Thread: High output alternator vs battery

Ive posted before about what to do on this
so lets see if i can get a few more opinions
im working on my car audio system, ill be doing a full audio rebuild
all polk audio speakers these will be polk DXi 6.5 inch components for the kick panels, db 5.25 inch components for the doors, and 4 inch and 6x9 inch coaxials for the rear deck. The front set and rear set will each be powered by thier own polk pa660 300 watt rms amp. Along with the speakers ill be running two RE audio SEx 10D4 subs on a mtx jh1200 amp wired down to 1 ohm. The polk speakers amps are on the way to my house already and ill be ordering subs and the sub amp in the next week so this is happening.

What I need to know is what I should do about the wiring. Ive got two options unless someone can think of a better one.

1. I can pick up an optima deep cycle battery for 100 bucks at my local audio shop and run the stinger 0/1 gauge kit ill be using from my current battery to the trunk and then run separate 4 gauge wires from there. However I'm not sure that will work, the polk amps are not cea compliant tho so I'm going to assume they will be over rated which would be a little less stress on my electrics. But the sub amp that im looking at has been tested to 1261 watts rms at 1 ohm so I know it will put out that much. This might work but I've heard a lot of horror stories with second batteries and I know my alt probably isn't powerful enough

2. The other option would be to keep the 100 bucks since my current battery works just fine on my 430 rms amp. Still do the big three upgrade, but swap out my alternator for a high output model. However the prices for the HO alts are all in the 200's and by the time I finish this build I'm already looking at 1800 bucks and I'de rather not break the 2000 mark. Also im kindof clueless as to what amperage I'll need I know the amperage the amplifiers will need but I dont know what the car draws. So if theres a great alt that can handle around 1800 watts rms or so thats around 150 to 200 that would be a better option. Then I'de just use distribution blocks from the 1/0 gauge into the 4 gauge wires

When I had my buick I had two batteries and I think it put some stress on the little 105 amp alt. But gtps have 160amp alts from what I have read. So I would say 2 batteries so that way you can also listen to your music worry free when your car is off. If you don't have a gtp I apologize for my ignorance.

Mine only has an 105 alt.

I thought my 04 had 125 according to a rebuild shop but I read a few post in forums that said 160 so I'm not really sure

I'm running 2 battery's and 220 amp alt. They only real use of the extra bat is because I do a lot of demo's with the car off, I would go with a good alternator upgrade your wiring and you will have no worries at all.

First "1800 watts rms" isn't a real measurement. In the history of electricity has anybody ever seen "root mean square" anywhere besides car audio? That's because it doesn't make any sense and isn't a real measurement of ANYTHING.

Second, unless you're playing a sine wave there's no way in hell your amplifier will draw a steady current. Everybody knows my opinions: Extra batteries are stupid unless you're playing the car with the engine off. Higher output alternator is always the way to go and Big 3 is stupid unless upgrading the alternator...but that's just because you can't pull more than what's available through grounding. Blinking lights is mostly due to poor grounds.

Next...there's a guy on gpona who's gone to world competitions for spl and he gets 150's on stock alternator. I think he has 4 runs of 1/0 to mitigate any voltage drop issues; goes back to that stuipd math problem V=I/R

I know an amplifier will not draw a steady current, but for most people of typical knowledge and opinion there going to go by what the amps rating since actual power draw is always going to vary at any given time, and no amplifier will be 100 percent efficient. The jh1200 is sitting at 82% efficient and the polks are in the mid 80's as well but im switching as of now to the PA 330's and running them at 2 ohms since i can pick up the 330's for 45 bucks a piece and the pa 660 would cost me 100 each. So now were looking at 1600 rms.

For the battery a good portion of it is because that is what my audio shop is recommending plus im getting the stinger yellow top 1000 for 120 bucks i hate worrying about whether or not ill kill my battery if i shut the engine off. Its pretty embarrassing when your 2 grand system leaves you stuck in the parking lot. The second battery and an isolator will be a big help. Plus it will make wiring changes and amp switches easier.

Looks like ill probably be picking up the subs and ordering the amp as of tomorrow. So ill post some pictures of the subs soon. I've managed to get my hands on the RE SE 10D4's instead of the SEx subs. So mine were made in america and they will hold up a lot better than the cheaper looking Chinese made SEx subs.

You raise some interesting points when looking at it strictly from an electrical standpoint. I agree that V=I/R is the main formula when looking at it that way. Along those lines, the amplifiers power output is not necessarily a good measure of determining it's power requirements, because all amplifiers have different levels of efficiency when converting electrical energy into sound energy.

It's actually not as simple as "efficiency". Ever seen a read out of music?





Do you people really think that the voice coil on your tweeter can handle 10 "RMS" watts? If you send a 10 watts of heat at that coil the tweeter is done. Guaranteed. Do you think that your mid's coil can handle 25 watts of steady heat? Oh, and the term "pulling" power isn't just vernacular. The amplifier only draws the power it needs to accomplish the given job.

Watt is a measurement of heat. Because music is SO DYNAMIC there's no telling WHAT you're actually sending out of the amplifier. You can average the power draw over the course of music play to see what the amplifier is actually pulling but that's about it. I'll say it again, extra batteries and h.o. alts typically aren't necessary. The same way it's not necessary to have 1.2jigawatts to hit 150dbs(it's done with as little as 500watts). The same way you don't need lots of speakers to hit 150dbs(a 6.5" speaker accomplished this too). Btw, my single sub and mids are in the 130's sealed on a good day C weighted and in the 120's depending on the song.

I just want people to start questioning what these "professionals" are telling you. Because they typically aren't all that professional. Go ask those installers what they think of infinite baffle installations. They won't know what you're talking about. Ask them about isobaric enclosures and their purpose. They don't know. Bring up Aperiodic enclosures...comb filtering...time alingement/phase change...blah blah blah

Most of these people are just copying something else they saw. Does anybody know where the idea for capacitors came from? In a really old install in the 80's there was a man who was the epitome of car audio; he had an issue with the voltage regulator not responding quickly enough to the dynamics of the amplifier power draw. Therefore, his lights would dim. He added capacitance to the circuit that his interior lights pulled from to give the volt. regulator time to do it's thing without dimming the lights on that circuit. This raised his competition score. The capacitors weren't used in conjunction with the amplifier AT ALL. Now for whatever reason...people throw in a cap on the amp circuit thinking it fixes problems. NOPE! A well designed amp already has the capacitance it needs built in.

I'm not mad at anybody, just tired of misinformation. I think big 3, h.o. alts, wiring, extra batteries(typically used for spl burps n' such since engine is off) and caps are just plane stupid in majority of all cases.

Good grounds are HIGHLY under rated. Especially the choice for grounding locations.

Well ideally you want to ground to a giant piece of metal that can take a hit and is separate from the rest of the vehicle so ground feedback doesn't occur.

I just used the strut tower in the rear of the trunk. As long as my rpm's are up I don't have issues with dimming and that's while seat heaters are going and all the other electronics going too.

A lot of people just find random bolts and attach to that which is a bad idea. Sometimes there is a type of zinc alloy used for the seat bolts that will cause noise in your system. I don't know the reasoning I just know it does. Other times people grab bolts that are attached to a thin formed sheet but the bolt isn't making much contact with the metal at all. It's ok to use these locations but grab a large washer and remove some paint for better surface contact. The other issue people predominantly have is when they use two grounding locations that are touching each other. If you have noise in your system using this configuration it's the difference between two unequal grounding points interacting with each other.

A lot of times it can be trial and error. Another approach people take to avoid multiple ground points interacting is creating a single point source ground that extends back to the battery. Radio, amps, everything grounds at the battery in those setups. But upgrading your grounds in the engine bay are a very good idea at that point. I added a 8awg wire to my stock grounding at the battery. It's a little long but it's more of a "feel" accessory I guess?

I know...it's dirty, shatap. I used 4awg for my power wire(not hooked up in the photo). It has run two a/b amplifiers simultaneously that were fused from the factory for a total of 170amps. The output was ~"2000 watts RMS". The wire never became warm to touch. I don't think I ever really pulled more than about 35amps continuously either.

I recently measured my newer install which would amount to ~"1200 watts rms" and 80amps fused and it came to around 110db A weighted and 120db C weighted. The new amp is a 6 channel and class D.

I agree with whats been said. It is always hard to tell what the amplifier draw will be for any song or amplifier setup. Usually if your running your amplifiers bridged (usually 1 or 2 ohms) the efficiency is going to be quite a bit less then what is stated. Anyhow, for that kinda RMS power, I would upgrade the alternator and not get a second battery. A second battery will do nothing for your cars electrical system except let your stereo play when the batteries arnt being charged. The stock alternator doesn't produce the kinda amperage your system requires, so i would upgrade the alternator.
Good Luck.

Sounds like a capacitor to me. How do they describe it's function?