Name:   sagetek1 - Subject:   Dual battery use question Date:   2/25/2020 1:27:00 PM

Pretty much what I do. The switch is "supposed" to be a make-before-break switch but like you, I NEVER switch batteries when the motor is running. Do not know if modern alternators could take the open circuit situation, but do not want to chance it. I too have for years heard the alternator damage question, and at one time there was even a device to put on large alternators like on Mercruiser boats (had one years ago in a large 24 foot cruiser at the gulf) to prevent this damage. Ran dual batteries there, but one was for starting and one for house. Could be paralleled if needed. Had sophisticated charging system to keep both charged even though mismatched. The ones I have now are the same.