I built a 22V battery pack with 6 18650 cells connected them to a 6s BMS. I will use this to power a portable audio amplifier.
I also want to use the same battery pack to power a Raspberry Pi Zero W embedded in the device.
According to the specs, the Zero W has a typical / max current draw of 150mA / 1.2A.
My idea is to connect the second tap (7.4V) with a resistor and the B- on the BMS to the RPi 5V USB input.
I have two questions:
Will this work? Is the BMS designed to be used this way, drawing the full 22.2V from the whole array and 5V from only 2 batteries?
In calculating the voltage drop resistor for the 7.4 → 5V conversion, which current draw shall I use? The max. rated 1.2A?
Thanks in advance.