Powering Solenoid + Nano with Lipo

[xaphor123]

I've got a project that uses a 12v solenoid and a nano, I've figured out the direct project wiring itself, (Using a TIP120 basically as a relay) but was wondering if I can use the battery to power the arduino and the solenoid.

I'll be using an 11.1v lipo (Or maybe a 7.4v)

I've heard using the onboard step down isn't very efficient and uses a lot of heat so was thinking would the battery into a buck converter into the Arduino work?

I'm thinking I'll wire it to the buck converter then solder off them points to the circuit/solenoid.

Will I need some sort of battery protection for the lipo? If so please can you suggest?

Alternatively I could power the arduino seperately with an 18650 1/2 of them, but I'm trying to keep this project as compact as possible

[jremington]

A 5V step down converter will work to power an Arduino Classic Nano, through the 5V pin. I recommend this one.

However, you must add a flyback diode across the solenoid windings to protect the rest of the circuitry from the very large voltages generated when the solenoid is turned off. The circuit below shows a motor, but gives the general idea: