If I have a dual battery switch plus the dual bank on board charger, do I really need and acr unit.

Boat sits on the lift with electrical access right there at the house.

Never had a problem this year, but liked the vsr in the old boat but I did not have the on board charger.

I assume when I run the boat with switch on 2 while under way, the alternator will top both batteres off.

Any thoughts..