Powering Motors

I am trying to use my Arduino Uno to control an OWI Robotic Arm Edge, and was wondering whether I could power the Arduino+2 Stacked Adafruit Motor shields using a portable USB charger, rated for 5.17V(which I measured with a multimeter) at 2.1A and 1.0A. I would need to be controlling 5 Hobby sized DC motors. It is a 12,000mAh battery, and I was also wondering how long it would last.

Ideally you should have a separate power supply for the Arduino so that the current drawn by the motors cannot interfere with it by drawing down the voltage.

A lot depends on how much current is required at any instant. Motors can draw heavy currents at startup or if they are stalled by a heavy load. Then there is the question of how many motors draw current at the same time. Running directly from batteries that don't need a regulator would be better.

As to duration - I think there is no way to predict that without experiment. Battery manufacturers routinely overstate the capacity. Assume its real capacity is only 50% of the sticker capacity. And regularly "emptying" the battery will shorten its life. Don't leave it in a discharged state if you are not using it.

...R

am trying to use my Arduino Uno to control an OWI Robotic Arm Edge, and was wondering whether I could power the Arduino+2 Stacked Adafruit Motor shields

[u]This[/u]? That shouldn't need motor drivers (shields). In fact, servo motors have built-in drivers so you just provide power and a pulse to determine the angle. I'm assuming it has servos, but in any case if it needs any motor drivers, they must already be built-in...

Or, you can use relays driven by the Arduino to replace the manual switches.

rated for 5.17V(which I measured with a multimeter) at 2.1A and 1.0A. I would need to be controlling 5 Hobby sized DC motors.

What is the rating on the motors?

Is that power supply made to work with the robot arm, or is it just some random power supply you happen to have?

at 2.1A and 1.0A.

What does that mean??? Is it 2.1A or 1A? Is that measured current or rated maximum current?

It is a 12,000mAh battery, and I was also wondering how long it would last.

12,000mAhr is 12 Amp-hours. That means the battery will last 12 hours at 1 Amp or 6 Hours at 2 Amps, etc.

I believe the amp-hour rating is when the battery is down to 80% of it's rated voltage. So for example, a 6V / 12Ahr battery will be down to 4.7V after delivering 1A for 12 hours.

Thank you all who replied. I have it working now.