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2018 Outback Battery Draining Fast & Charging System Warning Light

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Mike T. · rep 0 · May 25, 2:16 AM · 1 replies · solved · Question

Vehicle: 2018 Subaru Outback 2.5i Premium

Hey everyone, I'm having a persistent issue with my 2018 Subaru Outback 2.5i Premium. For the past few weeks, the battery seems to be draining overnight, and I've had to jump-start it a few times. The battery light has also flickered on and off while driving.

I replaced the battery about 6 months ago, thinking that was the problem, but the issue has returned. Could it be the alternator or something else electrical? I'm worried about getting stranded, especially with winter coming up. Any ideas on what I should check first?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 2:16 AM

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ClearTheCode admin answer:

This sounds like a classic charging system issue, which can be frustrating. Here's a breakdown of potential causes and steps to diagnose:

Causes:

  • Failing Alternator: The most common culprit for a battery light and draining issues, as it's responsible for charging the battery while the engine runs.
  • Parasitic Draw: Something in the vehicle is staying on and drawing power even when the car is off.
  • Loose or Corroded Battery Terminals: Poor connections can prevent proper charging or power delivery.
  • Faulty Voltage Regulator: Often integrated into the alternator, it ensures consistent voltage to the battery.

Diagnostic Steps:

  1. Inspect Battery Terminals: Ensure they are clean, tight, and free of corrosion. A poor connection can mimic a dead battery.
  2. Test Battery Voltage: With the car off, a healthy battery should read around 12.6 volts. After starting, it should be 13.5-14.5 volts, indicating the alternator is charging.
  3. Test Alternator Output: Many auto parts stores offer free battery and alternator testing. This is crucial for confirming if the alternator is failing.
  4. Check for Parasitic Draw: This is more involved. It requires a multimeter to measure current draw with the car off. You'd typically pull fuses one by one to isolate the circuit causing the drain.

Common OBD Codes:

  • P0562: System Voltage Low
  • P0560: System Voltage Malfunction

When to See a Shop: If your battery and alternator tests are inconclusive, or if you're uncomfortable performing the parasitic draw test, it's best to see a professional. Persistent battery draining can be a sign of a deeper electrical issue that requires specialized tools to diagnose accurately. A shop can pinpoint the exact cause and prevent further damage or inconvenience.

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