Advice on battery power supply for project: pi, arduino, 2 servos


I am building a project which will run on battery power and am seeking advice on what specific supplies I should use.

The project consists of:

–Raspberry Pi 3 Model B
5V micro-USB
Recommended PSU current capacity: 2.5A
Max total USB peripheral current draw: 1.2A
Typical bare-board active current consumption: 400mA

which runs an

–Arduino Uno
[or power jack, 7-12V]

which in turn runs

TWO servos
—HSR-2645CRH servo
Voltage range: 4.8 - 7.4 V

I am new to electronics but have the advice that the servos should be on a separate power source than the pi and the arduino, and that all parts (pi, arduino, servos, two batteries) should all have a common ground.

Do you have advice on what I should use to power this system? I would like it to run as long as possible–hopefully at least 6 hours and optimally 12 or more hours.

Thanks in advance!


We do not have any specific advice for your battery packs, but you might find this blog post helpful in calculating your system’s needs for your 6-12 hour run time.

In general, we expect LiPo battery packs to be the best for high current draw applications, especially where light weight is preferred, but you might also consider a lead acid battery for that kind of extended run time.

It should be fine to run your system off of multiple power supplies as long as you have a common ground as you mentioned. Additionally, you might consider using voltage regulators connected to a single battery to get the different voltage level requirements of your devices.


I think I have a solution which uses power supply battery packs, but has a kludg-y approach…is there anything wrong with modifying the cables from battery supplies to add a ground which would go to the common ground? A diagram is below with the question more specifically in blue. I’d like to use the battery packs as I can set it up to be able to fairly easily swap them out with only minor interruption for the long runtime I’m hoping for.

( image also here: Dropbox - power-q-4.PNG - Simplify your life )

Your power supply to the Raspberry Pi and Arduino is probably fine. Please note, you only need one connection to create a common ground to your servos, so your USB splice and Arduino ground connections to the ground rail are not needed (you already have those connections through the Raspberry Pi and its USB cables).

Breadboard connections like you show are typically not recommended for currents as high as your servos might draw, so I recommend making those connections more directly. Additionally, your regulator is probably too small for the potential current draw of those servos (probably in excess of 1A each), so you should check on their current draw and get an appropriate regulator and possibly a higher current power supply if necessary.