Voltage needle dips when rear defogger on...?

[ravenp]

I just started noticing this the other day. When I turn on my rear defogger AND let off the gas, idle etc... the battery voltage indicator dips to about 10 from 13.5 and you can notice the interior lights dim.

When I give the car gas it goes back to normal.

Switch off the rear defogger and everything is fine.

Any ideas?

[silicuda]

This is normal.... the heating device for the rear windshield uses a lot of power, therefore the load dims the lights because the output from the alternator/battery is affected...

happens to me too, aftermarket car stereo setups with subwoofer/amp do even more, not only do they affect your interior lights/dash board lights from dimming but as the bass thumps your exterior lights dim too.... and you can see your power meter guage go up and down ... a solution to that is a 1/2 FARAD or 1 FARAD capacitor..

[ravenp]

Any thoughts on why it just started? I've had the car for 3 years.

[Blizzard96]

That happens to me except during a different situation.

If I throw the car in reverse (A4), the voltage dips and the headlights dim for about a second before it goes back to normal.

[Dewey]

Happens to me when I downshift. Bizarre.

[00swartz]

Watch your battery's health. It's winter, the strain on it is more severe and it may be trying to tell you something. Think summer with the Ts off!

[ravenp]

It sounds pretty common [img]smile.gif[/img]

It could be the battery getting weak. When my alternator went in the summer the tech told me to replace the battery but I didn't. I thought he was trying to gouge me.

It seemed fine through my racing days in the summer where there was a lot of on/off of the car...but now it's flaky.

Might need to break down and spend the $$

Thanks guys.

[silicuda]

Why it started could be because of your battery or alternator... things get old so they do not function as efficiently as before..

i wonder if putting a CAP directly by the battery would make all of these problems go away

[ravenp]

It might... but they're not cheap :(

[silicuda]

if you plan on putting a stereo in your car, it will be an investment you will have to make at one point.. if you go beyond 200W AMP for a stereo, it will dim your lights

[Blazzin Joe]

<blockquote>quote:</font><hr>Originally posted by Dewey:
Happens to me when I downshift. Bizarre.<hr></blockquote>

Me too :(

[Dewey]

<blockquote>quote:</font><hr>Originally posted by Blazzin Joe:


Me too :( <hr></blockquote>

Well here's two 2002 camaro's with this issue. Mine is about to hit 15K miles. If my alternator or battery is failing, I'm going to raise holy hell.

[ January 10, 2003: Message edited by: Dewey ]</p>

[Blazzin Joe]

<blockquote>quote:</font><hr>Originally posted by Dewey:


Well here's two 2002 camaro's with this issue. Mine is about to hit 15K miles. If my alternator or battery is failing, I'm going to raise holy hell.

[ January 10, 2003: Message edited by: Dewey ]<hr></blockquote>

I just rolled 17,000 the other day and its been doing this for the last few thousand miles.... :(

[toast]

Mine has done it since day one. It always bothered me. My volts are uasally spiked at around 14.5-15 on the gage and when i have the lights on and the heater fan on him, i turn the defroster on and the volts drop down to 13 and the lights dim and heater fan does not sound like it is running full strenth. Dealer said there is nothing to worry about since the alt is working fine and putting out the right amount of volts.

[grndlvl]

all is fine with this "problem" most times this happens is at idle when the alternator only puts out maybe 40 amps and the draw could be around 50 amps with everything on, as long as the as the voltage does not drop while at cruising speed everything is ok. If it bothers you step up to a high amp alt that has at least 70 amps output(hot soak) at idle.