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2018 G80 3.8L Battery Draining Overnight - Parasitic Draw?

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Chris P. · rep 0 · May 25, 4:37 AM · 1 replies · solved · Question

Vehicle: 2018 Genesis G80 3.8L

Hey everyone, I'm pulling my hair out with my 2018 Genesis G80 3.8L RWD. For the past few weeks, the battery keeps dying overnight. I've replaced the battery twice, thinking it was just old, but the problem persists.

I've tried checking for lights left on and unplugging my phone charger, but nothing seems to make a difference. It's especially frustrating when I need to get to work in the morning.

Could this be a parasitic draw? Has anyone else experienced this with their G80? What are some common culprits on these cars? Any advice on how to diagnose this myself before taking it to the dealership would be greatly appreciated.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 4:37 AM

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ClearTheCode admin answer:

A persistent battery drain on a 2018 Genesis G80 3.8L, even after battery replacement, strongly indicates a parasitic draw. This means a component is drawing power when the vehicle is off.

Common Causes of Parasitic Draw in Genesis Vehicles:

  1. Infotainment System Modules: These can sometimes fail to enter sleep mode, continuously drawing power.
  2. Door Lock Actuators/Switches: A faulty actuator or switch can keep a circuit active.
  3. Alternator Diode Failure: A failing diode in the alternator can allow current to flow from the battery when the engine is off.
  4. Aftermarket Accessories: Any non-factory installed electronics (dash cams, alarms, remote starters) are common culprits.
  5. Faulty Relays: A relay stuck in the 'on' position can keep a circuit energized.

Basic Diagnostic Steps You Can Take:

  1. Perform a Parasitic Draw Test:
    • Ensure the vehicle is fully off, all doors closed, and lights out. Let it sit for 15-30 minutes to allow all modules to 'sleep.'
    • Disconnect the negative battery terminal.
    • Connect a multimeter in series between the negative battery post and the disconnected negative battery cable. Set the multimeter to measure amperage (amps).
    • A normal draw is typically under 50 milliamps (0.05 amps). If it's significantly higher, you have a draw.
  2. Fuse Pulling Method:
    • While the multimeter is connected and showing a high draw, start pulling fuses one by one from the fuse box (both under the hood and inside the cabin).
    • Watch the multimeter reading. When the amperage drops significantly, the last fuse you pulled is on the circuit with the draw. This helps narrow down the problematic system.
  3. Check for OBD Codes: While a parasitic draw might not always trigger a specific code, a low voltage condition (P0562) could be present, or U-codes if a module isn't communicating correctly due to power issues.

When to See a Shop:

If you've performed the basic tests and can't identify the source of the draw, or if you're uncomfortable working with electrical systems, it's best to take your Genesis to a qualified technician. Diagnosing parasitic draws can be complex, requiring specialized tools and knowledge of the vehicle's electrical schematics. A Genesis dealership or a reputable independent shop specializing in European/luxury vehicles will have the necessary diagnostic equipment to pinpoint the exact issue.

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