[Justin Mciver]

when I got to start my car in the morning, my voltometer reads about 10.5 volts. but the car fires right up.
then after driving on the freeway for a min or two the voltometer slowing creeps up to 17.5 volts.
it stays that high unless I turn on my stereoor electric fans. the fans cut it down to about 15volts and the amps for my stereo cut it down under 14 when the woofers hit.

I can watch my voltometer bouce from 17 to 14 whith the beat from the woofers.

is this normal?
do I need a bigger battery?
is my alternator bad?(had it checked at kragen they said it was good)
anyone have any Idea of what would cause this?
thanks


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Justin McIver
Sacramento CA
66-454-th350

 

[Gene McGill]

TURN YOUR STEREO DOWN!!! Problem solved.

Do your headlights dim with the thumps, too?
A friend of mine took care of this by putting in a 90-something amp internally regulated alternator.

 

[Justin Mciver]

I just took it for a drive and it Idles below 12volts, is at about 12.6 at 1500rpm, and sometimes doesnt get past 13.5volts.

 

[1BADS72]

Sounds like you deep cycled the batt and its not recovering well. Take the car to a parts place that can load test the batt. Also- did they check your alt on the car or off? Most bigger parts places have a roll out machine that can test the batt, alt, and starter load on the car. Lay off the big bass until you can get a capacitor for your amps. 1 farad for every 250 watts. Remember that when the motor is running, the alternator has to feed the whole car along with maintaining the volt level in the batt.
I used to run an audio place, now I run a parts place, so this is my "blue in the face" topic. Email me direct if you need more info.

later

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1BADS72
Robert Anderson
pages.hotbot.com/photo/1bads72/
[email protected]
THE HAPPY LITTLE TYR FRYR

 

[Havoc]

I feel your pain. I had 4 subs and 1200 total watts of amps in the trunk of my 71 Malibu. I had to upgrade to a 75 amp alternator and that solved the headlight dimming problem.

FIY, a voltmeter does not actually measure voltage, it measures the current through a resistor of a known value, and then the voltage is "calculated" using the formula V=I*R. That means that when your subs hit, they are actually stealing current away from the rest of the system, not voltage. A high-amp alternator will fix this, as will a capacitor. To tell you the truth, I'd rather spend $100 on a nice, chrome 100 amp alt. than on a cap. Dollar for Dollar, a new alternator is a better value.

-Havoc (Basshead/electrical engineer)

 

[Wes V]

Justin;

If your voltmeter is correct and your system is hitting 17.5 volts; have the regulator checked!



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Wes. Vann
Technical Reference & Wagons sections
Gold Member #5

 

[Justin Mciver]

thanx for all of your help.
im going to order a 100amp alternator today.
my regulator is brand new.