Power Issue USB vs. Battery Power

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CPARKTX
 
Posts: 11
Joined: Mon May 12, 2014 6:13 pm

Power Issue USB vs. Battery Power

Post by CPARKTX »

I am having a strange problem and need guidance on what may be causing this. I have a project powered by an Arduino Mega; when I supply power via USB from my computer, it works great (even my very old Mac which I believe has lower voltage USB). When I power via battery through DC barrel jack, the LCD is hard to read and the ping sensors don't operate properly. Clearly there is a power issue, but I don't know what or why. For batteries, I am using fresh AA's in a 6 x AA = 9v which is well within the input range listed for the Mega. (I've also tried a single 9v battery through the DC barrel jack, same bad result).

I am using completely separate power supplies for the rest of the project...I run a separate supply to the Adafruit Motor Shield, and a third power supply to power the servo (common ground on that one).

Any suggestions?? Anything I can measure/test as far as voltages (with correct circuit)?

Thank you for any ideas.

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Franklin97355
 
Posts: 23912
Joined: Mon Apr 21, 2008 2:33 pm

Re: Power Issue USB vs. Battery Power

Post by Franklin97355 »

Several things. Do you have grounds tied between all the parts and have you tried a 6 to 12 volt wall power supply yet? You can check the battery voltage at the batteries when it is running, there may be a sag in the power available.

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