INA219 I²C Power Monitor

Drop a tiny shunt in series with a battery and read out live volts, milliamps, and watts over I²C — perfect for sizing a project's power budget.

Difficulty: Breadboard. Estimated build time: about 35 minutes. Estimated parts cost: about US$5.00. 6-part bill of materials with live supplier pricing. A bench instrument that watches the current and voltage going to a load and reports them in real time.