I have a Northern Japan Bongo so have 2 starter batteries under the bonnet & my leisure battery is in the Mazda Kitchen cube to the rear near side, with a split charge system in place, but my old leisure battery has had it, holding no charge when engine off.
Do I need to disconnect the starter batteries before disconnecting the leisure battery? & if so in what order?
Again forgive my innocence, I am learning!

TIA
