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2018 Sorento EX - Persistent Battery Drain Issue, Driving Me Nuts!

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Mike T. · rep 0 · May 25, 2:10 AM · 1 replies · solved · Question

Vehicle: 2018 Kia Sorento EX

Hey everyone,

I'm having a really frustrating issue with my 2018 Kia Sorento EX. For the past few weeks, the battery keeps dying overnight or after sitting for a day. I've replaced the battery twice, and had the alternator checked, both are fine. It seems like something is constantly drawing power, even when the car is off.

I've tried checking for obvious culprits like lights left on, but no luck. Has anyone experienced a parasitic draw on their Sorento? What did you find was the cause? I'm getting tired of jump-starting it every other morning. Any advice or common problem areas would be greatly appreciated before I take it to the dealer.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 2:10 AM

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ClearTheCode admin answer:

A persistent battery drain, or parasitic draw, is a common but often tricky electrical problem. It means a component is drawing power even when the vehicle is off. For your 2018 Kia Sorento EX, several modules or systems could be at fault.

Common Causes:

  1. Faulty Infotainment System/Head Unit: These systems can sometimes fail to power down completely, staying in a 'sleep' mode that draws significant current.
  2. Body Control Module (BCM) Issues: The BCM controls many vehicle functions and can sometimes fail to enter sleep mode or incorrectly activate other components.
  3. Aftermarket Accessories: Any non-factory installed electronics (dash cams, remote starters, audio upgrades) can be a source of draw if not wired correctly.
  4. Stuck Relays: A relay that remains 'on' can keep a circuit active, draining the battery.
  5. Faulty Door/Hood Switches: If the car thinks a door or the hood is ajar, it might keep interior lights on or security systems active.
  6. Alternator Diode Leak: While you mentioned the alternator was checked, a subtle diode leak can sometimes be missed and cause a slow drain.

Diagnostics & When to See a Shop:

  1. Perform a Parasitic Draw Test: This involves connecting a multimeter in series with the negative battery cable and observing the current draw after the vehicle has been fully shut down (usually 30-60 minutes for all modules to 'sleep'). A normal draw is typically under 50mA.
  2. Fuse Pull Method: Once you confirm a draw, systematically pull fuses one by one while monitoring the multimeter. When the current drops significantly, you've identified the circuit causing the draw.
  3. Check for OBD Codes: Even without a check engine light, some modules might store U-codes (network communication issues) or B-codes (body electrical issues) that could point to a culprit.

Given that you've already replaced the battery and checked the alternator, a professional diagnosis is recommended. A qualified technician can perform a comprehensive parasitic draw test, use a scan tool to check for module activity, and pinpoint the exact component or circuit at fault. This can save you a lot of time and prevent further battery replacements.

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