Burstner Aviano IT944 Control Panel

[AndyHereford]

I have a 2007 Burstner Aviano motorhome with a an Elektroblok EBL99 transformer / rectifier and an IT944 Control Panel. Over the last couple of weeks the Control Panel has started showing a permanent current "drain" of approximately 9amps (whether or not any appliances are switched on) and it still shows a drain when the van is connected to the mains. Swiching appliances on and off and switching the Elktroblok on and off seems to have no effect on this reading! Any ideas out there as to what might be causing this issue. The batteries seem to be taking a charge OK when connected to the mains and holding a charge reasonably well when parked up and not on hook up. All other features on the Control Panel are fine and everything else in the van is working correctly. The van has two batteries fitted. One possibly the original as no paperwork indicating when it was replaced and one newer one that was, presumably, put in when a privies owner had an inverter fitted (the inverter is switched off) (?) (?)