Anyone ever run a smaller secondary battery into their trunk for audio purposes?

I have been thinking of adding a Shuriken SK-BT20 to the trunk to run my amps from and maybe even replacing the front battery with one smaller as well.

Thoughts?

Here is some info on the battery above:

http://www.bicostereo.com/index.php?act=viewProd&productId=5622

-High Performance Battery for use with audio system
-Handles up to 600 watts RMS
-Built with AGM (Absorbed Glass Matt) technology allows the battery to be mounted in any position without spilled
-Resistant to heavy vibrations and heat
-Super low ESR
-Amp Hours: 20ah
-Cranking Amps: 850a
-Weight: 15 lbs.
-Dimensions: 3"D x 7-1/2"W x 6-1/2"H

Make sure it's a sealed battery that doesn't require venting. I couldn't tell from the link if that one was or not. The vapors released from a battery can concentrate to deadly levels very quickly inside the cabin of a car. Otherwise it will work, but you're still dealing with our wussy alternators. Basically it's a bandaid fix.

Would it be good to possibly go with 2 small batteries one up front and one in the back? The one I suggested is a sealed battery and can be mounted in just about any direction or location.

The problem you're still dealing with is the fact that the alternator really isn't up to the job of keeping up with the draw that a big stereo creates. An extra battery takes some of the stress directly off of the alternator for a while, but take a good long drive with the stereo bumping and eventually the alternator won't be able to keep up and you'll either burn it out or drain the system.

Bummer. I guess I'll just to find one of those high output alternators then as a long term solution in addition to using one of those small batteries.

There you go!

I found out the hard way years ago that you can't ecsape the lack of a high output alternator with a big stereo. Things like backup batteries and capacitors help to soften the blow to the charging system, but they're just bandaids on a bleeding artery.

There's a little math involved in figuring exactly out how much juice you actually need, but I figured out years ago that a 1600 watt stereo (what I had in my car) needs ~120 amps of current at 14 volts to play at full tilt. Normal listening was at half volume so the draw would have been around 60-80 amps. Running the car takes about 50-60 amps without the heater/AC, lamps and stereo. Our alternators put out 85 amps IIRC.

Quickie math!
85 amps output
- 50 amps running power
- 80 amps stereo draw
-45 amps excess draw

Your system may not be that big, but you get the idea.

seems the stock alt is 90amps. I have about 1200watts between my 2 amps.

Fun stuff.

Meh, I was off by 5 amps :D

Originally posted by RoninEclipse2G
Meh, I was off by 5 amps :D

That's right.. now I have to give you negative points!

Any suggestions to a reputable place that sells a good high output alternator for our cars?

I knew there was once a place called 4altstart which seems to have moved to http://www.alterstart.biz/ now and I was probably going to go with them back then. I wonder if there are other places that anyone else may suggest.

youll be fine adding a 2nd batt in the trunk, as long as its a sealed batt. also if your just running a 1200w amp, there is no need for a high output alt as long as you have the 2nd batt. i had 2 3000w amps in mine with 3 xs power d3100 batts on the stock alt and had no issues. you can also add a volt meter, i use the stinger one that you can find on ebay for bout 25, so that you can watch your voltage to make sure its not dropping to low.