On our CC the outlet in the oil reservoir fill door was no longer available. The only indication of an external charger for the chassis batteries was a 120vac plug hanging down from the ceiling of the engine bay. When parked for long periods I run an ext. cord from a shore/gen outlet in the tool bay. Be sure you plug into an outlet that is only hot when plugged in and not powered by an inverter. On ours, we only need to plug the chassis battery charger in for a day or so every three weeks so it is not a big deal. I never have been able to find a plug in for an engine heater.