This breakout board will solve all your power-monitoring problems. Instead of struggling with two multimeters, you can just use the handy INA219 chip on this breakout to both measure both the high side voltage and DC current draw over I2C with ±1% precision.

Specifications:

• 0.1 ohm 1% 2W current sense resistor
• Up to +26V target voltage
• Up to ±3.2A current measurement, with ±0.8mA resolution
• Product Dimensions: 25.6mm x 20.4mm x 4.7mm / 1.0″ x 0.8″ x 0.2″