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.

While fishing or at anchor I switch to Batt #2 which powers the VHF,
sounder/GPS/Chart, and bilge pump.

Now and then I start and run on Batt #2 or Batt #1 just to be sure either have
the capacity to start the O/B.

The batteries will be five years old in April so I'll probably replace them. I
hate having dead batteries out in the middle of nowhere with no boat in sight.
Batteries are cheap tows are not.

Butch

Mark wrote: snip 1 - why is this system utilized (why not just 1 battery?)
and what is
the proper operation of this system?
2 - should I always have it switched to "both" so both batteries get
charged when running? what is the preferred switch scenario?
3- which battery is better to run the electronics to? (I imagine the
deep cycle.)snip

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.