Our present 5er came with garbage batteries. It was a '17' model clearance,'16' build, 14 months give or take on the lot.
First time I ckecked the water it looked like lead soup which I had never seen in a battery.
They seemed to hold a charge and we spend the majority of our time on shore power.
They were good enough to take us to Alaska and back in '18' but I replaced them at Costco with 2 6v GC in '19'.
Ckeck them regularly and have added water once in 2 years.
Previous 5er a used 6 yr old came with 2 12v of undetermined age. 5er was well taken care of so the batteries may have been replaced they did require bi monthly watering.
The converter died 10 months after purchase. It was replaced with a PD
Converter don't recall the # but it was an upgrade over what it had.
It did cut down on water usage for the batteries.
Replaced those batteries with Costco 12v batteries water useage virtually a non issue. We traded 4 years later.