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2020 RLX Sport Hybrid 12V Battery Draining Overnight

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Mike T. · rep 0 · May 26, 3:40 AM · 1 replies · solved · Question

Vehicle: 2020 Acura RLX Sport Hybrid

Hello fellow Acura owners,

I'm having a persistent issue with my 2020 Acura RLX Sport Hybrid. For the past few weeks, the 12V battery keeps draining overnight. I'll get in the car in the morning, and it's completely dead – no lights, no ignition, nothing. I can jump-start it, and it runs fine all day, but if it sits for more than 8-10 hours, it's dead again.

I had the 12V battery tested at AutoZone, and they said it's good. I've tried to make sure everything is off when I leave the car, but the problem persists. Could this be a parasitic draw, and if so, what are common culprits on the RLX Sport Hybrid? It's really frustrating to deal with this every few days.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 26, 3:40 AM

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ClearTheCode admin answer:

A recurring 12V battery drain in your 2020 Acura RLX Sport Hybrid, especially after the battery tests good, strongly suggests a parasitic draw. This means something is continuously drawing power even when the car is off. Here's how to approach it:

  1. Confirm the 12V Battery Health: While AutoZone tested it, sometimes a battery can show good voltage but lack the necessary cold cranking amps (CCA). A professional load test by an Acura dealer or a reputable shop would be more thorough.
  2. Check for Obvious Culprits:
    • Interior Lights: Ensure all dome lights, glove box lights, and trunk lights are turning off completely.
    • Aftermarket Accessories: Any recently installed dash cams, audio systems, or tracking devices could be drawing power.
    • USB Chargers: Make sure nothing is left plugged into USB ports.
  3. Perform a Parasitic Draw Test: This requires a multimeter and some patience:
    • Connect the multimeter in series between the negative battery terminal and the negative battery cable (after ensuring the car is off and all doors are closed/latched).
    • Wait for the car's modules to 'go to sleep' (this can take 20-45 minutes). The draw should drop to a very low level (typically under 50mA for modern vehicles).
    • If the draw is high, start pulling fuses one by one, observing the multimeter. When the draw significantly drops, you've found the circuit responsible.
  4. Common RLX Sport Hybrid Specific Issues:
    • Hands-Free Link (Bluetooth) Module: These modules are known across various Acura/Honda models to sometimes stay active and draw power.
    • Infotainment System/Navigation Unit: A faulty or stuck infotainment module can prevent the car from fully shutting down.
    • Keyless Access System: Issues with the smart key system or door handle sensors can keep modules awake.
    • Hybrid System Components: While less common for the 12V, a fault in a hybrid system module could potentially cause an indirect draw or prevent proper charging of the 12V.

When to see a shop:

  • If you're uncomfortable performing a parasitic draw test yourself.
  • If you identify a circuit with a high draw but can't pinpoint the exact component (e.g., the 'Audio' fuse causes a drop, but you don't know if it's the head unit or an amplifier).
  • If the issue persists after checking common items. A dealership has specialized diagnostic tools to communicate with all modules and pinpoint which one is staying active.
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