Battery charge inconsistency between voltmeter and Metr Pro

I’m using this battery meter properly configured for my LiPo 6S 4Ah to monitor my battery levels (it has a rear button to configure the battery type and the cell in series).

Few days ago I installed and configured the Metr Pro module, now I read two really different values of battery percentage. What’s the problem here?

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If I had to guess I’d say the feebay meter is simply going by the state of charge (SOC) and determining the remaining capacity based on voltage. While the Metr Pro is more likely figuring battery percentages based on a number of factors like average current draw and amp hours used.

Based on a quick search I’d sooner trust the Metr Pro rather than a cheap feebay voltmeter.

Could be wrong though as I have no experience with either of those items.


My cheap lcd meter says different readings than the focbox UI app as well. I suspect the on board reading is more reliable.


Metr pro has it’s own way of telling the percentage left. If you go back into the settings and battery, you can choose between liion, lipo etc. If you go with custom you can set what voltage should show what percentage.

with 3.1v at 10s the battery obviously isn’t at 0% since you can go down to 2.9v etc. Thats how you can set the percentage however you want.


Me too. atm with no reason I would trust Metr Pro more than the cheap battery meter but however I’d like to understand what’s going on :eyes:

What do you mean by “on board reading” ?

Oh! I had not yet clicked the “custom” option…

Given that the VESC can’t read the voltage of the individual cells (unless through a BMS) it will assume the percentage of the entire package by reading only the first cell which usually measures a higher voltage than the others. This seems like a fragile estimation, I’m wrong?

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Yes; the VESC reads the entire pack voltage only if you don’t have it integrated with a BMS.

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Ok, I think I figured out how it works.

I just tried to switch the Battery type option between Li-Po and Custom and see if the battery percentage change based on the option. Yes it does.

If you set Li-Po, the VESC read the entire pack voltage and estimate the remaining capacity based on a preset discharge voltage curve.

Instead, with Custom the VESC calculates the voltage of a single cell with a simple mean dividing the entire pack voltage by the number of cells set. So using the thresholds “Cell voltage at X%” it will estimate the remaining capacity of the battery.

In this way it’s possible to modify the percentage shown as desired to match the lcd battery meter.