Alternator swap

Ajhfootball · 02-12-2013, 09:36 AM

I have a 03 legacy L. My alternator isn't strong enough to power my Sound system. I have a couple options to help but I'm not sure what to do and what order so I can fix the problem while spending the least amount of money.
1.Big 3
2.HID lights
3.Swapping a alternator with a newer or larger sized on from a wrx or legacy gt
4.New alternator
I'm running a 12" sub with a 1000 watt amp (Sony xplod) and 2 kickers components with a 500 watt (lightning audio)
Could another option be buying a new 4 channel amp?

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Subulooni · 02-13-2013, 04:45 PM

Yu will jus need to buy a bigger alternator (higher amperage output). Yu can buy a rebuild kit for yur specific alternator. That would be the cheapest way out of it. Only if yu knw what yur doin when yur rebuilding.

Charlie-III · 02-17-2013, 03:00 PM

Higher output alternator. All the ones I've seen are "drop-ins", no modding needed.

I "think" the options are a 90amp or a 120amp. I use www.rockauto.com to compare parts/prices.

121jiggawatts · 02-23-2013, 08:14 AM

This is a common problem any time you start adding electrical load to your car.

https://www.dcpowerinc.com/vafproduc...L+H4&year=2003

That is DC, there is also Mechman, Ohio Generator, Tenny, and Iraggi off the top of my head.

You want to look at your usage or future usage in watts, so assuming your amps actually put out rated power 1000+500 = 1500 watts, you divide that by 10 to get an ampere figure, so you would need 150 amps from your alt for your audio system to not drain your battery.

You divide by 10 in a 12 volt system because your amps arnt 100% efficient, so for every 1 amp they draw they dont make 12 watts of power, D class amps can often be in the 80-90% efficiency range, where AB class (most commonly found in your muliti-channel amps) are in the 40-60% range.

If your headlights are dimming when your bass hits, try the big 3 first, If its just your battery draining down, then most likely you need a new or upgraded alternator.

cssubaru92 · 02-25-2013, 01:32 PM

I'm running 2 12" Rockford Fosgate subs with a 1000 watt amp. It killed my last alternator so I bought a 160 amp alternator for $190 brand new on eBay and haven't had any problems with it. I also have a 7" touchscreen headunit in the car.

02-12-2013, 09:36 AM	#1
Ajhfootball Scooby Newbie Member#: 339098 Join Date: Nov 2012	Alternator swap I have a 03 legacy L. My alternator isn't strong enough to power my Sound system. I have a couple options to help but I'm not sure what to do and what order so I can fix the problem while spending the least amount of money. 1.Big 3 2.HID lights 3.Swapping a alternator with a newer or larger sized on from a wrx or legacy gt 4.New alternator I'm running a 12" sub with a 1000 watt amp (Sony xplod) and 2 kickers components with a 500 watt (lightning audio) Could another option be buying a new 4 channel amp? * Registered users of the site do not see these ads.

02-23-2013, 08:14 AM	#4
121jiggawatts Scooby Newbie Member#: 345072 Join Date: Jan 2013 Chapter/Region: MWSOC Location: Ohio Vehicle: 2009 Legacy Black	common This is a common problem any time you start adding electrical load to your car. https://www.dcpowerinc.com/vafproduc...L+H4&year=2003 That is DC, there is also Mechman, Ohio Generator, Tenny, and Iraggi off the top of my head. You want to look at your usage or future usage in watts, so assuming your amps actually put out rated power 1000+500 = 1500 watts, you divide that by 10 to get an ampere figure, so you would need 150 amps from your alt for your audio system to not drain your battery. You divide by 10 in a 12 volt system because your amps arnt 100% efficient, so for every 1 amp they draw they dont make 12 watts of power, D class amps can often be in the 80-90% efficiency range, where AB class (most commonly found in your muliti-channel amps) are in the 40-60% range. If your headlights are dimming when your bass hits, try the big 3 first, If its just your battery draining down, then most likely you need a new or upgraded alternator.

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02-13-2013, 04:45 PM	#2
Subulooni Scooby Newbie Member#: 346952 Join Date: Feb 2013	Yu will jus need to buy a bigger alternator (higher amperage output). Yu can buy a rebuild kit for yur specific alternator. That would be the cheapest way out of it. Only if yu knw what yur doin when yur rebuilding.

02-17-2013, 03:00 PM	#3
Charlie-III Scooby Specialist Member#: 30669 Join Date: Dec 2002 Chapter/Region: Tri-State Location: 07456, North NJ Vehicle: 1998 Legacy 2.5GT Silver Sleeper Wagon	Higher output alternator. All the ones I've seen are "drop-ins", no modding needed. I "think" the options are a 90amp or a 120amp. I use www.rockauto.com to compare parts/prices.

02-25-2013, 01:32 PM	#5
cssubaru92 Scooby Newbie Member#: 348166 Join Date: Feb 2013	I'm running 2 12" Rockford Fosgate subs with a 1000 watt amp. It killed my last alternator so I bought a 160 amp alternator for $190 brand new on eBay and haven't had any problems with it. I also have a 7" touchscreen headunit in the car.