I'm working on a mobile computer unit with a Raspberry PI 3 motherboard. The computer unit needs to run on battery so i can bring it with me anywhere. I'm going to solder both the battery pack and power supply (buck or buck boost) myself, since it need to fit as perfect as possible in a custom made 3D printed case.
I have decided to use LiPePO4 battery cells, either 2 (6.4VDC) or 3 cells (9.6VDC), I guess 3S is best since I only need a buck converter to get 5V contra 2S that may need buck boost. I'm thinking of soldering a) power supply and b) cut of (high voltage/low voltage) on the same PCB.
But I'm not so very experienced with electronics other than I have some basic electronic education, so I'm wondered if someone has some advice or inputs to this project. I have mainly three questions.
- Is it better to use 2S or 3S battery to this project, I'm then thinking of efficiency of power supply, as far as I understand 6.4VDC is closer to Vout (5VDC) so it will be a more efficient power supply than Vin as 9.6VDC. Runtime is importent, so more efficiency power supply is longer runtime.
- I'm looking for power supply circuits that can deliver 2-3A, is it enough to run just the RPI 3 board?
- I have found several DC/DC converters that delivers 2A@5VDC, but these use Linear Technology IC that are pretty expensive, I have been told multiple times that LT's IC is overrated, what other IC brand can I search for?
And if you guys have been doing similar projects with RPI 3, or have other advice, please inform me.