Update I got my answer,
I got a call back from AGL the actual guy that sold me the system and he said.
AGL will always leave me with a minimum of 20% battery capacity in a worst case scenario should
the need arise to take that sort of power.
In short he said they can take up to 80% of available battery capacity if needed but will always leave you with 20% of total battery capacity as a minimum.
Cheers
John
