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2018 Model S 75D - Noticeable Range Drop & Slower Supercharging

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Sarah K. · rep 0 · May 25, 4:00 AM · 1 replies · solved · Question

Vehicle: 2018 Tesla Model S 75D

My 2018 Tesla Model S 75D has been experiencing a noticeable drop in its maximum range lately. I used to get around 230-240 miles on a full charge, but now it's closer to 200-210 miles, sometimes even less. It feels like the degradation has accelerated over the past few months.

On top of that, supercharging seems slower than it used to be. It takes longer to reach a decent charge level, and the peak charging rates I see are lower. I've tried different Supercharger locations, and it's consistent across them.

Is this normal battery degradation for a 2018 model, or could something else be going on with the battery management system (BMS) or the battery itself? I keep it charged between 20-80% mostly and rarely go to 100% unless for a trip. Any thoughts or similar experiences?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 4:00 AM

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ClearTheCode admin answer:

  1. Initial Assessment: A significant drop in estimated range and slower Supercharging rates on a 2018 Tesla Model S 75D could indicate normal battery degradation over time, but it could also point to an issue with the battery pack or its management system (BMS). Given the age, some degradation is expected, but an accelerated or sudden drop warrants investigation.

  2. Common Causes:

    • Battery Degradation: All lithium-ion batteries degrade over time and cycles. Factors like age, number of charge cycles, exposure to extreme temperatures, and frequent deep discharges/charges can accelerate this.
    • Battery Management System (BMS) Imbalance: The BMS monitors individual cells within the battery pack. If cells become imbalanced, the BMS might limit the overall capacity or charging speed to protect the pack, even if the total energy available is higher.
    • Contactor Issues: The main battery contactors can degrade over time, leading to increased resistance and affecting both charging and discharge efficiency.
    • Software Glitch: Less common, but sometimes a software issue can misreport range or limit charging. A hard reboot might temporarily resolve this.

  3. DIY Checks:

    • Battery Calibration: Try charging your vehicle to 100% and driving it down to a very low percentage (e.g., 10-15%) before recharging to 100% again. Do this a few times. This can sometimes help the BMS recalibrate and provide a more accurate range estimate.
    • Hard Reboot: Perform a two-button scroll wheel reboot (hold both scroll wheels down until the screen goes black and the Tesla 'T' appears) to rule out minor software glitches.
    • Check Charging History: Review your vehicle's charging history (if available in your app or settings) to see if you can identify a pattern or specific event that coincided with the change.

  4. When to See a Shop:

    • Soon: If the range drop is significant and persistent, or if the Supercharging speeds remain consistently low after attempting calibration, it's crucial to schedule a service appointment with Tesla. They have specialized diagnostic tools to assess the health of your battery pack and BMS.
    • Warranty Check: Your 2018 Model S 75D likely has an 8-year/120,000-mile battery and drive unit warranty. If your degradation falls below a certain threshold (e.g., 70% retention), it might be covered under warranty. Tesla can provide a definitive battery health report.

  5. Diagnostics at a Service Center: Tesla technicians will:

    • Run advanced diagnostics on the battery pack and BMS to check for cell imbalances, contactor resistance, or other internal faults.
    • Evaluate the battery's state of health (SOH) and compare it against expected degradation curves.
    • Check for specific Tesla error codes related to battery performance, such as BMS_a062 (internal battery fault) or BMS_w026 (charging power limited).
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