Welcome to the North American Subaru Impreza Owners Club Tuesday July 29, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC General > Car Audio, Video & Security

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 02-03-2003, 11:34 PM   #1
ShadowIMg
Scooby Specialist
 
Member#: 31519
Join Date: Jan 2003
Chapter/Region: MWSOC
Location: Evanston, IL
Vehicle:
2009 Legacy spec.B
2001 2.5RS Coupe

Default Alternator, Alternator, Alternator

Does anyone know good detailed ratings on the alternator output of a 2003 2.5RS? I see it listed as a Mitsubishi 12v 75a alternator, but this doesn't speak to the varied outputs at different rev levels. Is 75 the ceiling, or the floor? Also, does anyone know how much there is to play with on a stock car with fog lamps? I'm wanting to put a JL 300.2 and 500.1 on there, powering MB Quart QSD 216s and a JL 10W7 in a Prowedge, with a 5 farad cap in there to control the burst draws, but i'm wondering if i'm already going to be way over alternator capacity at idle. I suppose I can hook a DC voltmeter up and check the idle running draw with various devices on, but i'm hoping someone else has already gone through all this fun.
* Registered users of the site do not see these ads.
ShadowIMg is online now   Reply With Quote
Old 02-04-2003, 12:29 AM   #2
Will98RS
Scooby Newbie
 
Member#: 15816
Join Date: Feb 2002
Location: New York
Vehicle:
1998 Impreza RS
Black

Default

not to highjack but i have a similar question.

i want to put in two rockford fosgate amps the 500x and the 500bd, i have a 98 RS.

basicly my question is how does one know when one's electrical system will be overburdened. this might make a good sticky at some point.

thanks
will
Will98RS is offline   Reply With Quote
Old 02-04-2003, 01:45 AM   #3
Sobelizard109
Scooby Specialist
 
Member#: 10302
Join Date: Sep 2001
Chapter/Region: NESIC
Location: CT
Vehicle:
2005 GT WAGON
SILVER

Default

how much are high out put alternators and where can i get one?
Sobelizard109 is offline   Reply With Quote
Old 02-04-2003, 01:16 PM   #4
TXBlueBeast
Scooby Specialist
 
Member#: 24494
Join Date: Sep 2002
Chapter/Region: TXIC
Location: McKinney, TX
Vehicle:
2008 Prius

Default

you should talk to 'ruiner'. he got his alternator rewound....
here is a quote from him from a thread a while back
"The stock WRX alternator is 75 amps. This sucks. Most cars are ~90-100 amps. If you plan on any subs at all, and you want to keep your electrical system forget it. I just ordered an OEM alternator and am having it rewound to 165 amps."

Hope that help you a little bit
TXBlueBeast is offline   Reply With Quote
Old 02-04-2003, 03:20 PM   #5
subaru mike
Scooby Specialist
 
Member#: 30749
Join Date: Dec 2002
Chapter/Region: Tri-State
Location: west milford nj
Vehicle:
2002 wrx

Default

Are you going to rewire your car? I am thinking of doing this but i am worried that i will fry the wires....like when you use 100 watt bulbs in the stock wireharness...let me know
-mike
subaru mike is offline   Reply With Quote
Old 02-04-2003, 04:13 PM   #6
ShadowIMg
Scooby Specialist
 
Member#: 31519
Join Date: Jan 2003
Chapter/Region: MWSOC
Location: Evanston, IL
Vehicle:
2009 Legacy spec.B
2001 2.5RS Coupe

Default

I don't have any real reason to rewire the car, the audio equipment is direct lined and fused seperately. I simply need more power available off the alternator, as the fuse rate on the 2 amps is 40A and 50A respectively, so if you take their max draw at 90A combined vs a 75A alternator peak, then add the car electrics to it, should my heater turn on with my headlights we're probably talking 140A-150A. I don't listen to things at great volume, so I can assume safely 25A and 30A draw giving me 55A of draw there, but the lights and electrics still put me way over 75A, which means dead alternators and batteries. I'll have to go digging around and see what I can find I guess. I sent a request into Subaru for an OEM high-output alternator. They used to put nice 110-120A alternators on the older models, we'll see what they say. Other than that, I believe Bosch makes a lot of aftermarket higher current capacity alternators. The rest of the wiring can stay just how it is, save probably the battery and the battery<>alternator lines. No added draw is being placed on any of that circuitry.
ShadowIMg is online now   Reply With Quote
Old 02-04-2003, 04:43 PM   #7
Styley1
Scooby Newbie
 
Member#: 32566
Join Date: Feb 2003
Chapter/Region: NESIC
Location: Ashland, MA
Vehicle:
1999 911 C2
XBL GT: Fenrick

Default alternators

I recently spoke with a tech from Esoteric Audio (the guys who make Street Wires and some other decent equip) about the situation.

I am planning on transplanting the system from my integra into my WRX:

RF 360a2
RF 201S
AudioControl EQQ

Only about 300W total.

He said that it should be fine, and a 1F cap would be plenty (and a lot cheaper than a new alternator). With a 5F cap and the system you mentioned... I wouldn't think you would have much problem... just a shorter alternator life. You might want to give them or another audioshop (that doesnt' make alternators) a call. Hope this helps.
Styley1 is offline   Reply With Quote
Old 02-04-2003, 06:45 PM   #8
ShadowIMg
Scooby Specialist
 
Member#: 31519
Join Date: Jan 2003
Chapter/Region: MWSOC
Location: Evanston, IL
Vehicle:
2009 Legacy spec.B
2001 2.5RS Coupe

Default

Well, it all comes down to the numbers. The shop doesn't make alternators, it was just a suggestion, and a correct one.

Alternator peak = 75A, so you can assume at normal engine speeds we're talking 65-70A output.

JL 300.2 Amp fuse rating = 40A, so 40A max / safe levels 25A constant draw

JL 500.1 Amp fuse rating = 50A, so 50A max / safe levels 30-35A constant draw.

Bear in mind, *ALL* a capacitor does is help for quick peaks, if you're drawing over your alternator rating consistently, your capacitor is doing absolutely nothing for you, except possibly making the problem less apparent to you.

Even running 300W total, it's a numbers game. The 75A alternator is just not a lot, especially if you have fog lamps, and it's winter time. You can safely assume with your normal headlights and fog lamps you're running 20A of draw right there, add the heater on, and I have a hard time guessing, but it's not going to be less than 5A draw, which brings you to 25A load.

300W / 13.8V = 21A, assuming 100% efficiency on your amp(s). 75% is a more reasonable estimate, for a good quality amp.

so If we assume 75% efficiency on 300W output, giving you 400W draw at 13.8V (perfect, no drop) you're talking 28A draw peak. Which means you're still safely under 75A, and your capacitor will probably be enough saving grace for you. If voltage starts dropping below 12V, you might be drawing up to 30-35A.

Now we take 300+500W output amps, assuming both 80% efficiency

300 / .8 = 375, 500 / .8 = 625. 1000W @ 13.8V means you're hitting 72A of draw. Toss in headlights, heater, foglamps, headunit, basic electrical systems, and you can clearly see that 75A isn't going to cut it. Long driving times with the system on would outright kill the battery unless you turned it off and let the car run to charge it back up, and your alternator is going to go about once a year.

The recommendation to replace an alternator at that point is well founded, especially for those of you running lightened alternator pulleys! Beware, those make your alternator signifigantly less efficient.

If you don't like doing all these numbers, just check the recommended fuse rating for your amps. The 300.2 is 40A and the 500.1 is 50A, which means manufacturer specifies it's safe for them to draw that amount of current before they should be shut down. That's 90A alone, by manufacturer specs.

I am very open to suggestion on this though, especially real-world voltmeter testing. I'd like to see how these are holding up. I know someone said they've had to replace their alternator yearly running a single 800W amp. Something to keep in mind.
ShadowIMg is online now   Reply With Quote
Old 02-04-2003, 07:08 PM   #9
Krelkor
Scooby Newbie
 
Member#: 6630
Join Date: May 2001
Location: Waterloo, Ontario
Vehicle:
2001 GC8
black

Default

i talked to dominick over on termpro

im sure someone who does stereos knows who im talkin about...
one of the best alternator guys out there

he can get me a 160a in stock casing for 399
or he can go to 205 for 389, but its a little bit bigger

if i want to go custom i can go up to 280a

i think im going to get the 205a

his alts put out about 90% at idle.... so they are good stuff
Krelkor is offline   Reply With Quote
Old 02-04-2003, 07:09 PM   #10
NateDogg
Scooby Specialist
 
Member#: 6467
Join Date: May 2001
Location: philadelphia, pa, usa
Vehicle:
1999 Impreza 2.5 RS
silver

Default

i have the JL 300.2 and 500.1 and a one farad cap. stock everything else. my lights dim a little at idle but thats about it. the volt meter never drops below 12.5

Nate
NateDogg is offline   Reply With Quote
Old 02-04-2003, 07:19 PM   #11
ruiner
Scooby Specialist
 
Member#: 20784
Join Date: Jul 2002
Chapter/Region: TXIC
Location: Dallas, TX
Vehicle:
2002 Impreza WRX
WR Blue

Default

I'm actually having my alternator rewound to about 145 amps hot. That's all they were able to get out of the casing that the stock WRX is. Unfortunately there are NO aftermarket alternators available for Subaru vehicles that I was able to find so I had to have a stack and stator built custom for my vehicle. If there is any interest in a high output alternator similar to mine, send me a PM and I'll see what I can do. Ideally I would need a stock WRX alternator in order to do this, but if you cannot supply it, I can possibly come up with something of my own. I have one extra stocker at the moment, but it might be spoken for I'm not sure yet.

An alternator such as the one I could possibly supply, would be able to handle a stereo up to 2200 watts, as long as you used an Optima battery or similar.

Chad
ruiner is offline   Reply With Quote
Old 04-26-2005, 11:21 AM   #12
RodimusPrime
Scooby Newbie
 
Member#: 82118
Join Date: Feb 2005
Chapter/Region: MAIC
Vehicle:
2005 GD6 2.5RS
Crystal Gray Metallic

Default

Resurrecting an old thread....

Does anyone know for sure what the stock alternator output is on a 2005 2.5RS?

This thread claims it's 75amps, but I have read elsewhere that the N/A engines have a bigger alternator than the WRX's. Does anyone know?

Question part 2) Is a total of about 400W RMS too much for a stock battery / alt?
(That would be from a 90Wx2 amp for the front speakers, and a 200W basslink)
RodimusPrime is offline   Reply With Quote
Old 04-26-2005, 12:34 PM   #13
cgerald1
Scooby Newbie
 
Member#: 34144
Join Date: Mar 2003
Chapter/Region: NESIC
Location: Nashua NH
Vehicle:
2003 WRX Wagon
Blue

Default

Here is a site with formulas that look about right:

HO Alternator Calculations


When I get a minute I will review the calculations and try to apply this to our cars...maybe make a VB calculator if I get time.

cg

Edit: Another good formula site more formulas

yet another good link: How batteries relate to Alternators

Last edited by cgerald1; 04-26-2005 at 10:00 PM.
cgerald1 is offline   Reply With Quote
Old 04-26-2005, 07:05 PM   #14
TheMort
Scooby Newbie
 
Member#: 29371
Join Date: Nov 2002
Location: CT
Vehicle:
2002 Subaru WRX
Rally Blue

Default

Does anyone have any experience with these Alternators Almost double the stock 75A, for $320.
TheMort is offline   Reply With Quote
Old 04-27-2005, 01:02 AM   #15
Scoobyracer1
Scooby Newbie
 
Member#: 35114
Join Date: Apr 2003
Vehicle:
2002 WRX
Silver

Default

I have an AFTERMARKET ALT on my wrx...

150AMP alt that produces :

130 amps @ 1000 RPMS
150 amps @ 1667 RMPS (Hot Rating)

It produces around 180 AMPS cold (SAE)

Unfortunatly they arent cheap, but if you are doing a FULL blown install.... u may need one...

After everything is said and done you are looking at over $500 for a quality piece of equipment...


As for these: http://www.2kracing.com/product_info...oducts_id/2650

The biggest problem is there are no specs... IE what it REALLY puts out... and are they hot or cold ratings... When does the ALT achieve max power...

Mine is linear driven... Made to produce max power right away and stay there.... It doesnt keep increasing... (wound ones typically do this) IE go from 1000rpm idle 40amps.... 5000rpm 120amp (Cold)....

In reality it may be only a very small increase over stock... The only way to tell is with spec sheets...
Scoobyracer1 is offline   Reply With Quote
Old 04-27-2005, 10:07 AM   #16
RodimusPrime
Scooby Newbie
 
Member#: 82118
Join Date: Feb 2005
Chapter/Region: MAIC
Vehicle:
2005 GD6 2.5RS
Crystal Gray Metallic

Default

Ok back to my original question

Can anyone confirm for a stock 2005 RS - what is the alt output?

75A, like the WRX, or more? I have read differing opinions...
RodimusPrime is offline   Reply With Quote
Old 04-27-2005, 10:42 AM   #17
ruiner
Scooby Specialist
 
Member#: 20784
Join Date: Jul 2002
Chapter/Region: TXIC
Location: Dallas, TX
Vehicle:
2002 Impreza WRX
WR Blue

Default

The stock RS alternator is 75A. The only one that is higher is the STi at 90A, and I believe the Outback or Forrester may also use the 90A unit.
ruiner is offline   Reply With Quote
Old 04-27-2005, 11:09 AM   #18
RodimusPrime
Scooby Newbie
 
Member#: 82118
Join Date: Feb 2005
Chapter/Region: MAIC
Vehicle:
2005 GD6 2.5RS
Crystal Gray Metallic

Default

Thanks ruiner - exactly what I was looking for.
RodimusPrime is offline   Reply With Quote
Old 06-01-2013, 02:11 AM   #19
best1
Scooby Newbie
 
Member#: 268495
Join Date: Dec 2010
Default

I have a jdm ej207 v7, is the alternator interchangeable with USDM ej257? bc mine is shot, killed 2 batteries. I probably need a hi performance /high amp alternator
best1 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
WTB : An alternator...any working alternator RallyGuy2k TXIC Private Classifieds 3 04-29-2010 08:11 PM
wtb--timing idler pulley, alternator and alternator bracket skate enjoi MWSOC Private Classifieds 2 06-05-2008 05:42 PM
is my Impreza Alternator SO much more than a Legacy alternator ? IllNastyImpreza Electrical & Lighting 4 06-04-2007 01:06 PM
Relationship between alternator whine, voltage, and alternator health caterpill Electrical & Lighting 2 01-16-2005 06:15 AM
Music: Is there an alternative to the alternative?? O2-GGA Off-Topic 20 02-05-2004 07:27 PM


All times are GMT -4. The time now is 11:08 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.