One of the biggest reasons I love the RedRotor RROSD is that its current sensor comes pre-calibrated. But there are lots of great OSD options out there that require you to manually calibrate the current sensor. If you've got one of them, here's how to get it reading accurately.
Thanks to Furious FPV for providing the Kombini that I'm using to do this calibration. However this approach will work for cleanflight, betaflight, MWOSD, or any other similar current sensor.