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Old 10-15-2003, 08:00 PM   #1
Scooby Newbie
Member#: 40765
Join Date: Jul 2003
Chapter/Region: South East
Location: Goose Creek, SC
2003 Impreza WRX blk
308.5 awhp

Default low voltage during idle?

I have Morette head and tail lights and about 2000w of stereo equipment. I recently installed the apexi S-AFC II, AVC-R , and Turbo Timer. When the WRX idles the TTs voltage meter reads around 11.9-12.5 which is very low. I have a 5 farad cap for the stereo but i think that with the addition of all the aftermarket lighting/electronics my battery may be overtasked due to the sock alternator. I am in search of a higher output alternator, I would really appericate either a link to buy one or a manufacturer/part #. I have seen annodized ones before but never for the 03 WRX, a blue one would be cool and it would match my engine bay. thanks
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Old 10-15-2003, 08:07 PM   #2
Trust no one
Member#: 11170
Join Date: Oct 2001
Chapter/Region: Tri-State
Location: NYC
02 WRX
15 WRX/05 GTO


The WRX alternator is rated at 75 amps which is less than the 90 rating of the RS and other Subaru alternators. Unfortunately the cases are not the same so they're not interchangeable.
The output does become marginal at idle and with a heavy enough load the alternator will max out and the battery will begin to discharge.
At the very least replace your battery with an Optima which will tolerate the load much better than the stock one.
As for upgrading the alternator there have been some discussions on it, but no registered vendors have yet stepped forward to offer this service.

As for the Morette lights there is no reason they should increase the drain on the electrical system unless you have replaced the bulbs with higher than stock wattage ones, or you use the high beams all the time (which in the Morettes also keeps the lows on).
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