Powering Arduino and Motor Shield

Projects General Guidance
1

Apologies if this has been asked numerous times.

I am a bit confused with powering the Arduino and a motorshield (Adafruit Motorshield V2). I have 4 18650 Lithium batteries. This results in 4 X 3.7 = 14.8 V.

Reading the Adafruit information, it says to power the shield seperately. So does this mean I use my 14.8 V for the shield and then use 9V for the Arduino? Thus needing 2 power supplies?

However looking at projects online, it seems like people only use 1 power supply.

Is there some "Source of truth" which can point me in a well known powering setup.

I have 2 6V DC Motors.

I am stuck between using a motorshield and arduino or buying the Elegoo smart car robot kit, to move further in my learning of the Arduino. Ideally I would rather figure this power setup than use a pre-existing kit.

2

You can use a stepdown converter to power the Arduino from the motor power supply. The simplest option is to use one of these 5V converters or similar, and connect the 5V output to the 5V Arduino pin. There are also 7 to 9 V versions of such regulators that could be connected to Arduino RAW or Vin.

Don't forget to connect all the grounds.

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3

From Adafruits page:
"Polarity protected 2-pin terminal block and jumper to connect external power, for separate logic/motor supplies"

You can power both Arduino + the shield with motors from one source, but motors generate noise, and you might need to filter that out. It's all in the FAQ.

4

Thanks, I had that in mind as well but forgot.

5

Nominal. But 17V when those batteries are fully charged.
And that shield is rated at 13.5V.
And your motors at 6V.
You have to find power supply / battery that fits the specs of your motor.

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6

Thanks, that looks like a solution.

7

Thanks for pointing that out.

8

Thanks to those who responded @kmin @jremington @ledsyn and saved me ordering parts that would not of been compatible. I believe I have a solution now.

Screenshot 2025-02-22 162343
Screenshot 2025-02-22 1623431523×680 24.2 KB

For the Motorshield, the official Arduino motorshield
Then two step down converters

https://uk.robotshop.com/products/step-down-dc-dc-power-converter-25w?qd=5376ce529ea1b16be04eb5984c44b2ac

One will provide power for the Arduino (I have selected 10V because it sits between the recommended 7 - 12V).
The other for the motor shield.

Thanks for your assistance, this is new to me.

9

Why use 4x18650 batteries in series when you could use just 2, thereby avoiding both converters?

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10

Thats actually an obvious solution. Thanks.

Probably silly question, will 6V motors be OK with this, as it is still slightly higher. The Arduino says 7 - 12V, so it will be fine.

11

Brushed DC motor voltage ratings are nominal, not absolute maximum.

A general rule is that the higher the motor driving voltage, the shorter the motor lifetime.

12

Post the specs of your motors. Or link.

13
14

There's no max voltage given, neither datasheet.
Some vendors (like Mouser) are selling it as 9V motor though...
You could contact your vendor and ask max voltage.

1 Like
15

Thanks, I will get in touch and see what they say.

Again, thanks for the help. Much appreciated.