Match the meter

The new voltage scale is the old scale times the meter voltage, divided by the voltage the board is reporting, then rounded. It is clamped from 10 to 255. The demo starts at 110, with divider 10 and multiplier 1. Divider and multiplier each run from 1 to 255, and the helper does not change them.

The picture uses that sum and nothing else. Drag the meter. At 16.0 V the scale stays 110 and the lamp says it matches. At 16.8 V the scale becomes 116 and the lamp says to raise it. At 15.2 V it becomes 105 and the lamp says to lower it. A worked case of scale 250, a board at 10 V and a meter at 20 V, rounds past the top and stops at 255.

The voltage card footer says to measure the battery and raise the scale if the reading is low. A board at 16.00 V and a meter at 16.8 V is that case: the board is low, so the scale goes up. Compare them at rest, on the balance lead, before you arm. Sag under load is the pack, not a reason to chase the scale.

Under 0.5 V on either side, the helper returns no scale and the note says to plug in a battery first. Applying when the numbers already agree says the readings already match.

An ADC current scale is labelled mV/10A, and the offset is millivolts. The demo ADC meter starts at scale 400 and offset 0. For that meter the reading shrinks as the scale grows, so the new scale is the old one times the board amps divided by the clamp amps.

Board 12 A and clamp 10 A moves 400 to 480. The board was reading high, so the scale goes up and the next reading comes down. Board 10 A and clamp 12 A moves 400 to 333. Either current under 0.1 A is refused. The note says to draw at least a few amps, and to spin the motors with the props off, first.

A virtual meter is different. Its scale is labelled mA/throttle and its offset is milliamps. The new scale is the old one times the measured amps minus the offset, divided by the reported amps minus the offset. Scale 100, offset 1000 mA, a board at 11 A and a meter at 21 A, becomes 200. The demo virtual meter itself starts at scale 0 and offset 0. That 100 is a worked example of the sum, not the number the demo opens on.

The helper only adjusts the meter that matches the current source, and only when that meter is ADC or virtual. Any other source gets the note to choose an ADC or virtual current meter first. The current page for sources is the battery guide. Change the source and expect to calibrate again.

The calibration card is on the Power tab when the board has a voltage meter. Open it, and the dialog shows the live volts and amps once they arrive. Until they do, it says it is waiting for the flight controller. Enter the meter voltage, and the clamp current if you have one. Apply writes the new scales into the draft.

The note names the old scale and the new one, then says to save to keep it. Closing the dialog without a change, when the readings already agree, says they match. Nothing is stored until you save on the Power tab.

Leave the cell warning alone while you do this. A warning that was changed to hide a bad scale will fire at the wrong pack once the scale is honest. The battery page is where those warning voltages and the capacity live.

A preset can overwrite a scale you just saved. After a preset, read the diff. If the scale moved and the meter no longer agrees, put your scale back and save again.

Open Power on a Betaflight board and choose Calibrate voltage and current. Chrome or Edge connects over USB or Bluetooth. Android adds Wi-Fi. iPhone uses Bluetooth or Wi-Fi and has no USB host.

This sum is the Betaflight meter. INAV keeps its own voltage scale. Do not paste 110 into an INAV field and expect 16.00 V. Props stay off if you spin the motors to raise the current for the clamp.