Hey guys,
Because of my audio system, I am needing to add a secondary battery, I already know to wire them in parallel, but, will i need like an isolator switch like this http://www.supercheapauto.com.au/online-store/products/SCA-Battery-Terminal-Isolator-Switch.aspx?pid=214448#Description obviously not the super shit auto one, but a better version?? or will i have to go for a relay or solenoid or something??

What makes you think you need a bigger battery???

Second battery is a good fix for headlights dimming, etc.. a better fix is a bigger alternator but they dont' seem so easy to get in Australia - in the US there is a company that makes them for most models but not here.

Rather than one of these battery terminals what you want is a proper battery isolator system that cuts the rear battery from the front while the car is off. So it charges when on and doesn't touch when off, more commonly seen as 4WD kits etc.

Have you thought about getting the big 1 farad capacitors???

What makes you think you need a bigger battery???

Im not needing a bigger battery, im wanting to have a second battery, thats a deep cycle one, so i can run all the amplifiers and monitors in my car, coz atm my main battery will drain in about 30 mins when the car is off, and that means i have to always have a jumper pack with me, just incase

Get a decent deep cycle for the rear if you have to. I swear by optima myself as i have never been able to flatten it lol Dont need an isolater but can use it if you like. Probably run some decent power cable such as 0ga to the rear battery aswell. Depends on your requirements for current. rms etc

DO NOT bother about a capacitor. Do more harm then good and are useless proven time and time again. Upgrade your power cables in the engine bay to 4ga or 0ga. They call it the big 3. Power from alternator, ground to body from engine, and ground from alternator. Best thing you can do as far as dimming headlights etc go. Will also increase power capabilities

thanks mr spl, have already done the ground to body from engine and ground from alternator, is it safe to just run the 0ga to the deep cycle battery from the positive terminal of the front battery??

Question - before adding a second battery - Do you have a high quality primary battery? If not, invest in that first.

I assumed the OP had a decent quality primary battery. To answer your question its perfectly safe to do it as long as its a deep cycle / cca battery. Not just pure deep cycle as they must be trickle fed

yeah i sure do have a decent primary one, its an optima red top battery, and am wanting to put in a yellow top in the boot for my amps and monitors

Fair enough if you think you need it :) Like i said im more then happy with optima!