I am working on a concept idea at the moment that I would like to take forward later in the form of wearable computers. At the moment, I am using a Raspberry Pi as the computer itself.
It presently is fairly simple. There are WiFi and Bluetooth Adapters connected, as well as a small shield connected to the GPIO for some status LEDs, the whole lot using very little power. I am unsure of specifics, but a 1A 5v power supply runs it pretty well.
But that requires it to be plugged into the mains, which is not so good for wearable computers.
So, I am presently designing the power system. The concept is simple. 4 parallel sets of power source modules. Each power source module is comprised of 3 AAA (and rechargeable) batteries, as well as an internal circuit to determine how much current each module has available, the operating temperature, battery lifetime, and provide some control functionality.
Ideally, the system will determine which module is running low, throw a warning for a user to replace the battery, and disable it (allowing it to be removed and placed on charge).
question 1) Will 3 AAA (each at 1.5v, totaling 4.5v out) provide enough voltage to power up the Pi and its Peripherals? Or will I need to beef it up a bit further? (I have gotten a Pi with a few peripherals to run on 3 batteries, but they felt a little warm after about 15 minutes)
question 2) Can a power system that is designed with a "hot swap" like power module function be safe to operate (very low voltages), and allow for effective continuous operation of a pi module?