The backboard probably states 3.6 - 6v quite clearly, thereby strongly implying that 3.7v is sufficient but 2x3.7 is probably too much. I don't suppose a coin cell has enough power to run an HC-05.
The backboard probably states 3.6 - 6v quite clearly, thereby strongly implying that 3.7v is sufficient but 2x3.7 is probably too much. I don't suppose a coin cell has enough power to run an HC-05.