battery output

I have been watching my volts lately on my 89' rex si and I've noticed that the volts fluctuate in a strange way. During the day when the lights and accessories are off the volts sit at 12.2 during idle after warm up and don't increase too much while I'm driving. What makes the problem weird is when I turn my lights, or heater fan on - the volts shoot up the normal 13-14volt range. My alt is new and when the volts started dropping below 12 volts on me yesterday, I bought a new battery cause the old one looked really old and it almost died on me after listening to my stereo without the car being started for about 10 minutes. I'm baffeled by the cars behaviour cause I have a 700 watt system in it and the volts always go below 12 now unless the lights or fan is on, lol...does this sound normal to anyone?

P.S. the volt-meter is built in to my Pioneer deck and its always given me accurate readings in the past

I have a similar problem, when my car warms up sometimes the alt makes a squeeking sound, but if I turn on enough electrical components (lights, stereo,fan) then it quiets down, I have no clue on the volts, dont have a meter.

I have a similar problem, when my car warms up sometimes the alt makes a squeeking sound, but if I turn on enough electrical components (lights, stereo,fan) then it quiets down, I have no clue on the volts, dont have a meter.

I'm thinking.... Maybe when you turn on the extra's you are adding a better ground and that is making the voltage go up. Check your grounds and maybe add one or two.

Also with the car off you should see 12 volts, Running you should see 13 - 14 volts. also the book says to check the mounting bolts for the alt including the bracket, it's a ground too.

With your stereo/system you might be over taxing the alt, maybe time to upgrade to a higher amp alt.

I have a similar problem, when my car warms up sometimes the alt makes a squeeking sound, but if I turn on enough electrical components (lights, stereo,fan) then it quiets down, I have no clue on the volts, dont have a meter.

like the one said above and could be your bearing slowly on the verge of going out???...cause the faster it spins the hotter it gets and it wont squeal anymore...

or it could just be too loose or too tight. how old is your alt belt bigtex? mine was squeakin bad for a while so i went a got a new one for like 8 bucks from autozone. your belt might just be losing its tension due to cracks and belt aging. it only takes you about 10 mins to put in the belt and you dont even have to jack the car up, just crank the steering wheel so you can loosen the lower alternator bolt and get the adjust bolt from the top with a ratchet wrench.

im not sure how old it is, but Ill try a new belt thanxx

With your stereo/system you might be over taxing the alt, maybe time to upgrade to a higher amp alt.

Do you know where I can find higher amp alternators? :frown: I need to get 180-200amp

Thanx smoghog....

I took my alt bracket off and ran a power wire brush to it to clean it up, cleaned up my mounting bolts...problem gone! hehe, who knew it was something so simple...

Thanx again
:wink:

Thanx smoghog....

I took my alt bracket off and ran a power wire brush to it to clean it up, cleaned up my mounting bolts...problem gone! hehe, who knew it was something so simple...

Thanx again
:wink:

What do you know, the damn manual did some good. I am sure someone read that and thought it was Bull&%$#. I installed a grounding kit and ran a groundwire straight to the alt, and everything else.

It really did help in my case anyways...thanx again smoghog....kudos on the idea of running a ground to the alternator - I'm gonna do that to just as a precaution..I wonder if having a bad ground on your alternator is the reason most high wattage stereos always seem to blow alternators on older cars? I know big amps kill the output on the alts...but still maybe making sure you have a good ground there would help prolong them a bit...Anyhoo, thanx again!