[beagleboard] Nubie questions

Hi, sounds like an interesting project. I don’t know of any off hand but I’m sure you could do some googling to find others like it.

Is this going to be a aerial vehicle or land based? Because, and I’m not an expert, I would think that the motors would draw significantly more power than the beaglebone board. This would make the motors your limiting factor for usage time. You can probably calculate some upper bound on power consumption of the beaglebone by looking at the max power draw of the on board power regulator. Batteries or wall adapter, cape or none, the board will not deliver more power than the power regulator chip will handle.

Also, for any vehicle I would recommend using at lithium ion rechargeable battery pack instead of off the shelf AA batteries. Lion batteries have much higher engery density, meaning per unit weight they have more storage capacity. Lighter and delivering more power is a good thing.

good luck!

Thanks a lot Brian.

It’s a flying thing and the mission would be to automatically fly to the desired location, take photos and return back. The motors can run up to 28-30mins according to my calculation. Anyway I think I’ll wire the battery cape to my 4400maH rechargeable batteries, which power pretty much anything on the device. Thanks a lot again :slight_smile:

A couple of things to think about in your design:

#1 Since you’ll have motors running, be wary of noise impacting the power feed to your Beagle. I’m not exactly sure how the motors would impact the power supply, but DC motors, with their brushes, etc. can be very noisy on a power line. It might be wise to have a separate set of batteries for the Beagle that do not supply the main motor (and / or a lot of filtering circuitry) to avoid transient noise causing the beagle to reset due to a voltage spike. (Not a fun thing to deal with. I dealt with many issues in the auto industry in this regards.)

#2 In terms of power usage, you can easily measure this with an appropriate power supply. A good, benchtop power supply will give you the exact output current of the supply. By measuring this and multiplying it by the voltage, you can get the power, etc. It may not be constant, but with a bit of testing you should be able to get something useful.

#3 I can’t say for certain, but I’d be wary of a 3G cape, as that level of radio transmission tends to eat power up. Think of your cell phone, how long it lasts if data is turned off, and how long it lasts if data is one.