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Battery Drain Overnight - 2020 Regal Sportback

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Chris P. · rep 0 · May 22, 3:49 AM · 1 replies · solved · Question

Vehicle: 2020 Buick Regal Sportback Essence

My 2020 Buick Regal Sportback Essence keeps having its battery die overnight. I've replaced the battery once already, and it tested fine. I'm careful to turn off all lights and accessories, and I don't leave anything plugged into the ports.

It's incredibly frustrating to wake up to a dead car. Is there a common parasitic draw issue with these models? What's the best way to diagnose where the power is going when the car is off? No warning lights are on when it's running.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 3:49 AM

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ClearTheCode admin answer: An overnight battery drain on your 2020 Buick Regal Sportback, especially after a battery replacement, strongly suggests a parasitic draw. This means something in the vehicle is consuming power even when the car is off and locked.

Here's how to approach diagnosing a parasitic draw and common culprits:

  1. Measure the Draw:
    • Connect a multimeter in series between the negative battery post and the negative battery cable. Set the multimeter to measure amperage (A or mA).
    • Ensure all doors are closed, lights are off, and the car has been asleep for at least 30 minutes (some modules stay active for a while after shutdown). A normal draw is usually under 50 mA (0.05A).
  2. Pull Fuses One by One:
    • With the multimeter still connected and showing the draw, start pulling fuses from the fuse box (both under the hood and inside the cabin) one at a time.
    • Watch the multimeter. When the amperage drops significantly, you've found the circuit responsible for the draw.
    • Once you identify the circuit, you can then investigate the components on that circuit.

Common Culprits for Parasitic Draws:

  • Infotainment/Radio System: A module that isn't shutting down properly.
  • Body Control Module (BCM): The BCM controls many electrical functions and can sometimes stay awake.
  • Aftermarket Accessories: Anything added to the car (remote start, alarm, dash cam, stereo) can be a source if wired incorrectly.
  • Glove Box/Trunk Lights: Sometimes these lights stay on due to a faulty switch.
  • Faulty Relays: A relay that is stuck in the 'on' position can continuously power a circuit.
  • OnStar/Telematics Module: These systems are always connected and can sometimes malfunction.

When to see a shop:

  • If you're uncomfortable working with electrical systems or don't have a multimeter.
  • If you've pulled all accessible fuses and can't find the source of the draw.
  • If the draw is coming from a complex module like the BCM or infotainment system, which may require specialized diagnostic tools to pinpoint the exact component or software issue. A professional can quickly identify and rectify the problem, saving you time and frustration.
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