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2018 Sorento EX - Persistent Battery Drain Mystery

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Chris P. · rep 0 · May 22, 3:09 AM · 1 replies · solved · Question

Vehicle: 2018 Kia Sorento EX

Hey everyone, I'm pulling my hair out over a persistent battery drain issue on my 2018 Kia Sorento EX. If I let it sit for more than 24-36 hours, the battery is completely dead. I've replaced the battery twice, and had the alternator tested, which came back good.

I've tried disconnecting accessories, but it's hard to pinpoint. Could it be a faulty module staying awake, or maybe something with the infotainment system? I'm not getting any warning lights on the dash, which makes it even more frustrating. Any ideas on where to start looking for a parasitic draw?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 3:09 AM

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ClearTheCode admin answer:

Persistent battery drain, also known as a parasitic draw, is a common and frustrating electrical issue. Here's a systematic approach to diagnose and resolve it:

  1. Perform a Parasitic Draw Test:

    • Ensure all doors are closed, lights are off, and the vehicle is 'asleep' (this can take 15-30 minutes after locking).
    • Disconnect the negative battery terminal.
    • Connect a multimeter in series between the negative battery post and the negative battery cable (set to Amps).
    • A normal draw should be around 20-50 milliamps (mA). Anything significantly higher indicates a problem.

  2. Isolate the Circuit:

    • Once you've confirmed a high draw, start pulling fuses one by one while monitoring the multimeter. When the amperage drops significantly, you've found the problematic circuit.
    • Common culprits include the radio/infotainment system, interior lights, power seats, alarm system, or a faulty body control module (BCM).

  3. Check for Specific Components:

    • Infotainment System: A software glitch or a module that fails to power down can cause a draw. Check for any recent updates or aftermarket installations.
    • Alternator Diode: Although your alternator tested good, a failing diode can cause a small draw. This is less common but worth considering if other tests fail.
    • Door/Trunk Switches: A faulty switch might keep a light or module active, thinking a door is ajar.
    • Aftermarket Accessories: Any non-factory installed items (dash cams, remote starters, sound systems) are prime suspects.

When to See a Shop: If you're uncomfortable performing electrical tests or can't pinpoint the source after trying the above steps, it's best to take your Sorento to a qualified automotive electrician or a Kia dealership. They have specialized diagnostic tools and experience to trace complex electrical issues, especially those involving vehicle modules and wiring harnesses. Ignoring a parasitic draw can lead to premature battery failure and potential damage to other electrical components.

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