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2018 Discovery HSE Battery Draining Fast - Electrical Gremlins?

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Laura J. · rep 0 · May 22, 6:32 AM · 1 replies · solved · Question

Vehicle: 2018 Land Rover Discovery HSE

Hey everyone,

I'm having a really frustrating issue with my 2018 Land Rover Discovery HSE. It seems like if I leave it parked for more than two days, the battery is completely dead. I've had to jump-start it multiple times now, and it's getting old.

I recently replaced the battery, thinking that was the problem, but the new one is doing the exact same thing. Sometimes, before it dies, I notice the infotainment screen takes longer to boot up, or the parking sensors act a bit weird. Could this be a parasitic draw?

I'm worried about taking it to the dealership without some idea of what's going on. Has anyone else experienced something similar with their Discovery or other Land Rover models from this era? Any tips on what to check first?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 6:32 AM

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ClearTheCode admin answer:

A recurring battery drain, even after replacing the battery, strongly suggests a parasitic draw. This means one or more electrical components are not shutting down properly when the vehicle is off, continuously drawing power. This is a common issue in modern vehicles with complex electrical systems, including Land Rovers.

Here's what could be causing it and what to do:

  1. Identify the Source (DIY Check):

    • Multimeter Test: A parasitic draw test involves connecting a multimeter in series with the negative battery terminal and observing the amperage draw. A healthy draw should typically be below 50mA (0.05A) after all modules have gone to sleep (which can take up to 30-60 minutes after locking the car).
    • Fuse Pulling: If the draw is high, systematically pull fuses one by one while monitoring the multimeter. When the draw drops significantly, you've identified the circuit responsible. This can narrow down the faulty component (e.g., infotainment module, door lock module, climate control unit).

  2. Common Causes for Land Rover Models (2016-2026):

    • Infotainment System: The InControl Touch Pro system or related modules can sometimes fail to enter sleep mode, leading to a constant draw. Software glitches or faulty hardware are possible.
    • Telematics Control Unit (TCU): Modules like the TCU (for emergency calls, tracking, etc.) can sometimes stay active.
    • Door Lock/Window Modules: A faulty switch or module in a door can prevent the system from fully shutting down.
    • Alternator Diode Failure: Less common for a parasitic draw, but a failing alternator diode can cause a slow drain by allowing current to flow back through the alternator when the engine is off. This often presents with a P0562 (System Voltage Low) code.
    • Aftermarket Accessories: Any recently installed aftermarket electronics (dash cams, alarms, sound systems) that aren't wired correctly can cause a drain.

  3. When to See a Shop:

    • If you're uncomfortable performing electrical tests or can't pinpoint the source with the fuse-pulling method.
    • If the draw is intermittent or difficult to diagnose.
    • If the issue points to a complex module (like the infotainment or TCU) that requires specialized diagnostic tools for software updates or replacement.
    • If you're getting persistent diagnostic trouble codes (DTCs) like P0562 (System Voltage Low) or U-codes indicating module communication errors, which can be symptoms of a deeper electrical problem.

A qualified Land Rover specialist or dealership will have the specific diagnostic equipment (like SDD or Topix JLR) to communicate with all modules, check their sleep status, and identify the exact source of the parasitic drain more efficiently.

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