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    jacko's Avatar
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    is this bad for the alt?

    If you at a stoplight(in drive, rpm's around 700-800) and voltage meter hovers just above the red line on the low voltage sign, which looks like it shows about 10-11volts, with the AC on and the system at only moderate volumes. Does this mean my alt is dying, am I hurting my alt, or this not needed to be worried about. It's a '97 bonneville, 77,000miles, with stock 135amp alt(pretty sure it has one of the GM 135's or 105's, not sure). Estimating 65% effieciency for my 2 channel amps, my current draw from my amps is about 90amps at their rated RMS output(I have them on four ohm loads so I can't just figure using the fuses on the amps). However, if I'm in park or neutral, or driving(1000-1100rpms+) the problem goes away and it will hover around 13 volts. I just want to know if it's hurting the alt or not because i don't want to turn off my AC or turn down my system at every stoplight. thnx.
    Last edited by jacko; 07-12-2005 at 05:04 PM.







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    noob with an RS's Avatar
    noob with an RS is offline i poop on you



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    Re: is this bad for the alt?

    i think youre batteries not charging if anything. i think if the voltage is below system voltage (12.5 volts) the battery is not being charged? i could be very wrong.




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    Decipha's Avatar
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    Re: is this bad for the alt?

    sounds like you need a more powerful amp... the big 3 will help



    supercoupe enthusiast x9

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    Re: is this bad for the alt?

    Your alt's voltage regulator might be on the way out - or the alt itself is struggling to keep up with the demand. Although, I have a 135a alt (no A/C, however) and have never had dimming with 1.7kW of amplifiers...




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    ThatDude's Avatar
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    Re: is this bad for the alt?

    I have a question sort like this. In my car one day I was testing out how loud I can get, and I hit a bass note, and the battery light flashed for like half a second. Which means the alt wasn't charging the battery (94 Accord). I've never had it do this before, so I was kinda scared that I just screwed up my alt. I wanna know like the thread starter, does this hurt your alt alot, even though I'll try to never do that again?



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    Re: is this bad for the alt?

    If you put a smaller pulley on the alt it will spin at higher rpms at stop light and ruduce your idling voltage drop.
    Don't worry about the extra RPM's at highway speeds the voltage regulator will not allow the alt to put out more than 14.4 volts.
    Amperage output is reduced greatly at idle for ALL alternators, some are better built and will put out more amps at low RPMs then others.
    The peak amperage rating for alternators is at 2000 RPM which is well above idle, I bought an HO alt that put out 180amps at 2000RPM but only put out 40 amps at idle (I was pissed b/c i couldn't get my money back) to fix the problem I reduced the size of the pulley to increase the alts RPM at idle speeds (the belt would slip a bit though).
    If you get in the market to buy another alt be sure to check the output rating for the alt at idle to avoid any stoplight/idling problems.




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    Re: is this bad for the alt?

    some voltage regulators dont kick in and let your alternator charge untile above 1200 rpm. a lot of ford and other makers alts. will do this



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