portable controls w/o using tether

[halomaster69]

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

[Pat Fairbank]

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.

[JBotAlan]

Originally Posted by Pat Fairbank

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.

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

[Alexander McGee]

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.

[billbo911]

Originally Posted by JBotAlan

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

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.

[Al Skierkiewicz]

Ok,
I do have to jump in here and say something. Putting batteries in parallel without some protection is a bad idea. The higher voltage battery will try to pump current into the lower voltage battery to equalize the voltage and the cycle will continue until the batteries all discharge. A diode is needed to prevent each battery from supplying current to the other battery. With small batteries this effect may be unnoticed, but it is still taking place. It is a simple matter to buy a 12 volt battery holder (from Radio Shack) and fill it with D cell alkalines and get a 12 volt source with plenty of current. Be sure to watch the polarity of the battery connector so you don't reverse the voltage into the OI.
It is never a good idea to use a charger as a voltage source for the OI. Many chargers, especially NiCad chargers use a pulse method of charging and the peak of the pulse can exceed 12 volts by a considerable amount. Either use a standard 12 vot power supply (regulated please) or a battery. Your OI thanks you, your team thanks you and I thank you.

[eugenebrooks]

Originally Posted by Al Skierkiewicz

Ok,
Putting batteries in parallel without some protection is a bad idea...

I'll second what Al has said, and note that the manuals indicate that the only approved adapter on the power port for the OI is the power adapter that is provided in the kit. If you make a mistake hacking the power for the OI, your OI will escape its warranty.

If you want the convenience of live charging for a battery operated OI, and the lack of risk that providing a regulated supply for the correct voltage to the OI gives, you need to be meticulous in how you do it.
You need to use a battery technology, and charger, that does not induce pulses on the power line, and Al has pointed out the risks of how NiCd chargers normally work on this front.
Your best choice is a lead acid gel battery of a suitable size, and these are likely to come as 12 volt units. I would not apply 12 volts directly to a power port that is normally operated by a 9 volt source. You could swamp the power dissipation capability of any internal voltage regulator in the OI if it is not designed for it. I have not seen technical specifications for the OI that indicate that the power port is designed for handling more voltage, and do see a specific caution with regard to using only the provided power cube on this port.
So, what to do, if you really want the "cool" capability of an OI that can stay live while you connect and disconnect the power line? You need to use a 12 volt gel cell that can handle the current requirements while not being so large that portability is hurt. The 12 volt battery used in the old analog "bag" cell phones is a likely candiate, but you can probably find others. You need to build a voltage regulator that can drop this supply to the voltage required by the OI, the LM350T could be used to get the job done. Measure the current draw from the power port and use that to figure out how much power your voltage regulator must shed as heat. Use an appropriate heat sink and an appropriate insulating mounting for the regulator on the heat sink. Finally, find a battery charger for your chosen battery that is reasonably well regulated, minimizing any ac hum induced on the battery.
It takes a relatively minor engineering effort to put it all together, but you will end up with a useful capability that you would be proud of and the excercise is educational.

Remember, your OI warranty will be voided, but that is often the price of having fun...

[ConKbot of Doom]

2 6v lantern batteries... large, but by no means heavy like a SLA, and easy to find. or 9.6v battery packs, like mentioned earlier.

Or you can make a mini trailer for the robot and have your operator crouch on that with the controls, tethered to the robot, as it pulls the trailer.

[mtaman02]

Yes there is a way, Very Simple as well



http://www.chiefdelphi.com/forums/sh...light=Portable

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

[Mike Betts]

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...

[Josh Hambright]

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.

Josh

[Pierson]

Originally Posted by oneangrydwarf

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.

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.

[halomaster69]

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

[team222badbrad]

Originally Posted by mtaman02

Yes there is a way, Very Simple as well



http://www.chiefdelphi.com/forums/sh...light=Portable

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

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:

http://www.chiefdelphi.com/forums/pa...le&paperid=362

If you have any questions just let me know

[mtaman02]

Originally Posted by team222badbrad

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:

http://www.chiefdelphi.com/forums/pa...le&paperid=362

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 =)