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2018 Q50 Battery Drain Mystery - Dying Overnight!

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David L. · rep 0 · May 22, 5:07 AM · 1 replies · solved · Question

Vehicle: 2018 Infiniti Q50 3.0t Luxe

Hey everyone,

I'm pulling my hair out over an issue with my 2018 Infiniti Q50 3.0t Luxe. For the past few weeks, the battery keeps dying overnight. I've had it jump-started multiple times, and even replaced the battery with a brand new one, but the problem persists. It seems like there's a parasitic draw somewhere.

I've checked the obvious things like making sure lights are off and doors are fully closed. Sometimes, the infotainment screen seems to take a while to shut down after I lock the car, but I'm not sure if that's related. Has anyone experienced anything similar with their Q50? What should I be looking for?

It's really frustrating to wake up to a dead car, especially when I have to get to work. Any advice or troubleshooting steps would be greatly appreciated before I take it to the dealership.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 5:07 AM

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ClearTheCode admin answer:

Battery drain, or parasitic draw, is a common and frustrating electrical issue. Here's how to approach diagnosing and resolving it:

  1. Confirm the Draw: First, verify there's an actual draw. With the car off and all accessories off, connect a multimeter in series between the negative battery post and the negative battery cable. A normal draw is typically under 50mA (0.05 amps). Anything significantly higher indicates a problem.
  2. Fuse Pull Test: If a draw is confirmed, start pulling fuses one by one while monitoring the multimeter. When the amperage drops significantly, you've identified the circuit causing the draw. This narrows down the problem area (e.g., infotainment, interior lights, BCM).
  3. Common Culprits:
    • Infotainment System: As you mentioned, a module not shutting down correctly can cause a draw. This is a frequent issue in modern vehicles.
    • Body Control Module (BCM): A faulty BCM can sometimes stay awake or improperly control other modules.
    • Alternator Diode Failure: A failing diode in the alternator can allow current to flow back to the alternator when the car is off, draining the battery. This often presents with a P0562 (System Voltage Low) code.
    • Aftermarket Accessories: Any recently installed aftermarket electronics (stereo, alarm, dash cam) are prime suspects.
    • Stuck Relays: A relay that's stuck in the 'on' position can keep a circuit active.

When to See a Shop: If you're uncomfortable performing electrical tests or can't pinpoint the circuit with the fuse pull test, it's best to take your Q50 to a qualified technician. Diagnosing parasitic draws can be time-consuming and requires specific tools and knowledge. They can perform advanced diagnostics, including thermal imaging to find hot spots indicating active components, and use scan tools to check for modules that aren't entering sleep mode correctly. If you have an OBD-II scanner, check for codes like P0562, which might point to a charging system issue.

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