VEXnet Joystick Batteries

Hey, our team “99” recently upgraded our robot with the new Cortex micro-controller and joysticks. After getting it to work with VEXnet, we started testing user control and autonomous. We bought some cheap single use AAA’s to use in the joysticks, but after about 1 week we have already gone through too many sets of batteries :eek:. We bought Eneloop rechargeable AAA’s,but I’d like to know what other teams are doing to overcome the constant replacement of batteries, how long do they last on game days, and how many sets for each joystick do you need for 1 competition. Oh and if there is a way does anyone know if its possible to charge without taking them out of the joystick.

I’d recommend when programming keep the joystick tethered instead of using WIFI. The WIFI keys draw a lot of power from the little AAA batteries.

wow, that defeats the whole purpose of “wireless programming”
you can also hack the battery slot, so u can hook up the old controller batteries on it
search a little and you will find a tutorial on how to do that somewhere here

At a scrimmage today, where we played 12 games altogether, we went through 2 sets

my mistake, i have just been informed we went through 1 set of batteries only, and the joystick is still green

1 set of what? Be more specific please. What brand are they? What product name/number?

i would think that spending 20 minutes (and a few bucks) to make an adapter for using the old batteries and to hold them most people would just go with rubber bands, but the joystick has 2 threaded screw holes which could be used to make a nice holder

sorry, we are using Panasonic HHR-4MPT rechargeable which are 800mAh Ni-MH AAA’s

Thanks for the replies. We finally got to test out our new Sanyo Eneloop’s, 800 mAh rechargeable AAA NiMH. The controllers were on for more than two hours, i can’t say the exact time, but i would guess maybe two and a half + hours. The second controller which does not send Vexnet is still fine after running for more than three hours. The set of six recharged in about an hour in the vex AA/AAA Battery Charger, so we only need two sets of six per controller to have a constant supply. I hope this works for us and other teams, our first comp is this week so were all hyped up! :smiley: We might look into the hack, but at $150 the controllers are expensive to mess with.

The battery ‘hack’ doesn’t actually mess with the controller, as it routes the cables through gaps in the housing, and supplies power via dummy batteries.

you pretty much get “two dead non rechargeable batteries” solder leads on them
add a battery plug on the other side of the leads (so you can plug in the old batteries)
and put in the “two dead batteries” in the first two battery slots.
you are not doing anything to the joystick in any way

Just make sure the batteries don’t stay in the joystick too long, and you may want to use something else in place of dead batteries, as they may leak and ruin your remote.


Well I think we’ll just use the rechargeable batteries they’re working great right now. But about using dead non-rechargeable batteries, i heard it was possible to recharge them. I don’t know what type or what size but i thought it was interesting. I doubt it actually works or is safe though :rolleyes:

it is NOT possible to charge disposable batteries!
the chemistry in them just doesn’t work that way
please dont plug them in and have your school burn down (no, seriously!)

Actually, it is possible to recharge non rechargeable, just not with conventional recharges, and they can only be charged a small number of times. They have to be recharged a lot slower as well, as they aren’t designed to be recharged, and more heat is created.

However, it isn’t very practical for this application, it can have its uses, but for the joystick it just aint worth the effort of building a special charger, when it can still only recharge them a small number of times.

Just go get several sets of decent recyclables.

then again, if you already have a special low current charger…

I was also interested in this question and this thread has been really helpful. Has anyone found a good 12 slot battery charger? I am a little disappointed that the guys at vex did not come up with this on their own. The joystick needs 6, you want 6 on charge, most teams use two joysticks, so you need 12 on charge not just 8. It is the classic hot dog dilemma, hot dogs come in packs of 10 and rolls in packs of 8.

My team was wondering how long a set of the AAA batteries that VEX makes lasts in a competition setting. Also, do the batteries have a “memory?”



Batteries chargers are very expensive to have custom made. This 8 bay charger was the best that we could find given all of our constraints (mainly cost due to our education market) that would do some amount of customization (color, text, and packaging).

Put it this way. You can buy 3 8 bay chargers for less than one 12 bay charger would have cost if we had to custom design it.

We felt the current solution was best.


We’ve found that the control with the key will last about 8 matches. So they need to be replaced at lunch on a regular meet. The partner controller will last all day. So the average team needs 18 AAA’s. (6 morning, 6 afternoon, 6 all day)

The 12 cell AAA charger that does 9V backup battery for $65

Paul is right, buy COTS, it’s cheaper. Vex branded COTS is about the same price as other chargers. Or you can buy 6 cell COTS chargers for less. In our case of trying to charge about a billion battery sets for 15 robots, the 8 slot chargers do well.



Thanks - that helped a lot! :slight_smile: