A usable capacity of "only" 18 kW-hour should run some residential fridges for 8 days, or run an A/C overnight with enough power left in morning to make coffee.
If cost ever gets down to $300 per kWh including battery management system, it will be a huge game changer in RV design. Most quality drop-in batteries I've seen are still in $1,000/kWh range at retail which makes them a little too pricey.