Am I misunderstanding something?

[JunkTitleGolf]

Ok my alt puts out 90 amps and my amp requires a 150 amp anl fuse. So if I was to run peak for any period of time wouldn't I be drawing 150 amps but only have 90 to offer or does the battery make up for the extra 60 amps? That is how I thought caps worked but from reading some post I have gained that all they do is even out the voltage spikes. Would that be recommended for my application? Also is there any companies that offer h/o alt for my 1995 VW Golf 2.0 8v? I have seen rebuilt alts that run at 120 amp but would that be suffiecent for me? Also the cost of that REBUILT alt is near 300...over priced or priced right. Sorry about the multi topic post here.

[ngsm13]

www.mean-green.com
www.ohiogen.com
www.h-o-alternators.com
Or check out Iraggi Alternators.

nG

[dave92cherokee]

The only time that your amp would draw near 150 amps is if everything in the system was cranked up as high as it could go and the amp was on the virge of overheating and long before that you would start experiencing problems with the system distorting. The inline fuse for the amp is mostly incase the amp shorts out which will protect the battery and the rest of the electrical system from shorting out as well. Most car batteries have about 600 cold cranking amps in reserve for starting the car so if your system suddenly draws 140 amps for a minute or two and then drops back down to only drawing 50 amps then that short time it will pull a little excess out of the battery and then when it drops down the alt. will replace that charge.

[PaulD]

your amp never pulls anywhere near that as a constant load ...... the battery will take over some IF the voltage sags below like 12.5 V. I would try it out and see before spending that kinda money on a new alt.

[NAVY IC]

one amplifier drawing 150 amps will get you into the 2000w neighborhood, that's a lot of juice.
Unless your a serious competitor or your system is a model of inefficiency, you'll rarely use that much output.
As far as experiencing distortion at higher levels, well lets just say that's why some equipment is considered high line.

[CBFryman]

morel ike the 1900w region assuming it isnt slow blow and the amp is extremely efficent.

It could be some type of uber sub tube amp with a maximum theoretical efficency of 20% being more i nthe 400w area assumeing your alt can keep up the 14.4v.

[NAVY IC]

I don't want to stray from Junk's original question too much but, were not talking about stereophile grade reference equipment. This is Kicker.
All were trying to do is amplify a (.5v-5v) rca signal about 100x's, which can be done pretty easily using about 30a and a 12-14 volt system.
Multiply that by 5 and now you're getting to what I originally posted about being a serious competitor.
like I said before...
As far as experiencing distortion at higher levels, well lets just say that's why some equipment is considered high line.

[CBFryman]

Ummm Maximum RMS ouput = Input Voltage*Maximum constant Current*Efficency

And that is if the amp is unregulated.

Assuming the amp is 90% efficent (maximum theoretical efficency for a Class D amp) and the alternator is capeable of holding 150a%14.4v you are in the 1900-2000w area. But, most Class D's are in the 70% area, most 200a + alternators may be able to stay constant round 13.5-14v. you are now looking at more like 1500w.

Also, many companies, especually hifonics, are using slow blow fuses which take up to 3min to blow at rated current and that is at either 20 or 36v...

My example about the space heater, i mean tube amp, is that going strictly on fuse rating will get you nowhere in ideas about how much power the amp can produce with out its theoretical efficency and input voltage.