On EHU both batteries are charged. On Solar, just the leisure batteriy. Are you saying that thios would not work to charge both on Solar??
Yes a BatteryMaster would work fine to charge the starter battery from the leisure battery on Solar. I think he was saying that if you have access to EHU all the time, and it charges the starter battery too, then a BatteryMaster is not necessary. However some people have limited access to EHU, on site and during storage, so a BatteryMaster is useful to keep the starter battery topped up. And some people just want to stay off-grid, parked by the beach, and spend the holiday surfing. So a BatteryMaster has its uses.
Yes a BatteryMaster would work fine to charge the starter battery from the leisure battery on Solar. I think he was saying that if you have access to EHU all the time, and it charges the starter battery too, then a BatteryMaster is not necessary. However some people have limited access to EHU, on site and during storage, so a BatteryMaster is useful to keep the starter battery topped up. And some people just want to stay off-grid, parked by the beach, and spend the holiday surfing. So a BatteryMaster has its uses.