Max Alternator Output

Juleous

What has been the experience been after stereo upgrades, I wonder how much power I can add to the electrical system before I need to upgrade the alternator and battery.

I had a previous bad experiece with an underpowered alternator, burnt through 3 before I put in a 100amp high output alternator. Didn't matter how much battery I put in the car I could never keep it charged when I ran the stereo. System was always in a state of discharge no matter what I did, new high output alternator no more problems.

Has anyone done this yet? What is the max stereo output anyone has put in a Z without upgrading? I will be running 1000watts on no 2wire. I hope it's not a problem IMO an alternator upgrade would be costly.

bigaudiofanat

I think most people and there z's have been fine with the audio upgrades they have done. But in the case that you have problems don't look to capacitors for help.

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Juleous

Funny you say that, such a 90's thing. Capacitors are best left for increasing phase shift, does anyone know the output of the stock Z alternator? Alternators tend to last longest when they are duty cycled not maxed out all the time, same with a battery IMO.

I remember blowing 40 amp fuses on some DJ Magic Mike Bass hits, crazy stuff eat 40amp fuses like nothing with those tunes.

DEpointfive0

I just ran across this thread.

LMAO!!! I just sent some of DJ Mike's stuff to someone to test out their audio setup

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Austin

Meh, I have never been big on caps. If you are going "reasonable" on a system, you won't need a cap. If you are going hardcore on a system, you need more than a cap.

Just my 2cents.

Unleaded91

I think iirc, the alternator output in the 370z is 150 amps. ...

I have a G35 coupe and iirc mine is 150 amps stock... I have 2 car amplifier installed. One with 920 watts rms and 150 watts rms..

imho, the stock alternator should be good if you're only gonna run around 1000 watts or so which is plenty. My system has been installed for almost 1 year now and I have never experienced dimming lights and stuff.

RonRizz

I am well over 1000 watts, and my voltmeter never wavers in the least.

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SouthArk370Z

According to CHG-27 of the 2009 FSM:
Hot output current (A/rpm)
More than 31/1,300
More than 122/2,500
More than 144/5,000

Regulated output voltage (V)
14.1 - 14.7
---

Assuming 14.5V, the alternator can put out between 450W and 2100W (give or take a few Watts).

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kwikymart711

Ironically just read this

Car Audio CAPACITORS: Why They DON'T Work

When I had one, it did stop headlights from dimming (in old 4Runner) but then again I had a yellowtop so I never had an issue.

From what I understand, it's all in the alternator and capacitors will actually increase the load and not help distribute it.

Jayhovah

Maybe I'm too far removed from college........ but I'm pretty sure there is a lot of false in that article you linked to. Not saying that we should be using enormous caps....but there is some technical stuff in that article that I do not believe is correct.

SouthArk370Z

A quick look at the wiring diagram* in that article tells me the author may not know what he is talking about. At the very least, he has poor proofreading skills.

But I do agree that a capacitor is not a fix - get a bigger alternator.


* capacitor in series, ground symbol used for power source

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radensb

Actually, it is showing the capacitor in parallel with the amplifier, which is correct. But I agree the diagram is not drawn very intuitively.

Capacitors are only of use in certain situations.

1. The car alternator has to already be up to the task to power the system.
2. The type of music that is played.

Typically, audio amps are rated for peak power, which is rarely ever reached. Most of the time, you are running RMS (root means squared) power, so keep that in mind.

The caps can help lower the instantaneous power demands of the amplifier from the cars power system during high current bursts (heavy bass bump) because it can supply the needed current faster than the battery can. (a cap is just a battery at heart and looks like an open circuit component once charged thus it doesn't draw anymore current but can supply it when needed) It IS still a load on the cars power system while it is being charged. If you have music that is playing heavy beats that are hitting back to back, over and over again, you will never give the cap time to charge, and thus render it useless (and additionally an extra strain on the power system).

The charge time for a 3 farad cap is not trivial. Lets assume that the resistance in the wire from the 12 volt battery to the 3 Farad cap is 0.5 Ohms. That means it will take 1.5 seconds to charge! If your resistance is 1 Ohm, the charge time increases to 3 seconds.

The point of a cap is not to supplement the power responsibility from the alternator. Rather, it is there to help regulate current spikes and voltage drops caused by the inherent rapid power demands that audio amplifiers introduce.

zakimak

Music is not a Sine wave and constant. That's why it has merit. The point about recharging time is rarely discuss and that's why it DOESN'T work as well in certain situation and it's an important point. Point being your source will always be the alternator and if you going beyond it's capacity ALL the time then no amount of batteries or caps will work. What we have here is an extension of the capacity of the Alternator given the scenario of music reproduction which means the demand is not constant hence headroom.

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zakimak

There's a point of using it. People tend to think it will solve the ills of their under-capacity system but it doesn't. The best case is always the Alternator no doubt. I think that's why it gets a bad rap - using it for the wrong reason. Remember all Amplifiers employ capacitors in their system (digital ones are slightly different) but it's the same principal - stabilizing the voltage rail. Whether that translate to better sound is subject for debate. Employing one externally is no different. When properly designed and implemented, it does have merit.

As for dangers in a car, nothing is more dangerous than a tank full of gasoline underneath one...

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Fountainhead

Capacitors are used in audio amps for
A: Bulk Caps (2200uF to 3300uF and up) Removing ripple from the high frequency switching supply that changes +12VDC to +/- up to 80VDC. (In parallel with high dissipation factor ceramics for the high frequency ripple).
B. They are used for storage for low frequency impulse power/peak demand. See 1 above.
C. They are used as AC coupling devices that block DC from stage to stage.
D. They are used as "Decoupling" devices to clean DC voltage so that active amplifier components have a clean power supply.

Scientifically I can't say that I support using large Farad value caps on the voltage rail of the +12V since the Battery can supply up to 350 Amps at cranking time on the car, so if the Alternator and the Battery can't handle the current load of the amplifier, then it sounds as if other have correctly recommended upgrading the charging/Alternator and the 12V reservoir/Battery.

I'm all for the smart marketing of the Farad add on caps, someone is making money and that's good old fashioned Capitalism at it's finest.