What you wanna do is quite simple... just have a big main power cable coming from your batt upfront with a heavy duty isolator switch inline, going into a distribution block in the back. Then have this splitting off with fuses/circuit breakers into your amps. Have your second batt feeding into this with a ciruit breaker inline. This way u can have it all switched on & charging, then get to the cruise and u can flick off the isolator switch and it will all run off your 2nd batt. Likewise if u dont wanna charge the second batt, just flick off the inline circuit breaker.
As for the alternator, depending on what engine and alternator you have originally you could do a simple upgrade. Mine is a 1.2 8v with a 55A as standard and i bolted on a 100A one as a straight swap, same sorta one found on a lot of 2ltr cavs and omegas. Easiest way to be sure is to go into a shop and decipher which one yours is, then get them to call up their alternator supplier and ask for one that is higher amperage but same mountings (if they're any good they should be able to sort this).
Nice essay huh :rolleyes:
U2U me if ya got any more questions m8 :thumbs:

After some info on dual battery setups,

Heres what I want it to do,

When the car is running I want both Battery A and B connected (so both will charge) What i want to be able to do is when im parked up (at cruises and shows) be able to turn Battery A off so that it doesnt discharge, and just run my stereo from Battery B, then is the battery runs flat it doesnt matter because i can run on Battery A to fire the car first time

Basically to aviod an embarrassing situation at a show last year where my battery ran flat (Dont let ur gf demo ur ICE for you!!!!)

Is this sort of setup expensive?? I assume i will need to get an uprated altenator?? what would i need possibly one from a diesel??