Help Needed for Dual Battery Set up

[Hurlz07Tahoe]

I've never set up a second battery before, so I was wondering if you all could give me a little help. I know I want the same type of battery, want to put it in parallel, and I want to make sure my alternator can handle it. That's about it. I'm an engineer so I think I can figure it out, but I not all that great with electronics so any help would be appreciated :)

First - do I really need the second battery? I am going to be installing two air compressors (1 for to control my Rancho adjustable shocks, and the 2nd to inflate my rear airlift bags and a 2 gal reserve tank). Each compressor is 12V, and the 1st is 10Amps, and I think the second is probably 15Amps (I havent gotten it yet). I do tow a lot with it, but I'm not sure how much the trailers pull from the batteries. I may put some off road lights on in the future and maybe a small upgrade to my stereo (amp, sub, etc).

Second - What battery should I go with? Is it necessary to get two batteries from the same batch (i.e. made together and have the same quality)

Third - Got any help for actual installation?

Thanks!!

[stevek]

I always recommend Optima Yellow tops... they're great batteries.

I also recommend getting a battery isolator. It will disable one battery when the car is off so you're only running off of one battery instead of both of them. This will become handy so you still have a working battery if one of them dies.

[Modded]

To tell you the truth, I would rather just get a HD higher AMP alternator and you will be good to go.
But then again maybe I am biased in saying that becuase my second battery tray is taken up by a Wolo Truckhorn.

[BigRed76]

I also want to add a second battery and am looking for anyone who can take some pics of their under hood setup and clearly explain the steps necessary to complete the project.
Thanks!

[Mgyver1]

I'd go with only one compressor instead of two small ones. More versatile and will last longer. Like this one that even comes with 2 1gal tanks which can be taken apart and remote mounted:

http://cgi.ebay.com/1-HP-2-Gal-12-Volt-Puma-Compressor-New_W0QQitemZ380221862450QQcmdZViewItemQQptZLH_Def aultDomain_0?hash=item5886fd3232

You can link the compressor up to the tank and a manifold. From there have your air silenoids and regulators control the air bags and shocks. Also you can use it to air up tires, air horn, and in a pinch an impact wrench to change a tire (depending on tank size/pressure/how tight the lugs are/etc).

This is something a small 10-15a compressor can't do. The Puma is a 30-40a compressor. The OEM alternator is 160a so it'll handle it. My pickup with an 80a alternator running dual batt's runs it just fine.

As far as the batteries go, use an electric silenoid. My plan for the Tahoe is to have the batteries go in parallel when the truck is running (Triggered by alternator when it is charging) and seperated when the truck is not. Also you can wire up a switch to manually override and link the batteries so you can jump start yourself if your starting battery dies.

I think GM-trucks.com, the Avalanche forum, and maybe here have threads with the oem part numbers for dual batt setups.