I’m trying to understand how the electrical system is working.
After a few minutes on external power, I get a Battery Discharge warning.
Both battery switches are off. But the electrical chart is showing that both batteries are outputting 26 volts.
The connection from the batteries to the mains are severed, so no power should be going anywhere from the batteries. This is confirmed when I turn the external power off, and see everything turn off.
External power is on and the chart shows power routing all the way up to the left and right main bus.
So what’s drawing power from the batteries?
That is a really good question!
I’m thinking this is an error.
I wonder what the “Service” bus does (maybe ground service functions?). If you remain in this state for a long time, do you see your right battery voltage drop? The lines from the right battery to Service remain white, so I’d expect there is a relay in-line that cuts power from flowing to Service via the right battery when external power is plugged in, but it’s odd that isn’t identifiable visually.
Perhaps @Bishop398 will enlighten us.
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The only thing I can think of would be items on the Hot Battery bus causing a discharge. There’s really no reason to run it in this configuration though, if the GPU is connected and selected, the batteries would be selected on. This configuration would be a maintenance function, so if the GPU fails, it doesn’t drain the batteries.
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The answer in this case, is nothing. The current shown is 0A. A voltage being shown is just the current battery charge level, and does not indicate current being drawn from the batteries.
This is because this is not a normal configuration for the aircraft. If power is being supplied to the buses but the batteries are not being charged after some time, the CAS will throw this warning. It is intended that if the aircraft is powered, whether via external power, engine driven generators, or the PTCU, the batteries are connected to the buses and receiving charge.
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Ok, I think I understand now. So the normal procedure is to always have the batteries on regardless of the power source.
