Have a look back in the archives on this forum - lots of posts about this topic.
Do a few calculations first so that you can get an appropriate sized
battery(ies) for your needs. Add up all the watts @ 12V that each appliance uses and then estimate the number of hours you will use them for each day. You can then use the formula (Watts / Volts) = Amps x Hours = Amps Hours - which is the usual method for rating a
battery. Or goto
Electric power calculations voltage current and resistance - electricity calculation - electrical power general formula ohms law physics formula wheel power formulas amps watts volts ohms cosine equation audio engineering pie chart - sengpielaudio Se to do it for you.
Next step is to understand that not all batteries are made equal - cranking batteries are designed to start a vehicle, draw a large amount of Amps for a very short period, and then be recharged by the vehicle alternator. Cranking batteries are not good at being discharged and then recharged and will fail within a few months when used as a power source for appliances/lights.
Leisure batteries are a compromise between a cranking
battery and a full on storage
battery. They are capable of being discharged lower than a cranking
battery but will not recover if they are fully discharged continually. Leisure batteries come in all sorts of different internal configurations - lead acid, gel, glass mat, etc.
Lead acid require the
battery to placed upright with the vent at the top.
Gel and glass mat can often (not always) be fitted in any position you like, which often means you can fit a much larger
battery into the space available.
Forget about storage batteries as you need a truck to carry them.
Inverters - unless you have an over riding need for 240V appliances then why bother. Again do the sums and have a look at the watts drawn by 240V appliances and what the startup Amps is for the appliances you want to run - some friends wasted a lot of money on an
inverter to find out that it could not provide sufficient Amps to start a 240V water pump - pump drew about 3Amps when running but needed about 15Amps to start it.