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2018 Charger R/T - Persistent Battery Drain Issue

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Robert C. · rep 0 · May 22, 5:45 AM · 1 replies · solved · Question

Vehicle: 2018 Dodge Charger R/T

Hey everyone,

I'm having a really frustrating issue with my 2018 Dodge Charger R/T. If I leave it parked for more than two days, the battery is completely dead. I've already replaced the battery once, and the new one tests fine. The alternator also checks out, so it seems like it's charging properly when the car is running.

It feels like something is constantly drawing power even when the car is off. I've checked the obvious things like making sure lights are off and doors are fully closed. Has anyone else experienced a parasitic drain on their 2018 Charger, or any other Dodge model from this generation? Any tips on where to start looking would be greatly appreciated.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 5:45 AM

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ClearTheCode admin answer:

A persistent battery drain, or parasitic draw, is a common and frustrating electrical issue. It means something is drawing power even when the vehicle is off. Here's how to approach diagnosing it:

  1. Confirm the Draw:

    • Charge your battery fully. Disconnect the negative battery terminal. Connect a multimeter in series between the negative battery post and the disconnected negative battery cable. Set the multimeter to measure amps (A). A normal draw should be around 20-50 milliamps (mA) after the vehicle has 'gone to sleep' (which can take 15-30 minutes after closing doors and locking).

  2. Isolate the Circuit:

    • Once you've confirmed a high draw, start pulling fuses one by one from the fuse box (both under the hood and inside the cabin), while watching the multimeter. When the amperage drops significantly, you've found the circuit responsible for the draw.

  3. Common Culprits for Dodge Chargers (2016-2026):

    • Uconnect Module: These systems can sometimes fail to power down correctly, keeping the module awake.
    • Aftermarket Accessories: Any non-factory installed alarms, stereos, or remote starters are frequent sources of parasitic draws.
    • Glove Box/Trunk Lights: Ensure these lights are turning off when closed. A faulty switch can keep them on.
    • Door Ajar Switches: A faulty switch can trick the car into thinking a door is open, keeping modules awake.
    • Body Control Module (BCM): A failing BCM can sometimes cause various electrical components to stay active.

  4. Check for Diagnostic Trouble Codes (DTCs):

    • Even if your check engine light isn't on, a module that isn't shutting down might log a 'wake-up' code or a communication error. Use an OBD-II scanner to check all modules for stored or pending codes. Codes like U0100 (Lost Communication with ECM/PCM) or U0140 (Lost Communication with BCM) could indicate a module staying awake or failing.

When to See a Shop: If you're uncomfortable working with electrical systems, or if you've pulled all fuses and still can't find the source of the draw, it's best to take your Charger to a qualified automotive electrical specialist. They have advanced diagnostic tools and experience to pinpoint complex electrical issues, especially those involving integrated modules.

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