Those of us who have big stereos and spend most of the time rafted off use
the #2 battery while at anchor.
Those big amps will pull a battery down in no time flat.
We anchor/raft off and throw the switch to #2.
It's also nice to have a second as a backup, but have never needed it for
starting.


"JDavis1277" wrote in message
...
Mark,

Except for trolling motors the primary purpose is redundancy. It's nice
to
have a backup.

Both of my batteries are starting type. When starting and running I use
both.
Swithching while running is not recommended. Damages the alternator.