Running PD Board from an outlet
 

The battery I have with me has completely died for our test programming/electrical board.

I was wondering if I could run the PD Board from power from an outlet instead? Obviously not directly connected.

I was thinking one of those AC to DC Car lighter convertors. It would still be 12 volts. Here's an example http://www.amazon.com/Universal-Ciga...ref=pd_sxp_f_i

I have one of those around.

Has anybody tried this and been successful? Or is it just a really bad idea.

Re: Running PD Board from an outlet
 

I doubt that would get you enough current do run anything. You might be able to run the cRio and digital sidecar, but certainly not any motors. The CIMS (on the robot) are wired to 40 amp breakers, I doubt that even puts out 1 or 2 amps.

Re: Running PD Board from an outlet
 

We have no motors or Jaguars hooked up. Only the cRIO and a digital sidecar. Everything else is either not connected or already powered via a power strip on the board.

Re: Running PD Board from an outlet
 

Some of the switching supplies in the PDB are not very friendly to this approach. I strongly recommend staying away from it unless you really know what you're doing.

Re: Running PD Board from an outlet
 

By "not friendly" you mean they are only going to work for a specific setup? If so, what is it looking for? I've moved on to the idea of using a laptop 12 volt power supply instead as it would probably be closer to the correct voltage and provide enough current. If I knew what they are looking for I can try a different power supply that is more appropriate easily.

Re: Running PD Board from an outlet
 

Could you use a desktop power supply like this to power the whole robot with motors and all? At 12V/135A, it provides more current than the main breaker can handle anyway, right?

Re: Running PD Board from an outlet
 

Where did your 135A stat come from?

Re: Running PD Board from an outlet
 

12V@135A is listed on the spec page on newegg for the linked power supply.

Re: Running PD Board from an outlet
 

A pc power supply like the one from newegg could run the robot.


to power it on, connect the thin green wire to ground on the motherboard connector.

Re: Running PD Board from an outlet
 

If you just want to program things and not make anything move, any clean 12V >30W power supply will do. The original part linked is likely to put out incredibly dirty power, I would not try it. The power supply module linked will likely work nicely.

Be sure not to use the battery charger as a make shift power adapter - they can interact poorly.

Re: Running PD Board from an outlet
 

If you're making and buying things, why not just get an extra charger, it will likely have more uses to you and your team.

Re: Running PD Board from an outlet
 

Eric,

What power supply wattage would be needed to run motors off of?

Re: Running PD Board from an outlet
 

Decide how much power the motor takes. Worst case for a CIM on a 40A fuse is going to be 12V*40A = 480W coming from the power supply. Add up all the motors you want to use to get a worst-case idea.

with a 500W power supply, you can test 1-2 motors at a time under full load. If your wheels are not on the ground, they are not at full load, so maybe you can run 4 motors or so.

Re: Running PD Board from an outlet
 

For a full robot on the ground? Somewhere in the range of 2-6kW.

For testing subsystems while up on blocks? 1kW might do it.

Actually, a CIM can easily draw 100-130 Amps at stall depending on wiring. When a breaker has a 40 Amp rating, it means that it can sustain 40 Amps indefinitely.



EDIT to add:
Regenerative breaking can play havoc with some power supplies. Where a battery would simply accept the regenerated charge, some power supplies will go high-impedence to protect themself. The voltage can spike and destroy the supply or the robot electronics.

Re: Running PD Board from an outlet
 

For just powering the electronics, a small 12 volt power supply will work. I imagine you could dig one out of an old computer.

To survive a regional you are going to need lots of batteries and an extra charger. So buying that now would be a good idea. If you are not running motors or running them lightly loaded, the robot battery lasts a long time.

Re: Running PD Board from an outlet
 

I second the computer power supply. Ask your school's tech department if you can get a power supply out of a dead computer. Those can easily put out a huge amount of clean current (I currently use one to drive the stereo in my school's NOC).

A word of warning though, those can put out dangerous amounts of current, make sure you know what you're doing when working with it.

Re: Running PD Board from an outlet
 

I've used a car battery charger to power a minimal control system (digital sidecar, cRIO, camera, single motor) through a power distribution board. I'm guessing this power isn't much cleaner than that from the car adapter. Does the dirty power permanently damage parts or is it simply unreliable?

I have also used a PC power supply to power the newer cRIO directly (accepts as few as 9 volts) but have not attempted to power anything through the PDB.

Re: Running PD Board from an outlet
 

They can also retain lethal voltages, with all their capacitors and what not, even when unplugged. Don't ever open a computer power supply!! ::safety::

Re: Running PD Board from an outlet
 

You do know the battery will put out a lot more current than your typical power supply? Even with big capacitors? :eek: But you point is well taken.

If you use a car charger, keep the battery connected as well. It will clean up the charger's dirty power. Just do not use a charger that has a start the car mode.

Re: Running PD Board from an outlet
 

I recently measured our control board at .9A drawn during motor idle period. Aboard are the usual suspects and 6 jaguars. To this you would have to add the motor currents as noted above. Connecting some other source of 12vDC could be done, but as you can tell from the comments, this designation covers a lot of supply waveforms and reactions by the supply.

The other thing you should consider is getting some additional energy supply gear for your team. Perhaps you already have it, and were only talking about powering the board during a home-based session. We've done this too. You have to be very careful not to discharge the legal batteries too deeply. They can be damaged by it. Be sure to search CD for more discussion of battery and electrical practices.

Re: Running PD Board from an outlet
 

Everyone,
Motors can produce significant currents at start up. My 35 amp linear supply will go into over current protect on an FP motor. Not only does the supply need to be able to handle large currents, it must also be able to handle startup current and be low impedance. You might find one cheap but in general, the cost for a line operated supply is likely too costly for most teams. Most inexpensive car chargers simply put raw rectified current into a battery. This is pulsed at power line frequency and could be either halfwave or fullwave rectified power. Even a battery connected across the charger will not take care of all the transients. Bench supplies can be had to run the PD and Crio along with controllers and relays as long as there is no load on these devices. Any CB power supply available at Radio Shack will likely be able to handle the current. I have a 5 amp supply at home that we have used from time to time.
As to computer power supplies and most switchmode, line operated supplies...
These devices generally rectify the incoming line voltage giving them a ~160 volt primary power supply. It is the capacitors in this part of the supply that carry the high voltage warning. The caps across the low voltage supplies are generally small in comparison and only carry the rated voltage (+/-12, +/-5).

Re: Running PD Board from an outlet
 

If you are running motors at anything besides completely unloaded, you are better off using a battery. I was thinking more of ways to power just the electronics.