*split* HO alt discussion

From the H.O's car?

















Man that was a bad joke. So here's a good one.

Two blondes are walking in a forest when they come upon some tracks. One blonde says, "Those are deer tracks". The other one says "No, those are bear tracks". They go on arguing. Three days later they were found dead, having been run over by a train.

What do you call a smart blonde?
A golden retriever.

 

I reccomend dominic. I have heard VERY good things about Dom.

However, I ask why? Pardon my ignorance as it has been a while since I looked, but what amps are you running? Most cars nowadays should have plenty of power to run them. I don't recall the amps being all that big. Maybe a magic 3 upgrade is in order...

I will look briefly, and maybe edit this .

 

I will stand by my initial observations. The Honda will have at least an 80 amp alt, most likely a 100 amp. The Z9000 and the Q4000 are exceptionally efficient AB amplifiers. However the Honda's power and ground Cables are tiny (8 Ga I believe).

Try a "magic 3" upgrade if you have light dimming, and even if you don't. That should eliminate any dimming issues, or resolve any concerns you may have.

 

Yea, i've been considering saving up for a new alternator myself... but if you think minimal dimming could be alleviated by upgrading the magic 3, then i think that might be a better alternative than spending $250 on a new alt. .

I'm gonna be in town for a short time this week Seth, i may swing by the shop if that's cool.

 

And bear in mind also that dimming isn't a problem.

It's simply what happens when your car's total electrical current demand exceeds that which the alternator can support. And it's usually just for a moment or two.

All that happens in that case is that the extra little bit of juice that's above and beyond [what the alternator could otherwise do solo] gets pulled from the battery...
And as soon as the exceeding current demand stops, the battery recharges that tiny amount of current that was drawn from it nearly as instantly as it was taken.

Inherently, when this happens, the whole car's voltage level drops from the 14.4v of the alternator, down to the 12v level of your battery.
And light bulbs are inherently not quite as bright on 12v as they are on 14.4v.

There's absolutely no harm in this, unless your rate of discharge exceeds your rate of charge.
In other words, your average current draw exceeds the alternator's current capability.

And as far as THAT goes, bear in mind that your average current draw factors in all the things like what volume level you are currently running at, the "duty cycle" of the bass in your music (for a subwoofer amp, of course), how far below the maximum 0dB reference recording level the bass is recorded at, even how efficient your subwoofer/enclosure/amplifier are.
And it couldn't be any more unrelated to the amperages of the fuses that are plugged into your amp. Those numbers are beyond meaningless. Disregard them.
Your average current draw will make those numbers look monsterous, and your peak current draw might even exceed them. Meaningless...

Really what does matter is your average current draw, and even for many SPL competitors with real high power in their car, alternator upgrades aren't a necessity.
Some like them because it allows them to maintain 14.4v at all times, but some find that the idle current is largely the same as their stocker was... most SPL competitors who run larger alternators have to rig up something to hold their RPM's up, above 2000 typically.
Which brings us to the other downside of high output alternators..
Higher output alternators will inherently put more drag on your motor...
Put another way, after you install a higher output alternator, your motor will put less horsepower.
They are also expensive... and can you say that the money for the alternator might not better be spent elsewhere?

I'd only recommend an alternator upgrade if a real need is identified... (and light dimming isn't, really)...
AND after you've exhausted upgrading and solidifying the REAL fundamental foundation in your car's audio electrical system.. the power wiring. Might include the "magic 3", batteries, caps, good grounds, or others. It's mostly on a case-by-case basis...

But I think my strongest point would be to think of it this way:
By the point your average current draw is exceeding your alternator's current capacity...
Your output levels should be so deafening as to cause pain and damage, across the whole frequency spectrum.
If they aren't, it's not the fault of your alternator... you've got some system inefficiencies to resolve, probably as related to installation, or enclosure. B)

 

This may be a dumb question, but when the voltage drops from 14.4 to 12, and assuming your amp does not have a regulated power supply, would you not see a drop in frequency response in a certain area due to a loss of power to the speakers? I agree that by the time your lights begin to dim, the volume levels are fairly high, but I believe i have an exceptionally weak charging system because i do not experience the pain you speak of when my lights begin to dim ....i'm fairly certain my hearing is perfectly fine.

 

lol...
What I'm saying is, if you have so much power that you do seem to need to upgrade the alernator, it's likely that you could have gotten more output from the woofers without the massive quantity of power.
"Lights dimming" is a long way away from "needing upgrade"... so I can understand your not being in that "pain" threshhold.

And I know of lots of people who are running so much wattage, without fully realizing the real output capability all that wattage has... but all the while obviously still paying the full penalty of having all that wattage.
In other words.. they could have gotten the same output with much less power. B)

Most decent sized amps will draw enough instantanious current to cause light dimming on large bass hits.
But that's still a LONG way away from needing to upgrade your alternator, because your average current draw has exceeded your alternator's output capability.

As far as your other question:
The difference in acoustical output from 14.4v to 12v, as far as what your amplifier puts out, will be below your threshhold for hearing.
Bear in mind this is somewhat related to how regulated the power supply is...
But also, remember it takes a 4x increase in power to effect a 2x increase in output... point being, a much more dramatic difference in power is required with respect to output. So, the tiny decrease in power won't effect much in terms of dB, in output.

 

Chris, I'm willing to bet your Xterra has over a 100 amp alt. Weak charging system? Definately not.

This is turning into a great thread, and I definately will respond later today. However, it is now 8AM and time to go to work ...

Of course it is cool to stop by, you know you are always welcome B)

 

Haha, i looked it up one time and i'm pretty sure it was 80amp....if you have something there at work to doublecheck that i'd be interested in knowing for sure.

This is a good thread, but someone probably needs to break it off into its own topic, as we've strayed pretty far from the original one .

I'm gonna try and stop by on Wednesday afternoon.

 

according to my Info they have stock 70amp (4cylinder) and 80amp(v6) alts

soo seth, how much are you willing to Bet :lol:

 

hehe...i got the v6

 

Hey, I've got what, a 70a alternator in my Civic?
And a battery that is literally 4" wide (no room to fit a physically larger one).
And I'm running an Earthquake PHD2 and PH2.5 in the car.
On a piece of 4 gauge, nonetheless. :lmfao:

See, I wasn't intending on actually keeping them in there... I suppose I'll get my Audiopipe 1/0 gauge kit in there eventually! :lol:

Anyway, I'll admit to needing to replace my battery annually.. but honestly this year's demise was largely due to my parking the Civic for the winter (as I do every year), without disabling the alarm or disconnecting the battery. Which isn't a nice thing to do to your battery for several months.

Given THAT much current draw potential, you'd think the situation would be much worse, reading what you do on the forums though, wouldn't you?
Largely, these "you need to... "scenarios are exaggerated, IMO. B)

I personally try to initially install something that seems reasonable to begin with (except power wire, I'll default to "overkill" whenver possible there!), and then upgrade as I actually experience symptoms.
It's honestly too complicated to predict... much less entertain amatuer "You need to have this.. and that..." comments.

 

I only have a 500w amp and I need 5 200 amp alternators

 

The 4 cyl has a 70 amp alt and the 6 cyl has a 90 amp alt. Both ratings are at 12 volts. Your alt should deliver 77 amps at 1300 RPM at 12 volts (according to rebuild specs). Figure you are capable of about that at idle with 14 volts.

That is plenty for your install I should think.

 

I was thinking of splitting this, and Chris' suggestion pretty much sealed that deal. The topic is split.

 

Chris (Geo) brings up some good issues here, but I will disagree with 1 of them .

Typically high output alts will put out the same if not less than a stock alt. Many people who install HO alts are disapointed at the dimming getting worse after installing them. Also they will draw more horsepower to get them moving. Really the gains are typically noticed at ~1500-2000 RPM. And if you think about it, most street systems suffer dimming at idle (low output capability) not at cruise. Considering the fact that most HO alts put out less at idle than a stock alt, you can see they lack any of the target benefit when we consider when most people expect them to eliminate dimming at idle .

For that reason I always reccomend a second battery over an HO alt if the target goal is reduction of dimming at idle. Of course, I reccomend this only after the magic 3 have been handled . See, reserve capacity increases will greatly benefit the system in idle situations, moreso that the reactive load that an alt delivers. The battery is always there, the alt needs to see the current fluctuation to react (which is where our dimming occurs).

Now I will dissent...

When light dimming occurs we are actually doing damage to the electrical system. We are making the alt do more work to rebuild the current that has been robbed, and we are also giving it less voltage to produce that current. Now you see we are swinging a double edged sword . Also consider this, the greater current required throughout the system also adds heat, which is also going to increase resistance.

So when Chris (blkX) asks about shifts in transients, I suggest that yes, we will see sufferage in transient responce. For this reason a cap on front stage amps is IMHO acceptable (and this is only for front stage where it may be noticeable, I never suggest them for sub amps).

 

Well...
To be fair, that's not "damage", that's "use".

If the alternator actually wore out in some way, I'd consider that my opportunity to consider an upgraded output alternator..
But I still certainly wouldn't go big - if even bigger at all - primarily because of the HP loss that inherently accompanies it.

Now... who sells alternators with published plots of current capacity vs. RPM?
:huh: