We have an inverter in our van and generally use it however for extended stays and lousy weather at times we have also used power banks as well. They can be charged whilst you drive to and from places in the car for the day or when you go to the next place. Ordinary small one will work on phone and ipad I am using Cygnett 15,000mah. Picked it up from a telstra shop in our travels.
macbook pro requires a much stronger power bank. I am using Cygnett USB-C 27,000mah. Picked this up from Harvey Norman shop after much mucking around. These can be precharged and only have to be topped up when needed.