Battery values & percent shows weird values Vib Sensor V3 in Node-Red

I have a vibration sensor V3, feed with 12 VDC external power supply. I have seen two issues that I can’t explain on battery reading from Node-Red:
1- In node-red, using external power supply 12 VDC, shows battery value = 3.14, and 82.68% on battery percent, it is little bit weird, I expected higher battery value and 100%. Also I tried power it with batteries, disconnect external power, and moved the switch toward the enclosure wall, and it says 3.2844, which higher than external power supply, and still it is not a number that I expected. This sensor has a brand new 6 AA batteries.
2-It called my attention that says 82.68%, which means the equivalent 100% voltage should be 3.799, but this sensor is using 6 AA batteries => 6 * 1.5 V=9V. Where that 100% came from.
3-I tried just parsing as per Manual mapping, and shows same values from Node-Red.

Battery actual voltage is 3.6 when they are new.
External power outputs 3.3V all the time.

Battery actual voltage is 3.6V, and how it is related with 6 AA Batteries installed?. In other words, how can we explain to the end customer that Battery value of 3.24 reading, what does it means in terms of actual AA installed.
External power outputs is 3.3V internally, maybe using a regulator chip. It called my attention with 12 VDC, should not be already near max voltage 3.3V, and actual value is 3.14, less than with batteries.
I understand from design point of view your numbers, but how to explain or interpreting for the real application the battery value numbers in both cases? Is it a little bit confusing to me because it is more related with the voltage at the regulator, not from actual power source. For example, if reading 3.14 with external power source what does it means, 87%. However when I read with multimeter we are feeding with 12.1 VDC. Is it something wrong with power supply? Why reading 3.14? Or it has 6 AA new batteries (~9VDC) what means 3.24 VDC, in terms of user?
The other thing is that the number doesn’t match regarding the %. For instance, 3.14 in Node-Red, says is 87%. If we do the math for 100% can see, what the value should be.

There are two circuits that manage power, external and battery. They are isolated and not related to each other in any way. The sensor is switchable between the two circuits, the sensor is compatible with both voltage levels and provides readings for whatever circuit is in use. The batteries are NOT strictly in series, they are arranged in 3 sets of 2 for longer battery life. This is why you will not see a 9V reading on the batteries.

@reyan You mentioned 9V a few times. All of the batteries are not in series.
Rather there are pairs of Series (each AA is 1.7V nominal x2 = 3.4 nominal) and then those are all in Parallel to add the capacities.

That is why the unit can run on a single pair of AA, as long as they are next to eachother in battery holders, and the voltage will still appear as 3.4, but it just wont last as many transmissions. Add the other 4 batteries, and you might change voltage slightly, but you will greatly increase capacity.

I think you need to double check your reasoning for ‘6 AA batteries => 6 * 1.5 V=9V’ as that is not how they are wired, as far as I know.

I am not NCD, I am just another heavy user of these Vib Sensor V3 units.

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OK, thanks for explanation. I understand better now.