a good indicator of how much power it consumes. You could estimate the friction loses, output load, etc…


Last year I made a bunch of these and was giving them out as on-the-spot prizes, when I was pit judging. (they were not 3d printed but hot glued and looked ugly)

  1. Since you 3D printing, add a couple of holders for 5/64 and 3/32 L-keys and, maybe, even a combo wrench.

  2. Add a hole or two to hold spare 6-32 motor screws, an 8-32, as well as pegs for a shaft collar and a nut - a nano toolbox on the go.

  3. If the final product could be mounted with a small loop of VEX chain that will look awesome!

Great idea. I just want to know the price. Is it $4 like what is said in the video description or $5 like it says in the post?

Hope you sell a bunch of them.

I’ve already ordered five…

How do I order one?

Go to his youtube channel and go to his Schlucas lift testing video (which I’ve linked here )
and in the description of that video will be a link to the voltage readers. In all seriousness, if vex sold these, they would be there best seller. Thank you so much antichamber!

Can I preorder like twelve of these?

We had an issue where we thought we grabbed a new battery and we actually grabbed a dead one. For elimination. In the second round. Yeah.

For our last competition we ended up using one of our alliance members’ robot for elimination because they had an LCD with battery displays.

@TheColdedge Order a few of these. At least 2. 4 would be better.

Just bought one :slight_smile:


Vex Battery Voltage Tester

That is the link for the Voltage tester

Every team should either make or buy one of these.

lol. Or like, use a half decent multimeter (available anywhere) which will have a more calibrated value anyway… not to mention 100x the utility…

We have been to competitions with very limited time between matches, especially during the elimination rounds, and many times the team will stay at the field and send one person running back to the pits for batteries. Because we also have a freshman team that struggles with organization, it can be dangerous to trust that all of the batteries in the “charged” pile are actually charged. The robot has code built in to read and report the battery voltage for both batteries via the LCD, however that requires them to get the battery, return to the field, plug it in, turn it on, wait for it to connect, and then read the LCD to determine if they need to make another trip.

This tool would allow whoever they send back to the pit to quickly verify that the batteries they are grabbing are actually charged. This is also far more convenient than a DMM. We have one, and we use it, but this tool has value. Pinpoint voltage accuracy and a wide range of features isn’t the selling point of this tool.

I’m glad to see that people are enjoying my product! Sorry for the recent shipping delays, I haven’t had time to produce more of the testers, hence why I haven’t shipped them out

As long as I get mine before Saturday, next week, I don’t mind.

Very cool, im not sure if this will work with V5 and it would be cool if you or someone could make a updated version for the new battery.

It definitely won’t work (the battery connectors are very different). It probably won’t be terribly necessary anyway, as the batteries have built-in charge level indicators.

I mean, its pretty useful (and essential), if you don’t have an LCD. If you have an LCD just program it to show the battery voltage.