Dmak

I had to change my battery recently and I have been noticing that my voltage drops everytime I turn on the A/C, headlights or my stereo system.. I did some testing with a voltmeter at the battery and these are the numbers I am getting:

- battery with engine off 12.57
- engine on with headlights on 13.43
- engine on with a/c on 13.25
- engine on with radio on 13.40
- engine with everthing on 13.02

Seems like my alternator might not be working properly or something else? Anyone have any experience with this?

Kris Hansen

If it IS the same as it is at the battery, you might try to replace the brushes..If that does ont work, you need a new alternator..

If it is NOT the same, check for a broken wire, or loose connection at the battery or alternator.

HDClown

voltage drops when you add more load, that's 100% normal.

Dmak

Do you get the big voltage drop when you turn on your A/C?

eMKay (BFLO)

It's possible you have a bad alternator. Normal engime on voltage should be above 14

HDClown

so the lights reading could definiately take it down that low if they were HIDs, and the A/C and a stereo systems (assuming with an amp) will definiately be in those lower 13s with just the car idling. They seem perfectly normal to me.

HDClown

yes, it will go back up when your actually driving, but idling, its a noticeable drop

Dmak

I always noticed that the voltage is above 14.+
I do have HID's and from my knowledge that should make a difference because its should be drawing less power.. Yes I have an amp, and I think I should ad a cap to it.

But the voltage should be somewhere over 14??

Auditude

Worry when the voltage drops below 12.57 with the engine running.

nick n

on the capacitors in my trunk read:

14.1 ~ 2 w/car (with or without radio on).

13.7 ~ 8 w/ engine and headlights on

12.5 ~ 7 w/ car off

That's all the info I have

HTH.