Extra battery? Better alternator? Caps? Or all three?

[Keske944]

First off thanks for all the help you guys have been giving me on this site. It really helps. Ok so I am still working on my system and just bought my two Polk/MOMO MM10's. So here is what I have and it is almost ready to go in the car. I have three Polk/MOMO MM6 componet systems powered by an Audiobahn A6601Q (75w x 6 @ 4 ohms), two Polk/MOMO MM10 subwoffers wired in parelle to an Audiobahn A18001DQ (1200 w x1 @ 2 ohms so the subs are getting 600 w each @ 4 ohms), and a Kenwood eXcelon KDC-X659 face. I am planning on buying an Optima Yellow Top that put out 870 cold cranking amps. I am driving a 1987 Porsche 944 non-turbo. I am not sure how many amps the alternator puts out. Now to power this beast of a system would you guys suggest just the Yellow Top, a better alternator, caps, a second battery, or what? I am basically building my system based on your suggestions so I don't get burned by salespeople just trying to get a little more commision. On a side note my amps are fused and I am running a 200 amp circut breaker (A6601Q 60 amps in thirty amp fuses A18001DQ 150 amps in thirty amp fuses 210 amps total). So will I be fine with my current alternator, the Yellow Top, and three caps? Or do I need to upgrade the alternator to power everything?

Thanks in advance,

Adam Keske

[PoweredByDodge]

well... first, i think you should get rid of the circuit breaker and replace it with an equivelant fuse (200 amp ANL style). The reason being this -- sometimes, if for some reason, the whole world goes to hell and you get some sick electrical short, you can actually "fuse" a circuit breaker, which means it gets electrically STUCK in either the open (off) or closed (on) position. If it gets stuck in the off position, then its no big deal, its as if you had blown a fuse, like you'd want it to be... but if its stuck in the on, then that could defeat the entire purpose of having the circuit breaker at all. Sure, fuses cost 5-7 bcuks each, but they are a bit "safer" for the equipment.

As far as what to do with everything else... 1,650 watts is a good healthy system there... that's about 120 amps current draw when you're slamming.

If you're alternator is at least 80 amps or better, you should be "ok"... ideally you'd want something in the 120 - 130 range, but porsche alts cost $$$ and in all reality you can get away with 80 or better. (as far as what yours actually is, I've no clue, but luxury cars usually have at least 80 - 100 if not more).

I would not get an optima battery... a yellow top is designed for use in a trunk, in a passenger cabin, somewhere other than under the hood (this is why its a gel cell instead of a lead acid cell battery - its safer near people), and this is why you pay a lot more money for it (200 dollars).

If yoou're mounting the battery under the hood like normal, then a good Die Hard / Energizer / Exide / Interstate will give you the same performance, if not better.

Napa Auto Parts as well as some other vendors still sell Exide batteries... Exide used to and still does make an 1,100 CCA battery. It is about 75-85 dollars I believe. This battery, in conjunction with 2 capacitors ought to do well for you. (rule on caps -- once you've made sure your electrical system can support your audio system, add 1 one farad capacitor for every 750 - 1000 watts rms, so as to ensure a smooth voltage with minimal to no drops). You can get lightning audio strike series caps off ebay for 65 bucks shipped each. When shopping for caps, just look for something with a 20 volt surge rating or better (not 16) and a major name brand -- as many lesser brands such as pyramid use a poor quality foil and a poor quality dielectric material.

If you can't find the Exide -- a 900 CCA Die Hard or Energizer for 75 bucks will do the same job as that 200 dollar optima 875 CCA... again, the optima is only "better" if you are going to run the battery down to zero volts (completely dead) and recharge it numerous (more than 5 or so) times or you are going to put it in a passenger compartment near people.

I do not believe you'll need a 2nd battery... I was "almost" ok with one 900 CCA battery and 117 amp alt and 3 caps running 3000 + watts. I really think a single good quality high CCA batt, 2 one farad caps will do the job.

Also, be sure to use something heavier than 4 gauge from the battery to the distribution setup... your main power wire from the battery to the amps should be 2 gauge. 4 gauge will only support about 75-80 amps safely over a 15 foot or so long run. you could use 0 gauge, but you only need 2 gauge for the 120 amp setup you're talking about (2 will support up to around 150 amps over a 15 foot run) and considering the price difference between 2 and 0 is about 2 bucks a foot, its worth it to go with 2.

[Keske944]

Thanks a lot. I am going to use 0 gauge wiring as I will be running both amps off of it. As for my alternator I have found out that it supplies 113 amps so I think I should be ok. I am thinking of using at least two maybe three caps (two for my 1200 w amp @ 4 ohms and one for my 450 w amp @ 4 ohms). My amps are Audiobahn and I kinda want it to all match so I will probabbly go with Audiobahn amps even though they are more expensive.

[PoweredByDodge]

audiobhan has a 3 fard (i think or it might be 5) cap that is like a "mini amp" -- its like a square block that sorta resembles the amps and is made to match -- last i saw it was about 300 bucks but im sure ebay has it for less.

[Keske944]

I've seen and but my trunk isn't quite that big. It would fit but it would be kinda tight. I think that I'll just go with the three cylinders as much as I would like that amp style three farad cap.