Power supply to Zumo

Hi. I’ve just built a Zumo with zumo shield and sensor board, and had a successful first test. To program the Uno, I kept the batteries switched off and took power from the USB connection. To drive, I disconnected the USB then switched on the batteries. My question: is it ok to have a USB link when the battery switch is on? Two simultaneous power supplies? [I’d like to use the serial link for debugging.]
Thanks
Max

Hello, Max.

Having both the VIN and USB connected on the Zumo shield should be as safe as powering the Arduino through both the barrel jack and USB connector. For more information about this please see this forum post.

- Grant

So - if I understand the final posting in the linked thread correctly - you recommend against, because there might be some risk to the PC into which the Arduino is plugged?

Thanks

Max

That is correct, we do not recommend supplying power to the Arduino from both an external power supply and USB. However, we have not heard of anyone having an issue because of doing this.

- Grant