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2018 Charger R/T Battery Drain Mystery - Help!

0

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

Vehicle: 2018 Dodge Charger R/T

Hey everyone,

I'm pulling my hair out over a persistent battery drain issue on my 2018 Dodge Charger R/T. It's got the 5.7L Hemi. The battery keeps dying if the car sits for more than a day or two. I've already replaced the battery once, thinking it was just old, but the problem came right back.

I've done some basic checks. The alternator seems to be charging fine when the car is running, putting out around 14.2-14.4 volts. I also tried a simple parasitic draw test with a multimeter, connecting it in series with the negative terminal, and it shows a draw of about 0.5-0.7 amps after everything should have gone to sleep. This seems high, but I can't pinpoint the source.

I've tried pulling a few fuses related to the radio and interior lights, but the draw doesn't drop significantly. Could it be a module not shutting down properly? Or maybe something with the Uconnect system? Any ideas on what else I should check before I have to take it to the dealership?

✓ Accepted solution

ClearTheCode Admin

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

0

ClearTheCode admin answer:

Persistent battery drains, or parasitic draws, are common and can be incredibly frustrating to diagnose. A draw of 0.5-0.7 amps is definitely too high; a healthy modern vehicle should typically settle down to under 50 milliamps (0.05 amps) after all modules have gone to sleep (which can take 30-60 minutes).

Here's a systematic approach to help you find the culprit:

  1. Wait for Sleep Mode: Ensure you're waiting long enough for all vehicle modules to power down. Lock the doors and wait at least 30-60 minutes after turning off the car before taking your parasitic draw measurement. Opening doors or activating systems will wake modules up.
  2. Fuse Pulling Method: With your multimeter connected and showing the high draw, start systematically pulling fuses one by one from both the under-hood and interior fuse boxes. Watch the multimeter display. When the amperage drops significantly, you've identified the circuit causing the draw. Once the circuit is identified, you can investigate the components on that specific circuit.
  3. Common Culprits in Dodge Vehicles:
    • Uconnect System: Infotainment systems can sometimes fail to power down correctly, especially if there's a software glitch or a faulty component within the head unit.
    • Body Control Module (BCM): The BCM controls many electrical functions and can sometimes stay awake or have an internal fault causing a draw.
    • Aftermarket Accessories: Any non-factory installed items (remote start, stereo upgrades, dash cams) are prime suspects. Disconnect them temporarily to see if the draw disappears.
    • Stuck Relays: A relay that's stuck in the 'on' position can keep a circuit energized. You can often feel or hear a relay click when you pull its fuse.
    • Alternator Diode Failure: While you mentioned good charging voltage, a failing diode in the alternator can sometimes cause a slight parasitic draw. This is less common but worth considering if other avenues fail.

Potential OBD Codes: While a direct code for 'parasitic draw' doesn't exist, if a specific module (like the BCM or Uconnect) is failing to shut down or has an internal fault, it might log a 'U-code' (network communication error) or a 'P-code' related to internal module performance (e.g., P0601, P0606) that a more advanced scanner could retrieve.

When to See a Shop: If you've systematically pulled fuses and cannot isolate the circuit, or if the draw is intermittent, it's time to consult a professional. A qualified automotive technician has specialized diagnostic tools (like thermal cameras for hot spots, advanced scan tools to monitor module sleep states, and current clamps) that can pinpoint the exact component or module causing the issue much more efficiently.

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