Leaving USB-Serial cable connected while powering from battery pack

Projects Networking, Protocols, and Devices
1

I need to leave the USB-Serial cable connected to the MEGA while I test a sketch that uses a SIM900 GSM/GPRS module.

I would like to connect the battery pack to the MEGA which should provide enough current for the SIM900 to work according to specs.

My questions are:

Q1/ If I connect the battery pack to the MEGA and leave the USB-Serial connected to it into order to watch the output in the Serial Monitor, there won't be a power issue since the MEGA is getting power from the USB and the battery pack?

Q2/ Will the MEGA actually use the power from the USB or from the battery pack? Or will it actually use the power from the USB and draw any extra power from the battery pack as needed?

Thanks

2

The MEGA will use the auto-power select function and will probably power off the battery pack.

3

OK. I thought that anything that needs to be powered from the battery pack via the Barrel Jack, needs to be plugged into the Vin pin?

4

Yes. The Vin pin is directly connected to the barrel jack. (well, maybe thru a diode)

5

There is definitely a diode between the barrel jack and Vin.