Hi guys

Just after a bit of advice

Im soon to install 2 amps, one Alpine PDX F6 4ch, rated at 150W RMS per channel, also a Alpive PDX M12, rated at 1200W RMS

So thats a total maximum output of 1800w RMS

I am told by a local car audio guru that due to the current draw, I would be best installing a second battery in the boot to cope with the load as he says I will get too much of a voltage drop just running 0ga to the boot, which would need to be around 5 metres in lenght

Whats peoples thought on this?, I dont really want a second battery, but if it is best to have it, I will

I was planning on using a Optima D34 Yellowtop, which this guy claims will barely cope with this system.....

Im just not sure whether to take his word for it, hes not trying to sell me anything, so I cant see why he would intentionally lead me up the garden path, doesnt seemvto be that type of person either...

So, do I go a second battery or not?

Cheers

If you are heading for serious sound competitions with this lot, a second battery would be good. Connected to the car's charging system to keep it juiced up, but with an isolation switch to make sure the front battery doesn't go flat when parked and in use.
How much current would this setup draw at max decibels? 1800W RMS = XX amps @ 12V?

Im told its around 170 amps......

Not heading for sounds comps, but theres no point in doing what im doing without ensuring it will get sufficient juice, so putting it out there for discussion

http://cartech.about.com/od/Car-Audio/f/Do-I-Need-An-Extra-Battery-For-My-High-End-Car-Audio-System.htm

this article may answer some of your questions,

If I was you I would get an Optima Yellow top, upgrade the big 3 and see how it goes first

Hmm, that was actually an interesting article, gave me a perspective I hadnt thought about

So my next thought would be....capacitor?

In all my previous audio installs a capacitor has never been needed, and to my knowledge they are pretty much a waste of time and money

But it has always been in the back of my head surely they were designed for a reason?, perhaps more applicable to older cars with low capacity alternators?

So my question would be, at what power draw point should one perhaps look into whether a capacitor will be of any benifit?

http://www.nanopulser.com.sg/capacitor.htm

see what this guy thinks of capacitors in a car sound installation!!

Yeah well, that just reiterates to me that nothing has changed, capacitors are not worth the cash..

Looks like ill just go ahead and install the yellowtop in the front, see how it goes, if I have issues ill work it out then, but fromcthe info im reading, it should be sufficient

Thanks for the links guys!

Bud, forget the cap (which you have), and 0 gauge will be enough.

Will you be doing alot of engine off listening? Also keep in mind music is not a light switch, its not 1800wrms or nothing. A D34 will be fine, upgrade the big 3 while you are at it. Honestly if you wanted to make a custom battery tray id go for a D31 but thats overkill anyway. If you can get one easily look into a fullriver HC65, these a better than optima batteries, can handle more and better build quality.

Look if you get stuck and really want to look into this technically use the calculator on this site, page 16 under "wire"

http://www.bcae1.com/

Thats a very good reference.

After 4 years my D34 is struggling but only with engine off listening, with all my accessories on im lucky to get 30 mins of listening but my system isnt a small one, but when it comes to engine on listening and cranking over the engine still does it no dramas.

May I ask what do you mean by upgrade the big 3?

The BIG 3 is to upgrade or add bigger wire from alternator to battery (+) and battery to engine block (-) and engine block to firewall (-).....

check this link for more info
http://www.caraudio.com/forums/wiring-electrical-installation-help/152355-official-caraudio-com-big-3-thread.html

on the other hand, in the web site that 'peaandham' refereed you to warns you to be careful not to by-pass any safety cut outs the car electrical system has.. (scroll down half way page you see the big3 title)
www.bcae1.com/chargin2.htm

The longer the wire, the higher the resistance, sometimes the positive run you make for the alternator wouldnt even really be getting used as current will take the path of less resistance.

I did this, made no difference.

I would recommend upgrade the battery to chassis and battery to engine block ground though.

Many moons ago i had 2x big 15s. I added a Cap and it was a massive improvement with 0 gauge running to battery too. I was then told to add a battery and reluctantly i did. Holy hell, it was a massive difference in bass. I would recommend it all day. Current has to travel under 1m where before it had to travel 5-6m. If you dont have a cap dont put one in, just go for the battery, if you dont want a battery in the boot just go with a cap. Why do you think all the Audio cars run battery's in the boot for..:)

Ahh great....now im indecisive again....lol

Will have to give this some thought......I assume if I wire in another battery I wire the positive straight to the alternator correct?

Been reading up, and one arguement put forward is a second battery can put alot of strain on the charging system, what are peoples thoughts on this?, it is claimed the average alternator is not designed to be put under such load for long periods of time....

I dunno......lol, asked a question, now im more indecisive than I was before I asked it.... :)

A Second battery will always put extra stain on your charging system as it now has double the work load. Best option is go with it till the Alternator packs it in. Replace it with a standard one which is cheap as chips or get a higher amp one to replace and compensate for the extra load. When it comes to wiring, just run a 0 gauge wire off existing positive terminal on the battery. Run a short as possible earth from the boot battery to the body. I have always found the child restraint mount is good value and you just Stick a bolt in from the bottom to secure a good earth, Assuming you dont have a child seat in the car.:)