Reading on Matson battery monitor

[landoman]

Fitted a Matson Bluetooth battery monitor to my 110 auxiliary battery ( Optima yellow top )
.....loaded up the app ...BM2 ......a tad confused about the readings I'm getting
....says

12.36 V / 44%
12.53 v / 36% ( after running the engine for a while)

BUT ....I have a chart for various charge levels on an AGM battery .....
12.3V =70% charged
12.5V. = 80% charged

SO ....is the Matson telling me how much charge needs still to go in to the battery based on the voltage versus the chart which is telling me how much charge is in the battery based on the voltage .......

[Tombie]

I’ve read similar reports of other units doing similar strange things...