Alternator/ battery

[Hosh1234]

Hi I have 2012 genesis 4.6 and it keeps dying on me. I bought a new battery and it died again so I’m thinking it’s the alternator.. I bought a multimeter to check and the voltage went down fast. Also when I tried to jump it off it died when I took the cables off. I’m also concerned that I bought the wrong group size.. I bought a h8 and I think it needs a h9.. would that be why it’s acting weird?

 

[joegr]

That does sound like a charging system fault. It's probably the alternator, but there are other possible causes too. While having a smaller battery isn't a great idea, it's not enough to be causing your problems.

 

[mikec]

I'm assuming your dash battery warning light is NOT lit; if it is lit that would indicate the alternator or its internal voltage regulator or associated wiring are kaput. Do you see that warning light when you push the START button twice without holding the brake pedal down - i.e. the dash light bulb test mode? If not, the bulb is bad and thus you wouldn't know the alternator is bad as well. On Tech package vehicles, having the stereo ON when the alternator isn't working will make the nav screen display a warning message about running the system with the engine off; this message pops up every few minutes and then disappears.

How fast does the battery discharge? Minutes, hours, or a day or two? If it won't hold a charge overnight, the battery is bad or something big in the car is staying ON. Alternators with bad internal diodes can drain a battery overnight as well. NAPA and many auto/battery shops can test alternators; some can even test it while it's still installed in the car. An alternator with a bad diode typically will have a lot of "ripple voltage" in its output which manifests as a significant AC voltage reading compared to normal.

Open the ski pass-thru in the rear seat so you can eyeball into the trunk area. Make sure the trunk light isn't stuck ON.

Another issue: on the underside of the hood there is supposed to be a small rubber bumper that mates with the pushbutton switch in the plastic cover plate along the driver side fender, about half way between the windshield and headlight. This switch is part of the car alarm system. When the rubber bumper is missing, the pushbutton sits in the "hood is open" position so a) the alarm never arms, and b) all of the high-power electronics (NAV, stereo, etc.) stay in STANDBY mode rather than fully powering OFF. STANDBY will kill the battery in a day or two. There is a TSB for 2009 model year cars that had a too-short bumper that lead to similar symptoms. See if your car is missing the bumper. TSB 09-BE-026 shows a picture of where the bumper should be.

mike c.

 

[Gunkk]

Hi I have 2012 genesis 4.6 and it keeps dying on me. I bought a new battery and it died again so I’m thinking it’s the alternator.. I bought a multimeter to check and the voltage went down fast. Also when I tried to jump it off it died when I took the cables off. I’m also concerned that I bought the wrong group size.. I bought a h8 and I think it needs a h9.. would that be why it’s acting weird?

Group H8 is the correct size.

If you have a red battery light on your dash, then alternator failure is most likely.

 

[toxicavenger70]

With it running check the alternator to see how much voltage it is putting out.