Example · Device troubleshooting

EV range suddenly dropped

Separate the "seasonal and reversible" from the "irreversible decline" first — that decides whether you inflate the tyres, wait for warmer weather, or replace the battery.

现象 · QUESTION

My electric car's range dropped from about 60 km to about 40 km — what is most likely?

已知线索 · CLUES5 条

Measured range fell from roughly 60 km to roughly 40 km
Onset: as autumn began
Pattern: the first part of the charge drains faster, the later part recovers somewhat
Charging: full charge takes slightly less time
Vehicle: about two years old, used for commuting

可能性排序 · HYPOTHESES概率为估计，不是结论

1. Lower usable battery capacity in cold weatherabout 40%

依据：Started with autumn and a 20–30% fall fits low temperature; "fast drain early" is typical of higher internal resistance when cold

2. Under-inflated tyres raising rolling resistanceabout 20%

依据：Falling temperatures reduce tyre pressure too, so this track the same season

3. Battery ageing and capacity fadeabout 20%

依据：Two years old, so it must be weighed alongside temperature; check cycle count and health data

4. A change in the charger or battery-management strategyabout 10%

依据：The shorter full-charge time may relate to this

5. Something else (brake drag, load, a different route)about 10%

依据：Rule out recent changes in riding or driving conditions

怎么验证 · VERIFY

Record temperature against measured range, then retest after a clearly warmer day
Check tyre pressure and reinflate to spec, then retest
Check cycle count or battery health if the app exposes it
Rule out changes in load, route gradient and brake drag

场景还原 · RECONSTRUCT

In cold weather, range recovers automatically once it warms up, and the discharge curve is "fast early, slower later". With ageing, range sits below the original level all year and drifts down month by month, largely independent of temperature.

复盘 · REVIEW

"Wait for a warm day" is a zero-cost discriminator: cold is a reversible seasonal effect, ageing is an irreversible trend. Use it to separate the two before deciding whether to adjust tyres or book a service.

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