I recently bought a little raspberry pi + freenove car kit. The kits instructions are to use two 3.7 V 18650 rechargeable batteries. I have these batteries and everything works fine.

But now I'd like to power the board from a wall outlet instead of using batteries.

The freenove manual says that the shield uses 5.6~11V DC power supply. "If the power supply is beyond this voltage range, it may cause damage to Shield."

enter image description here

I have an AC converter that says it converts AC current to 9V/1A. Here is a link to the convertor on amazon. It seems like this would work as it is between the 5.6V and 11V range, but I wanted to make sure so I didn't destroy the board.

The only other concern I had was that the shield then distributes this power to two voltage regulation systems, both of which are 5V/3A (see the picture below)

enter image description here

If the AC/DC converter is only providing 1amp, I wonder if the regulators will have difficulty providing the 3amps needed by the raspberry.

To me it seems like there wouldn't be enough overall power

9v x 1a = 9w but 5v x 3a = 15w

(i'm still learning about amps, volts, etc, so I might be confused here. Any gentle clarification would be very much appreciated :)

1 Answer 1


Your calculation is correct.

1 amp @ 9 V is 9 watts

3 amps @ 5 V is 15 watts

You need a bigger power supply. Remember that converting power is not perfect. I would assume that there will be something like a 20 % power loss in going between 9 V and 5 V.

  • You probably mean 80% efficiency (20% power loss). Aug 30, 2021 at 9:22
  • When I was a kid, we were lucky to have only an 80% power loss. :)
    – NomadMaker
    Aug 25 at 21:15

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