Finally switched to Intelligent Octopus. So last week I let Octopus charge the car. It worked - well sort of - the Zappi was in eco+ with a boost set to the off peak hours and it ignored the Octopus charge slots and used the Zappi boost timer.
Anyway - I set the battery timed charge to the off peak hours to avoid draining the batteries. Next day I set the timed charge to off.
The last couple of nights the master inverter battery charged up the other inverter battery starting at the charge times I had previously set. I've double checked the settings on both inverters - both off.
I have had cross charging before - but not in such a predictable way.
I know dual AC inverters are 'not supported' by GE. Most of the reported data is garbage - I accept that. But this cross charging at an exact time is new.
Where is the EMS?