View Full Version : running the OI off a battery
We need to run the robot on radio while away from the plug. I went out and bought an M-type connecter (the kind that the DC-In port on the OI uses) and soldered it to a 9 volt battery (cause the power adapter SAYS it outputs 9v)
but the problem is, that, when tested with a multimeter, it shows that the power adapter ACTUALLY outputs 12 volts.
will the OI run on 9 volts?
Jeff Waegelin
04-04-2003, 19:35
Well, from the writing, the power adapter says it outputs 9VDC, 1500 mA. I would assume 9V would work, but I'm very puzzled as to why the multimeter gave you a 12V reading... Try it again; maybe you had something messed up.
well, it makes sense, considering the OI gets 12v through the tether and the competition port.
though don't know why it says 9 on the adapter.
Dave Flowerday
04-04-2003, 19:45
Originally posted by Aonic
We need to run the robot on radio while away from the plug. I went out and bought an M-type connecter (the kind that the DC-In port on the OI uses) and soldered it to a 9 volt battery (cause the power adapter SAYS it outputs 9v)
but the problem is, that, when tested with a multimeter, it shows that the power adapter ACTUALLY outputs 12 volts.
will the OI run on 9 volts?
The OI should run on 9 volts, however I'd be surprised if a 9v battery lasts more than about 10 minutes! You'd be much better off hooking it up to a spare robot battery (it'd be a good idea to put a fuse in the line if you do this though).
The reason the OI power supply seems to put out 12v (I actually measured ours at 14) is that it's an unregulated supply and will output a higher voltage when there's no load connected to it (credit this answer to Al S. as I just asked him the same question last week!).
haha. the 9 volt didn't last very long (about 5 min) and the OI started doing constant resets after a while (PO5...5...3...2...1...1072...PO5...etc)
after discovering that, we made a quick run to radio shack, found a aligator-clip to car-12v-socket adapter, and a car-socket-adaptor to 9volt Mplug adapter (for about 20 bucks total) hooked em up to a 12volt battery, and used that :D
anyway, thanks for all your help! =)
Why not just power it through a competition port dongle?
All you need then is a 25 pin connector (or a 25 pin cable chopped in half) and a battery.
*shrug* seems cheaper, and you can put in switches for disable and auto mode while you're at it. It's something I've been meaning to do for a while now. I would like to find a better power source, something in between a 9 volt dry cell and a bot battery. I was thinking an old laptop battery, although it is rated at 14.4 volts. I know nothing about the power system of the RC, so I won't try it, yet.
But it would be so cool.
Maybe if I get bored in the pit...
-Andy A.
Josh Hambright
07-04-2003, 12:06
Last year we had a switch on our control board that would switch the power from a surface mouned plug for the wall wart adapter that the OI normaly uses to a bunch of AA batteries we had under the top of the board...very useful when doing demonstrations, or just to drive your robot around to move it from point A to Point B
Lloyd Burns
18-04-2003, 10:13
Originally posted by Andy A.
Why not just power it through a competition port dongle?
All you need then is a 25 pin connector (or a 25 pin cable chopped in half) and a battery.
*shrug* seems cheaper, and you can put in switches for disable and auto mode while you're at it. It's something I've been meaning to do for a while now. I would like to find a better power source, something in between a 9 volt dry cell and a bot battery. I was thinking an old laptop battery, although it is rated at 14.4 volts. I know nothing about the power system of the RC, so I won't try it, yet.
But it would be so cool.
Maybe if I get bored in the pit...
-Andy A.
Comp Pport has a 15 pin connector !
Lloyd Burns
18-04-2003, 10:30
Crescent (#610) has used a battery pack for several years; a battery holder with AAA cells and a connector that goes in to the power connector used by the 1500 mA Wall Wart IFI supply. I don't know if they use 6 or 8 cells in series.
It seems reasonable that IFI would use a regulator on the power input, so it might not matter. but the power input is a diode away from the tether power supply line.
Practically every Wall Wart gives the rated voltage only if loaded down to the rated current, depending on the resistance of the transformer secondary for this "regulation". I'd design the "9 V" input to handle 12 V at least, and the 7800 Regulator line can handle 18 V max rated.
camtunkpa
18-04-2003, 10:33
We have used a power pack to run at many outdoor events with our machine.....we use four 9 volt batteries hooked in parallel which gives us a good amount of run time on the interface.
Kyle Fenton
18-04-2003, 11:27
Originally posted by Andy A.
Why not just power it through a competition port dongle?
All you need then is a 25 pin connector (or a 25 pin cable chopped in half) and a battery.
*shrug* seems cheaper, and you can put in switches for disable and auto mode while you're at it. It's something I've been meaning to do for a while now. I would like to find a better power source, something in between a 9 volt dry cell and a bot battery. I was thinking an old laptop battery, although it is rated at 14.4 volts. I know nothing about the power system of the RC, so I won't try it, yet.
But it would be so cool.
Maybe if I get bored in the pit...
-Andy A.
Be careful when you do that. Innovation FIRST will void your warantee if you try to power it through the Competition port on your own, and it screws up. From what I can tell you, the OI gets its power from Pin 1. I believe when you power the OI from the Competition port you un-lock more channels than you get with a regular dongle. To check the voltage of the OI you can measure it from Pin 1 to a ground (Pin 8).
FreeBSDboy
26-04-2003, 12:06
The wall power supply for the OI (like most brick style plug in power supplies) will not regulate properly with no load. So if you took the voltage reading with a multimeter while you wern't drawing any current off of it, it will read abnormally high. If you were to test it under load, I would bet the voltage would drop to ~9V.
team222badbrad
26-04-2003, 12:54
Correction to CAMTUNKPA...
We use 3 9 volt batteries hooked in parallel. Yes and when the batts die the controller cuts out.
I have used 12 volt power packs plugged into the operater interface and it does not seem to harm them...
i dont have one of the powers supplys on hand, and so i have a question, Which part of the plug is positive and which is negative? i need the info to build one.
thanks
We've been using an old (can't hold a charge, etc etc) robot battery to power an equally old OI. It's been working since December, and we only charged it once. :D
Greg Ross
26-04-2003, 20:47
Originally posted by ZACH P.
i dont have one of the powers supplys on hand, and so i have a question, Which part of the plug is positive and which is negative? i need the info to build one.
thanks
The center contact is negative, and the outside is positive.
Joe Ross
28-04-2003, 08:46
Originally posted by gwross
The center contact is negative, and the outside is positive.
Are you sure? Generally on power supplies like that, the outside is negative. This post says the same thing (although it is old): http://www.chiefdelphi.com/forums/showthread.php?s=&threadid=11422&highlight=power+adapter
Andy Brockway
28-04-2003, 10:24
Last year we planned on running our robot in a local parade. I e-mailed IFI and this was their response:
'12V is the max. I know that radio Shack carries a 9.6V battery pack that we use here and at competitions. You will have to modify the connector to fit the OI. This battery pack is like a 4-pack of AA's. Radio Shack also carries a charger for this pack. The connector is a 2.1mm X 5.5mm.'
I do not remember +/- but we ran the robot over a mile without the OI shutting down using this battery pack.
Lloyd Burns
28-04-2003, 13:35
Originally posted by Joe Ross
Are you sure? Generally on power supplies like that, the outside is negative. This post says the same thing (although it is old): http://www.chiefdelphi.com/forums/showthread.php?s=&threadid=11422&highlight=power+adapter
Joe, I have a 12V, 0.5A power supply on the shelf beside me - it gives 19 V OC, and the still attached factory plug on it, which fits the OI power input, is pin-negative. As Apple's monsieur* Gasse' said, "The nice thing about standards is, there are so many of them." I label my supplies with a labeller, now.
BTW, the supply works well as is with a Radio Shack powered speaker. (All by way of saying, don't expect much adherence to "standards" when dealing with commodities from offshore.)
*Jean-Philllipe, maybe, I forget.
Greg Ross
28-04-2003, 19:53
Originally posted by Joe Ross
Are you sure? Generally on power supplies like that, the outside is negative. This post says the same thing (although it is old): http://www.chiefdelphi.com/forums/showthread.php?s=&threadid=11422&highlight=power+adapter No, I'm NOT sure.:o I'm also not sure whether Loyd's "pin negative" is agreeing with me or not, but from the context ("The nice thing about standards is, there are so many of them."), I'm guessing that it means that the center pin of the socket on the OI is the negative terminal, and that he agrees with me.:)
I was going off of the picture on the adapter which is something like the picture below. (I don't have the adapter with me right here, right now.)
Aside from the possibility that I got it right, I admit that it is possible that:[list=1] I misread the picture, and so posted the wrong information.
I read the picture correctly, but mistyped the information.
I don't have the foggiest what the picture really is indicating. (Remember, I'm just a programmer.:) )[/list=1]
That picture indicates that the center pin is negative, and the outer covering is positive, if that is indeed the picture from the power suppy then that is what it is.
Greg Ross
29-04-2003, 01:48
I just checked another (OI) power adapter, and the picture was exactly the opposite of the first adapter I looked at, and the multimeter shows both having the same polarity!
(As I said, I'm just a programmer, but I want to understand.) So which picture is correct? When I connect the red lead from my multimeter to the center contact, I read a positive voltage. This is the same as when I test a battery with the red lead on the positive end. So that shows me that the electrons come out of the center of the plug. (Do I have that right?) But now, is the picture on the adapter supposed to show the polarity of the contacts on the plug? (i.e. the direction of electron flow OUT OF the plug) or the direction of the flow of electrons returning to the adapter?
I'm thinking of something like when you have multiple batteries in series in a flashlight. You have the positive end of one battery in contact with the negative end of the next battery. Should the picture on the adapter be of the first battery, or the second?
FotoPlasma
29-04-2003, 05:48
Originally posted by gwross
I just checked another (OI) power adapter, and the picture was exactly the opposite of the first adapter I looked at, and the multimeter shows both having the same polarity!
(As I said, I'm just a programmer, but I want to understand.) So which picture is correct? When I connect the red lead from my multimeter to the center contact, I read a positive voltage. This is the same as when I test a battery with the red lead on the positive end. So that shows me that the electrons come out of the center of the plug. (Do I have that right?) But now, is the picture on the adapter supposed to show the polarity of the contacts on the plug? (i.e. the direction of electron flow OUT OF the plug) or the direction of the flow of electrons returning to the adapter?
I'm thinking of something like when you have multiple batteries in series in a flashlight. You have the positive end of one battery in contact with the negative end of the next battery. Should the picture on the adapter be of the first battery, or the second?
This is a very interesting problem.
The results you got would be right under two circumstances (to my knowledge): 1) the diagram is wrong, or 2) your multimeter uses unsigned notation :p. Usually, when one wants to test a voltage (and is expecting to receive a positive reading) you'd connect the red lead on the multimeter to the positive terminal, and the black lead to the negative (ground, usually) terminal. After taking a reading, if you were to swap the multimeter leads for one another, you should get a reading that is negative the original value.
I wish I had an official OI AC adapter in front of me, right now.
Think of current going from an elevated voltage (+), going through a load (a light bulb, a motor, or the OI, for instance), and returning to Ground (-). That's exactly what you have when you are given a diagram of... almost anything that runs off DC. So, in actuality, the diagram of an AC adapter is both the positive and negative ends of a battery (neverminding the thought of two batteries being in series).
Another point of note is the difference between "electron flow" and "current flow." There's a nice little description and demonstrative piece on this (rather historic) problem here (http://www.rare-earth-magnets.com/magnet_university/magnets_conventional_vs_electron_flow.htm). (off topic: this webpage begins with this quote: "The nice thing about standards is that there are so many of them to choose from." attributed to "Andres S. Tannenbaum, computer science professor.")
I apologize deeply if I am wrong about any of this. I'll still make the excuse that it's 2:50am, though. :p
Greg Ross
29-04-2003, 12:23
Originally posted by FotoPlasma
Another point of note is the difference between "electron flow" and "current flow." There's a nice little description and demonstrative piece on this (rather historic) problem here (http://www.rare-earth-magnets.com/magnet_university/magnets_conventional_vs_electron_flow.htm).
So that's why I'm so confused!:D Actually, I did know there was some kind of problem like that, but I've never studied it closely enough to remember whether the problem was that negative electrons proceed from a terminal called positive -- or-- that those negative electrons (which are the only things that actually move in an electric "current") are actually flowing in the opposite direction of the supposed current flow.
The results you got would be right under two circumstances (to my knowledge): 1) the diagram is wrong, or 2) your multimeter uses unsigned notation :p.
Well, my multimeter does show positive and negative depending upon where I put the terminals, (but I'm assuming, from your ":p" that you knew that) so one of the diagrams is wrong. But I still don't know which one!
Usually, when one wants to test a voltage (and is expecting to receive a positive reading) you'd connect the red lead on the multimeter to the positive terminal, and the black lead to the negative (ground, usually) terminal.
That's what I thought.
After taking a reading, if you were to swap the multimeter leads for one another, you should get a reading that is negative the original value.
Yep, I knew that.
Think of current going from an elevated voltage (+), going through a load (a light bulb, a motor, or the OI, for instance), and returning to Ground (-). That's exactly what you have when you are given a diagram of... almost anything that runs off DC. So, in actuality, the diagram of an AC adapter is both the positive and negative ends of a battery (neverminding the thought of two batteries being in series).
OK. I guess my illustration of the batteries wasn't such a good one.;) So to restate my question: Is the picture on the adapter of the adapter plug, or of the socket on the OI? (Actually, now that I think of it in the light of day, it wouldn't make a lot of sense to make it a picture of the socket, since it is an entirely passive device until power is supplied via the plug. BUT someone else must have been confused about it too since someone put an incorrect picture on one of those adapters!)
So then, if my surmise is correct that the diagram should be of the plug, (and not of the socket) then the diagram that I posted (which actually does match the diagram on one of the adapters) must be wrong. Am I right?
FotoPlasma
29-04-2003, 13:09
Originally posted by gwross
So then, if my surmise is correct that the diagram should be of the plug, (and not of the socket) then the diagram that I posted (which actually does match the diagram on one of the adapters) must be wrong. Am I right?
Heh. After rereading my previous post, I realized that I didn't answer the question. ;)
If you measured a positive voltage from the center to the shield of the plug on the AC adapter, and the diagram on the AC adapter itself is what you previously posted, then yes, the diagram must be wrong.
Actual measurements always take precedence over diagrams.
It really worries me, however, that a mixup like this could have happened... Someone might seriously damage their OI if they misinterpret the diagram...
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