user29658: I have USB charger battery pack with two output ports (Fremo C510).  One is marked as 5 volts 1 amp, and the other as 5 volts 2 amps.
I'm building a toy robot and would like to run the UNO off of one of those ports, and the motors off of the other.
Can I safely do that?  I have two main concerns:

Can I safely power the arduino with that current?
If I power both the motors and the arduino from that source (two usb ports connected to the same battery), will I still have to worry about spikes from switching the motors on and off?  I don't know how those ports are wired to the actual battery inside.


user313: You can power the Arduino from either side, since it will only draw what it needs, and most arduinos are powered from a .5 amp USB port. But you'll want to reserve the higher current side for the motors.
Make sure your motors' total draw (including starting current) doesn't exceed the 2 amps available.
Unless you can find out for sure that the two power ports are isolated from one another, you're better off to assume they are not and provide motor spike damping yourself.

29658: <p>I have USB charger battery pack with two output ports (<a href="https://www.newegg.ca/Product/Product.aspx?Item=N82E16875790001" rel="nofollow noreferrer">Fremo C510</a>).  One is marked as 5 volts 1 amp, and the other as 5 volts 2 amps.</p>

<p>I'm building a toy robot and would like to run the UNO off of one of those ports, and the motors off of the other.</p>

<p>Can I safely do that?  I have two main concerns:</p>

<ul>
<li>Can I safely power the arduino with that current?</li>
<li>If I power both the motors and the arduino from that source (two usb ports connected to the same battery), will I still have to worry about spikes from switching the motors on and off?  I don't know how those ports are wired to the actual battery inside.</li>
</ul>
 313: <p>You can power the Arduino from either side, since it will only draw what it needs, and most arduinos are powered from a .5 amp USB port. But you'll want to reserve the higher current side for the motors.</p>

<p>Make sure your motors' total draw (including starting current) doesn't exceed the 2 amps available.</p>

<p>Unless you can find out for sure that the two power ports are isolated from one another, you're better off to assume they are not and provide motor spike damping yourself.</p>
