Quote Originally Posted by wgriswold View Post
I don't know about our cars but on my sailboat with two batteries there is a special "make before break" switch to change from one battery to the other. The common knowledge is that if the battery is removed from the charging system the alternator will be damaged. I have not tested this. I would expect the same to be true for car systems.
The alternator and/or the electronic systems can/will suffer, in cars as well as in boats