Fridge , driving and camp lights , hot water , inverter - the list goes on. Mostly the fridge for when you're in camp.Oh and if for whatever reason the starter battery dies somewhere remote, you have a backup.This type of product is useful because you can take it outside the vehicle and to the next vehicle if you sell up. All the work has been done and it easily connects to a solar panel. I might go this route with a slimline battery. AGM , maybe later lithium. https://www.australiandirect.com.au/buy/kickass-portable-battery-box-power-station-with-in/KAJBAGMKIT1Blaidd.drag.mike said:Just wondering here. What specific accessories would benefit from the second battery?