You can do ether, If you know you have a issue with the starting battery then I would personally leave the parallel switch on. If the battery was just low and need some help to start then make sure both switches are on and turn the parallel off that way it will be slightly less load on the charging system and once the main start battery is charged then the ARC will start to charge the house secondary battery up. Do not turn off the Red switches while the engines are running.
After the start using the parallel option do you flip the parallel back to off during ride home? Or, leave it in on position all the way back to dock?
You can do ether, If you know you have a issue with the starting battery then I would personally leave the parallel switch on. If the battery was just low and need some help to start then make sure both switches are on and turn the parallel off that way it will be slightly less load on the charging system and once the main start battery is charged then the ARC will start to charge the house secondary battery up. Do not turn off the Red switches while the engines are running.