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Persistent Battery Drain on my 2018 Genesis G80 - What's going on?

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Jason D. · rep 0 · May 22, 6:20 AM · 1 replies · solved · Question

Vehicle: 2018 Genesis G80 3.8L

Hey everyone,

I'm having a really frustrating issue with my 2018 Genesis G80 3.8L. The battery keeps dying, usually after sitting for just 2-3 days. I've already replaced the battery once, thinking it was just old, and the new one is doing the exact same thing. The alternator was also tested and seems to be charging fine when the car is running.

It's getting to the point where I have to keep it on a trickle charger if I don't drive it daily, which isn't ideal. I've checked for obvious things like lights left on, but everything seems to be off. Could this be a common issue with these cars? I'm worried about some hidden electrical problem.

Has anyone else experienced a parasitic draw on their G80? Any specific modules or components I should be looking at? I'm trying to avoid just throwing parts at it.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 6:20 AM

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ClearTheCode admin answer:

A persistent battery drain, often referred to as a parasitic draw, is a common electrical issue that can be tricky to diagnose. Given that your battery and alternator have been checked, it's highly likely a component is staying active when it shouldn't be, slowly draining power.

1. Diagnosing a Parasitic Draw:

  • Perform a Parasitic Draw Test: This is the most crucial step. Using a multimeter set to measure amperage, connect it in series between the negative battery post and the negative battery cable. Ensure all doors are closed, the car is locked (to activate all modules), and wait at least 15-30 minutes for all control modules to 'go to sleep.' A normal draw should be under 50 milliamps (0.05 amps). Anything significantly higher indicates a problem.
  • Isolate the Circuit: Once you've confirmed a draw, start pulling fuses one by one from the fuse box (both under the hood and inside the cabin) while monitoring the multimeter. When the amperage drops significantly, you've found the circuit responsible. This helps narrow down the faulty component.
  • Check Common Culprits: For Genesis vehicles, common sources of parasitic draws can include:
    • Infotainment/Navigation System: A module that fails to power down correctly.
    • Body Control Module (BCM): Can sometimes malfunction and keep various systems active.
    • Door Lock Actuators or Trunk Latch: A faulty switch or motor can draw power.
    • Glove Box or Trunk Light: A light that isn't turning off completely.
    • Aftermarket Accessories: Any non-factory installed electronics (dash cams, alarms, remote starters) are prime suspects.
    • Alternator Diode Failure: While your alternator was tested, a failing diode can sometimes allow current to leak back, causing a draw. This might not always show up on a basic alternator test.

2. OBD Codes & Diagnostics:

While a parasitic draw itself might not always trigger a specific OBD-II code (P-code), a faulty module causing the draw might store a diagnostic trouble code (DTC) within its own system. A professional scan tool can access these module-specific codes (U-codes or B-codes), which can point directly to the problematic component.

3. When to See a Shop:

If you're uncomfortable performing electrical diagnostics or if you've isolated the draw to a complex module (like the BCM or infotainment system), it's best to take your G80 to a qualified Genesis dealership or an independent automotive electrical specialist. They have advanced diagnostic tools and wiring diagrams specific to your vehicle, which can pinpoint the exact cause much more efficiently and prevent further damage.

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