Thor Forums

[FW28z]

I tested the monitor by connecting one channel and using a coffee cup with water to dip the probes into. I then measured the RED wire on the harness, which is the "sense" wire going to the monitor.

Button not depressed = stray voltage under 0.02VDC
All sensors out of the water = 8.6VDC - 1 LED lit.
Ground sensor only in water = 8.6VDC - 1 LED lit.
Yellow and Ground sensor (1/3) = 6.8VDC - 2 LED lit.
Yellow, Green, and Ground sensor (2/3) = 5.2VDC - 3 LED lit.
All sensors in water (FULL) = 1.3VDC - 4 LED lit.

Minimum current (no button pressed) = 0mA
Max current (button pressed 4 LEDs on) =31mA

I have no idea why there is such a change in linearity with all sensors in the water. Of course, it is because the unequal resistor values of the harness - but why was it necessary to do that. I suspect the answer lies in the configuration of the resistor ladder reference inputs to the comparators.

So more examination...

Also, it appears that there is no current drawn from the battery until you depress the switch. I think that powering down the capacitive sensor between readings will be the hardest thing to do. The existing resistor harness is passive, and any capacitive detection will be active.

But if the capacitive sensor could be made to operate in the uA range, then the coach battery's self-discharge rate would be higher, and such a small load would be insignificant.