for a 2 devices that are not used at the same time a 230V power supply from 12V is required, so and now to the data: Device no.1= 200 watts (use for approx.40 seconds * 200 times a day ) Device no.2= 250 watts (use for approx.10 seconds * 200 times a day) These devices are not switched on together but according to each other as required. Who (professional) has for me a solution, these 2 devices depending on needs about 6-10 hours to operate over batteries ? What for battery(s), brewc he me ? How many batteries do I need ? What power must have at least the voltage converter ? What to pay attention to when buying voltage converter ?