Relative to this thread -- just how much power does the Interstate 12V
"Coach" system draw when not in use?
I added a net battery current monitor when I upgraded the solar system. The measured standby current draw on my rig is -0.4 Amps. It does not seem to vary if I have the coach battery switch on or off. The only thing I can determine that goes off is the propane gas detector that only draws a specified 70mA (0.07 Amps).
To confirm this I researched each component on the 12V Coach side and came up with a max calculated load of 0.5 Amps. I had to estimate a few components since I couldn't find the exact values. But anything with electronics or LCD display takes some small amount of power in the 0.1-0.2 watt range.
The 0.5 Amps calculated is consistent with the 0.4 Amps load I'm measuring.
If you have the original solar controller set up the load is a bit lower by about 24mA (0.024 Amps). So what is the major contributor to this parasitic load?
It's the Precision Circuits Inc. Battery Isolation Manager (BIM) that is specified to draw 4 watts. That's a constant 0.333 Amp load on your batteries that can't be turned off with any switch or circuit breaker.
This works out to a 10-12 AH depletion of your batteries every day. You can then understand why your batteries will go flat in a few days to a week if they aren't charged by solar or an AC plug.