isolator

I am in the process of setting up a system in my '01 4.7L V8 Durango. The system is going to include: Kenwood KVT-514 HU w KNA-G510 GPS unit Rockford T1000-1bd for the subs Rockford T-400-4 for the mids & highs 3 12" Alpine Type R subs in a ported box 4 6.5" P1S652 speakers for the doors I am considering installing a 2nd battery and isolating it so that I can run the system when the truck is off w out worrying about killing the starting battery and also so that I don't have to worry about draining the batteries killing each other. I have the stock alternator in the vehicle which I think runs at 136 AMPs. My questions are: 1) Is a 140 AMP isolator good enough? Should I go with something larger like a 200 AMP one? 2) What's the difference between say a Stinger 200 Amp Battery Relay Isolator SR200 SGP32 ( eBay) and a NOCO IGD-200HP ( eBay)? 3) Which type of isolator would be best for what I am looking to do? Thanks in advance!

The borg warner r3098 battery isolation relay I believe is same one or VERY close to it that stinger uses for there relay. it's about 45 bucks at lordco in bc canada (with decent discount) it will be cheaper in the states for sure.   I'm going to start with a ford truck glow plug relay that I have laying around see if that's up to the continuous use. I personally wouldn't use the diode relay's... I also wouldn't run the system for more that say 10 min without having it running or a charger on the battery just to avoid running a battery to low then having the alternator fry trying to charge it. I'm stuck with my stock alt till I find out what delco remy alternator to start with for the civic :)

i am an idiot wrote: If you use the relay type isolator, make sure you put a switch between the ignition source and the coil of the relay.  If you drain the back battery, you want to start the truck before you introduce the dead battery into the charging system.  If you do not delay this until the truck is started, you will simply discharge the front battery into the rear battery and then the truck may not start. The solid state isolators have diodes inside.  You will lose a little voltage going through the diode.  Usually about 1/2 volt.  If you do go the solid state route and can afford the 200 amp unit.  Get it over the 140 amp unit.

In the grand scheme of things how much is my system going to miss the 1/2 volt you think?

Since your amps probably have a regulated power supply, you will probably not even be able to hear a difference.Some people are sticklers for supplying their amp with as much power as possible,    Just wanted to make sure you had all the info you needed to make your decision.