portable controls w/o using tether

yo, Team 1505 here, one question, is it possible to walk with your robot and drive it at the same time with out using teather cables. the only issue is getting power to the user interface and the radio

if anyone has a solution to this problame let me know

You can safely power the OI from a robot battery or something smaller, as long as its in the 9-12 V range. We have done this many times. Just destroy an OI AC adapter and hook up the wires to your battery, paying careful attention not to reverse the polarity.

Yes there is a way, Very Simple as well


It’s one of the many things that us FIRSTers have put together to make life easier. =)

Powering the OI is only one half of the problem as originally posed… You still need the tether for communications. Use of radios in the pits is forbidden…

As stated above you can infact run your OI off of batteries, its quiet simple, you dont have to butcher a power supply if you dont want, you should be able to buy the connector as its a standard size, although that size espaces me right now, and just connect a batter to it.

As stated that is only half your battle as FIRST forbids the use of radio communication during competition. If your talking about just doing this for a demonstration or a parade, then your fine, but this wouldn’t be possible at competition due to the radio restrictions.

Hope this helps.


Yes, you can buy the right sized barrel connectors at Radio Shack or your favorite electronics store, or if you have some old adapters laying around (that have the right size end) just chop off the adapter and you have a nice long wire attached to the barrel.

Thanks for posting that thread.

Here is the link mentioned in that thread to my white paper on how to make a Portable Power Pack for the OI:


If you have any questions just let me know

Your welcome and my fault for not mentioning that if your gonna do this at competition that you MUST use a tether so that the robot doesn’t interfere with other robots in the pits or on the field - sorta like a direct link to the robot with out the use of channels =)

Can you use one of the blue rechargeable RC backup batteries? Do they have enough voltage to run the OI? They’re about 7 volts or so.

I asked IFI that a couple of years ago about using a 7.2 NiCd rechargeable and they said it’s a bit under powered and to go get a 9.6 rechargeable from RadioShack, the kind for RC hobbies. Then just splice a barrel connector in parallel to the connector on the rechargeable battery and poof your ready to go and you can still easily recharge it.

yea, we just need it for a convention at the salt palace in salt lake city in a few days

Yea, this year i powered my team’s controller with the little blue batteries. Surprisingly enough the OI will operate. Our batteries were always overcharged by the charger. But as the batteries die you will notice strange OI behavior, luckily when the batteries start to die the radio is the first thing to stop working.

My team and I built a portable OI powersuppy using a recharble 9.6V nicad battery from radioshack. we built an adaptor cable to take the battery end and convert it to what the OI uses so if we find we need more batteries for longer demenstations we don’t have to modify them we can just go to radio shack and buy them.

I built an OI power system into our custom operator interface with 3 9v batteries and a jack for wall power. there is even a swich to change modes. our captain, who asisted, will probably post a picture of it later. my project for next year’s oi is to make a rechargeable system that autuomaticly transfers. to do this, i need to find a 9.6 volt charger that can support the drain of chargeing a battery and powering an oi at the same time. does anyone know if this has been atempted before?

Am I reading this right? This will essentially be a mini-UPS. That is a really neat idea!

If you do this, you’ll need to limit the current flowing into the battery pack, otherwise you could damage it.
Otherwise it would be totaly possible to do. Just use 2 schottky diodes that can handle the current into and out of the battery, and a resistor on the one that will be used during charging. That will make sure you have enough current to power the OI, but don’t toast the battery.

Attached is the OI power system the captain and I made. It has a wall jack for 9v input and the transfer switch is near by. in the lower right corner, three 9v batteries are visible. In my previous post, I mentioned that I was making another one. It’s still under construction because I discovered the charge controller I was going to use from a backup battery charger wasn’t in use for a good reason (It smelled like a burnt victor and, upon further inspection, I discovered one of the IC’s had violently lost half it’s mass at some point).



WHOAOAOA!!! The picture (discussed about 1 post below yours) has 3 9v batteries!!! Can the OI safely work on 3batt * 9v = 27volts? Just curious :smiley:

The 7.2v backup battery works just fine.

“I know, I’ve seen me do it”

If you are planning on a very long presentation or something of that matter, wire up a simple bus to connect 2 or 4 in parallel. The gentleman from IFI used just one when running diagnostics on peoples robots at our regional in Detroit.

Those batteries are running in parallel, not series. Therefore, the voltage is still 9v. This is done to increase capacity, or, run time of the OI while being run on batteries.