My solar panels primarily charge the LB's then if there is excess it goes to the vehicle battery. It is controlled by a BattetyMaster circuit and in 10 years, kept off EHU, the VB
has only caused a problem once when it died.
The drain on the VB
primarily comes on starting, the other drains include the radio, immobiliser and alarm circuits and the clock on the dashboard. The radio has the twenty minute protection working and I have found having a 5w briefcase panel tilted and facing south on the dashboard keeps enough power going in to keep the VB
fully charged. The same happened when we lived in Devon, but of course, here in Aquitaine it is more likely to have a good input.