No 12v power with battery removed but 230v connected

[Alanbrooke]

Just removed my caravan battery for the winter and connected 230v supply to the van. There's no 12v supply at the control panel for lighting in the van. I don't remember this happening last year or previously. 230v sockets and microwave all function. What am I missing?
Alan

 

[Hutch]

This happened to me at one time, the PSU, power supply unit, had two 12 volt supplys, 1, to the caravan and one to the Battery for charging. The 12 volt power supply to the caravan had burnt out and the battery was supplying all 12 volt power, but was being charged.