Stock Alternator
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This is a discussion on Stock Alternator within the Interior Mods forums, part of the Tech & Modifying & General Repairs category; how many watts are you guys pushing with your stock alternator? im thinking about runnin a pheonix gold ti800.1 to ...

  1. #1
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    Stock Alternator

    how many watts are you guys pushing with your stock alternator? im thinking about runnin a pheonix gold ti800.1 to each of my 12w6s so a total of 2 amps.

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  3. #2
    Registered User Th3Franz's Avatar
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    I don't have a WRX yet but when I get one I'll be pushing 1800 W RMS once I install everything. If you don't wail on your system a lot, I wouldn't worry. But I plan to do some competition, so I'll probably get a beefier alternator.
    - F r a n z
    Bucky with teh lime powah!

  4. #3
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    Okay guys, here's the 'science' behind it. I'll be generous with my estimate.

    -WRX alternater = 75 amps
    -Max Voltage = 15V
    -BUT there are systems in your car that take up power
    So we'll say 65 amps

    -Power = Voltage x Current
    -Power = 975 Watts

    -amps are not 100% efficient. That means they require more power then they expend. The rest of the power is lost as heat.
    -amp efficiency = 70-85%

    975 watts * 80% = 780 watts RMS.

    Remember this is conservative. Your vehicle systems probably take more than 10 amps draw off of your power system. Anything more than 780 watts should require an upgraded alternator unless you only use it for a couple of minutes at a time. Or you can hook up another battery to store more juice...
    Former car: 2002 Cobb/Scoobysport stage 2 WRX sedan
    New ride: ???

  5. #4
    Registered User Th3Franz's Avatar
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    Yeah I'd have to say that is a very conservative estimate, even. Depending on if you have the A/C on, etc., I'm gonna guess that the current draw from just the engine is going to be higher than that. That's why I'll be adding a beefy battery and probably an upgraded alternator once I get a WRX.
    - F r a n z
    Bucky with teh lime powah!

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