My elderly camper fritzed both the engine and house battery at the same time recently. Seemed a bit coincidental. I though maybe overcharging? There's no passive drain going on and the batteries are isolated from each other when not in use. I put a new engine battery in, charged with a smart charger, left it to rest 24hrs, and measured it at 12.83 volts. Started the engine, ran it for an extended period but the charge voltage into this fully charged battery never dropped below 14.4 volts. Surely over a period that would produce gassing? I thought from my previous experience with boat systems that a good float voltage should be no more than 13.8v? Or am I just overthinking this? I have a long track record of doing just that! Any bright sparks (groan) who could put me straight?