I have a AF-5500 with the TCW backup battery. Recently the TCW battery failed. TCW stated the battery had been discharged to the point of damaging a cell. I had to replace the battery. Other than annual tests I have only used the TCW battery once after an alternator failure, that alternator failure was over a year ago. During my discussion with TCW about the battery I believed they mentioned an issue with some Dynon AP panels drawing a low amount of power from the backup battery after shutting the system down.

If the aircraft sits for a week or so I am starting to see a large demand of amps shortly after engine start and the voltmeter monitoring the TCW shows high voltage as if it is need to recharge. Is there a known issue with devices on the Dynon network creating a "trickle" drain? Possibly running the device lighting?

I have the TCW wired to the 5500 as described in the installation manual.