Joined: Aug 02, 2006
Posts: 705
Location: McLean, VA, USA
Posted:
Sat Nov 18, 2006 1:28 am
Is it me, or other people have similar experience? Whenever I'm replacing alternator, it’s a pain in the ass to put it back into the bracket. I mean I literally spend hours on this sometimes.
Hmm, I'm not sure as I've never replaced an alternator before. To be perfectly honest, I'm not entirely sure I know the exact point of one, apart from drawing the engine's energy via a belt and turning it into electricity to charge the battery and in turn power the electrical system. Is this accurate?
I was actually considering getting a new one, if I decide to put more audio equipment into the system. I think I'm going to be peaking around a 300amp draw on the battery, running about 200rms. You thoughts? The stock alternator should handle it fine, methinks, but it would give me a little more power to work with.
I actually forgot to mention I have an aftermarket battery, a Stinger SPV35 I think, and all the wiring to the amps is done in 0awg so I shouldn't be over-pulling through my wire.
Joined: Aug 02, 2006
Posts: 705
Location: McLean, VA, USA
Posted:
Wed Jan 10, 2007 5:03 pm
Yea, your assumption is almost accurate. Just one small detail - alternator is used to power the system AND charge the battery. Battery is a backup source of electricity, which should not be drawn upon when engine is running.
And to the best of my knowledge your stock alternator is capable of around 70 Amps max, and I believe you will have a very hard time trying to find 300 Amps alternator to fit your car. And I can hardly imagine why would you need one? You are not going to install amplifier in a range of kW, are you?
When I think about it, it's all about limiting bottlenecks. A 0awg wire will handle ballpark of 384amps of current continuous, so that wouldn't be one.
A midrange amp pulling 300wrms would need about 20amps continuous, as 300wrms/14.4volt = 20.8333amps. A sub amp pulling 1500wrms would need about 104.166amps continuous as 1500wrms/14.4volt = 104.166amps.
assuming my amps were running with almost maxed gains, with loud dynamic music, I would pull about 120amps continuous, and I would WANT to be able to peak as high as double that (240amps, 260 to be safe.) If I wanted to add a second amp, I'd want as much as 220ampRMS -- peaking at 340/360ish.
Does that make any sense to you? Everything is theoretical, as music is dynamic, never static the way a test tone is, and you never play your music at max volume, and it's not the best idea to always run amps with the gains maxed on high volume, as this could cause clipping... but you get the idea.
Theoretically, I would have 4 2000wrms subs, each powered off a 2500wrms amp -- and with the voltage drop taken into consideration and everything maxed on a test tone -- I could peak as high as 650amps. Of course not counting a pair of really bright headlights that suck an amp or two apiece, and whatever else electrical...
Joined: Aug 02, 2006
Posts: 705
Location: McLean, VA, USA
Posted:
Wed Jan 10, 2007 6:06 pm
Basically, for my uneducated ear, 200-300W sound more than enough to alienate all of your neighbors who have little kids. I can't even imagine what one plans to do with 3kW. Crashing surronding houses?
WRMS is watts RMS, meaning Root Mean Square - more commonly known as average/continuous. A speaker can handle 100wrms before getting dangerously hot, but it can peak any where up to a few times that wattage for a few seconds.
A home stereo ie theater in a box system - 5.1 surround with dvd player and sub - would prolly run between 300-600wrms. Keep in mind that fills a room of your home with acceptable sound. A car is like 1/5th of the space, and it is mostly sealed. That's how peeps can get 180dB readings.
Joined: Aug 02, 2006
Posts: 705
Location: McLean, VA, USA
Posted:
Thu Jan 11, 2007 1:34 am
Nice toy
It took me a while to understand that wrms thing, but now I'm on the same page with you. Yes, if you want to have that much, you will need to install roughly 350A alternator, providing you will use your system to its full power potential.
Frankly, this looks insane to me. I just googled for high output alternators, and I'm pretty sure you will not be able to fit neither single nor a bunch of modular units into your engine bay. Unless you install second engine in the trunk just for that, I don't see how this could be done, sorry
EDIT: Since the thread is now all about car audio and I just got a forum for that, moving it here
What do you mean a few modular units under the hood? For the most part, the systems are done up in the trunk/back of the car. Is this what you meant? IE - amps, subs, wiring, spare battery etc?
Joined: Aug 02, 2006
Posts: 705
Location: McLean, VA, USA
Posted:
Sun Jan 14, 2007 9:04 pm
I meant several alternator working together. Cause the single unit capable of providing 300+ amps would be around the size of 12 inches in diameter and 18 inches long (according to what I was able to google), and no way that monster could fit into your engine bay
I'm probably out of my depth here, but doesn't the spike of current needed for the bass beat rely on the battery and sometimes a capacitor for a source of low internal resistance power? I've always thought the alternator only had to provide the average energy used by the system, not what the amps would draw 1/10th the usage time
(I'll translate later if that's gibberish, I haven't gotten coffee in me yet)
Yes, I believe that is more or less correct. However capacitors are sort of a band-aid fix for a component (sub) not getting enough current. A decent aftermarket battery, some fat wiring, and decent connections should remove all need for a capacitor, as far as I know.
OOOOoooo.. but they come "neon lit" how could you go wrong??
honestly though, I would think a capacitor would end up lengthening the life of even a high end battery just by moderating the draw on it. (unless even the momentary spikes are well within the safe output level of the battery)
...now I want the 50 farad cap I found. not for any good reason mind you... just to play with. Its not neon lit though.
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Crashing surronding houses? 
