# Same lipo power source for raspberry pi and motor hat

I am building a rover and would like to power the Raspberry Pi and the Motor HAT with the same power source.

I want to use a 2500 mAh LiPo battery for a long play time. My DC motors work at 6V-9V.

How can I do this?

• Can you add some more details to your question? For example, which Pi? Which hat? Which motors? What other electronics will be drawing power from this battery? Commented Nov 2, 2017 at 2:48

You will quickly face 2 problems : voltage and current.

Voltage You battery produce 3.7V, the Raspberry use 5V, your motor 6-9V. You will basically needs two DC-DC step-up voltage converter to produce 5V and 9V from 3.7V.

Current Now let's look if your supply provide enough current : The raspberry pi3 needs 2.5A at 5V and the converter is said to have a 95% efficiency.

`0.95*(Ubat*Ibat)=Upi*Ipi`
`0.95*(3.7*2.5)=5*Ipi`
`Ipi=1.7575 A`

We can see that one battery is already not powerful enough for the raspberry (1.75A instead of 2.5A), so powering a motor on the same battery won't just work.

I don't know how other people solve this case, but you can look for lighter hardware that would limit the need of power (arduino ? rpi zero w?), or for bigger batteries.

• The Lipo Battery is 11.1v Commented Dec 30, 2017 at 1:30

Personally I would just use a UBEC and drive the Pi and the motors from the same 5V supply. A UBEC converts a voltage in the range 6V to 26V to typically 5V and is what a lot of model airplane and quadcopter enthusiasts use. Your motors should work from 5V.

• Union of Banana Exporting Countries (UBEC) FTW. That was DuckDuckGo's Wikipedia first result. Maybe a brief explanation of what you mean by UBEC, what it is, and how you might use it in this case? Commented Nov 2, 2017 at 2:47
• @YetAnotherRandomUser I understand your reasoning but am not minded to make a change. Anyone who does not find the intended definition should not be using electricity!
– joan
Commented Nov 2, 2017 at 6:32