I have dual battery setup. With engine off, battery level is exactly in the middle line (between the 0 - 18v scale). Upon startup with no A/C or other electrical accessories, the battery needle slowly rises and based on my calculation of the gauge, it sits around the 12v level.
This rising behavior from 9v to 12v is normal, right?
Now, when I turn on the A/C or heater or fog/head lights, the needle dips a little bit - probably around the 10-11v level. And on the A/C, the fan seems not be blowing more air as if it's lacking juice. When I turn off the headlights, needle goes back to its normal level and blower blows more air.
Now, this behavior is not normal, right?
What is probably the defect here: battery or alternator or both?
I don't have any crazy idiot lights on my dash right now. Batteries are about 3 1/2 years old from PO.
I did search but did not get something related to battery gauge fluctuations.
As usual, hope you can help I would know what needs to be checked/R&R.
This rising behavior from 9v to 12v is normal, right?
Now, when I turn on the A/C or heater or fog/head lights, the needle dips a little bit - probably around the 10-11v level. And on the A/C, the fan seems not be blowing more air as if it's lacking juice. When I turn off the headlights, needle goes back to its normal level and blower blows more air.
Now, this behavior is not normal, right?
What is probably the defect here: battery or alternator or both?
I don't have any crazy idiot lights on my dash right now. Batteries are about 3 1/2 years old from PO.
I did search but did not get something related to battery gauge fluctuations.
As usual, hope you can help I would know what needs to be checked/R&R.