Ok, so I've installed a huge ass stereo... and the wiring for dual batteries. (and new braces)

the idea is to have 2 fully charged batteries ready

run on that

when we stop, switch to Batt 2 and play the radio all day with no fear of a dead battery

then, using Batt 1, start the engine. then switch back to 'both' while it's running to charge both.

so, my question is... Can I use 1 starter and 1 deep cycle battery? will the boat charge both just fine?

Or do I need two identical batteries? They will both be new this spring, just need to know if I can mix the types...

You can mix both. Instead of a switch, you can wire in a solenoid that brings your stereo battery into the charging circuit only when the engine is running. When you shut it off the battery is seperated. I have done it with a battery switch, yes and forgot to switch it=two dead batterys.

that's an interesting proposition. I got the old school battery switch for free.

how would I wire your setup?

the leads for the amps are on Batt2, but to turn the radio on/off needs power at the 'boat' connection.

Go to Blue Sea site, and take a look at schematics for their automatic charging relay (ACR). I added a house battery (deep cycle) and ACR to my boat this past summer, and it has worked great.

NOTE: I've got a twin engine with a starting battery on each engine - one of those batteries was dual duty house and start battery (stupid design).

Very cool toys. Sadly my 1990 boat was single engine, single battery, so it was never really setup for 'house' power... no switch panel no nothing. everything comes from one battery connection.

That doesn't matter. Like I said, take a look a the schematics.

You can add a "house" battery to your rig with the Blue Sea Add a Battery kit. It will allow your starting battery to be used for its purpose, then have a house battery for your stereo. When running down your body of water, the alternator will charge your starting battery - but once it reaches adequate charge, the ACR switch over to charge your house battery. Once you are at your float/raft/anchor spot, the "house" battery would be used and isolated from your starting battery (cheap insurance) - therefore, no discharge of your starting battery while playing your music. Of course, a switch will work for this - however, the ACR makes it automatic.

I believe the kit is about $100. Mine was a little more elaborate with twins, but concept is same. I never touch my battery switches unless I'm wanting to turn all systems off (starting and house).

very cool. I will look into it

thanks!