That new Hymer Charlie had, the truma heating had a problem, hadn't been installed properly. Can't remember what it was but dont think it was wire size. That was a 2017 model as well.
I used to have 3 x 90ah Bosch PowerFrame
battery's in my van, it had original split charge system through the EBL, twin mains chargers to allow for the extra ah's, 2 x 150W
solar panels with Votronic MPPT controller. I have a 110ltr Waeco compressor fridge and Eberspacher diesel heater which are my biggest power users. The
battery just about lasted me 12 months before capacity was too low to cope. For maybe half that time I was using the van 4 days out of every 7 and the rest full time so had a lot more use than most folks will do probably. That convinced me the Votronic B2B was what I needed, costs kept me to a 30amp model and I changed the batteries to 2 x 100ah
lifepo4.
My fridge uses 48 amps in 24 hours, dont watch much tv but charging laptops, phones, headphones, lights (led) and my Echo dot and wifi router take the total to around 65 amps per day. I dont switch my fridge off except briefly when it need defrosting. Before I was full time I was unable to fully charge the batteries before each trip and I could see a big difference outside the main summer (sunny) months when setting off without charging, even if a run from Derbyshire to Scotland. The batteries never really got fully charged unless I went on site for a few days which wasn't often. That combined with the fairly high (compared to most) and constant demand caused the early demise of the Bosch
battery's.
I dont think there is a right or wrong way (so long as things are fitted correctly) with van electrics, its completely down to what you want to do in the van. I know a lot of guys who go to the scrap yard and pay £10 to $20 for a scrap lorry
battery and run happily on that for ages, when it packs up they get another. They mainly run one or two less and charge a phone though. It can be expensive along the way finding the right solution though ha ha