Interesting question.
If you only have your batteries with no means of charging it, then the fridge will run about 2 days when not set too cold.
Once you also use charging for phones etc, lights, and the water pump you reduce this to about two days.
So how do you increase your off the grid time?
- Use a generator to charge the batteries.
- If driving every day, the batteries should charge up enough to last however long you will be on the road for.
- Use solar, the charging of the batteries will depend on how much sun you have and the watts it generates. In theory with really good panels you can stay off the grid for quite a while, if you are careful with how you use it.
- You can also change your batteries from lead acid to lithium, however at the moment lithium batteries costs five times more than a lead acid battery. But, it has the potential of lasting up to ten times longer.