Battery Connection -- What's in box "1" or box "2"

[Olive]

Please redirect to a previous thread if I'm asking a redundant question -- but here's the question I dealing with tonight...

Battery 1 == old, mca = 500 deep cycle -- passed the "murray's" test but was leaking fluid... I've decided to replace this battery (btw, this battery currently has everything connected - engine, bielge, stereo)

Battery 2 == new (just installed a two battery system) -- mca = 500, deep cycle format -- designed to run the stereo while I rest my weary bones

Question -- if I install a "starter battery" as #1 -- mca = 1000 and uses this as my "primary" -- start and stereo for extended times will I be ok with having my battery 2 as the "saviour" battery and restart on "all" -- until battery one is recharged?

I did read on this forum that batteries in parrallel will reduce to the weakest state -- so would I be at risk for a lower MCA?

Sorry for the long post -- but:

One fix would be to have a stereo lead that conneceted to Battery 1 and to battery 2 -- use the starter battery until "drift time" and then switch over to the deep cycle battery 2 -- restart with battery 1.

or

Would I be better with a new deep cycle mca = 500 and run the always in the "all" position -- any run down at rest would be added to the mca = 500 of the resting battery??

Lots of questions -- thanks for trying to make sense of my rambling...

Regards, Olive

[l1spoogy]

Here is my setup which has worked for me.

Perko switch 1 2 both and off.

Battery 1 Marine starting Battery.

Battery 2 Marine Deep Cycle.

I leave the perko on position 2 99% of the time that way I always have position 1 to start.

About once a month I put a charger on battery 1 to maintain charge. The altenator keeps battery 2 charged.

There are two reasons I do it this way. First is I never have to remember to switch batteries when I stop for an extended period of time. Second if I do drain battery 2 I can just switch to battery 1 and be confident I won't be stranded.

You have to be sitting for a long time with the stereo playing rather loudly to drain any decent deep cycle battery. A few weeks ago we had the boat off and the stereo playing for nearly 8 hours and the boat started right up on the same battery. I have never been stranded doing it this way.

I never use the "both" or "all" position.

David