This is a quality Watt Meter and Power Analyzer that is a great addition to your RC tools.

This 130A watt meter is a very accurate R/C amp/watt meter.

You can use this product to:
Predict model airplane flight time with any given propeller.
Ensure peak currents are safe for motor, ESC, wiring and connectors.
Check battery health and performance.
Evaluate R/C battery charging efficiency.
Choose the best propeller or gearing and the most efficient motor.
Check for wiring and connector power losses.
Measure power and energy consumption of ANY device with a battery.

Specifications:

Operates without auxiliary battery from 4.8 to 60V or with an optional auxiliary battery

Measures 0 to 130A, resolution 0.01A
0 to 60V, resolution 0.01A
0 to 7800W, resolution 0.1W
0 to 99Ah, resolution 0.001Ah
0 to 9999.9Wh, resolution 0.1Wh