LiPo battery: safe connection to Arduino

Other Hardware General Electronics
1

Hi,
a basic question:
I'm succesfully powering my Arduino Nano with a LiPo rechargable battery (11.1 V).

connecting battery positive to VIN, and negative to GND.
11.1 V is needed because of part of the circuit (a 12 V led strip, not shown in the figure).

I was wondering if it is safe to connect the USB
cable too, for serial monitoring.
Are the two power supplies mutually excluding?
Should I add some protection component to my circuit?
Thanks

ps: I already connect the USB cable and everything works, but I want to be sure
the circuit is ok and safe

2

The two supplies are indeed mutually excluding - the 11V on Vin will disconnect the USB 5V.

Make sure you have a fuse if the LiPo is of any size, then if something shorts the fuse blows
rather than all your wiring catching fire or melting.