Hello Linda. As a rule of thumb everything from the drivers seat back uses power from either the leisure battery or hook up. The radio in general runs off the engine battery unless a previous owner has altered things and routed a supply from the leisure battery. Regarding the lights I assume you mean the interior camper lights? The courtesy lights that activate when you open the doors are powered by the engine. The rest use the leisure battery/hookup. When on hook up your leisure battery will be charged too. I hope this helps.
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