Tesla Battery Health Check: How to Measure Degradation (and What's Normal)

How to measure your Tesla's battery health

Note the original rated range for your exact model and year (window sticker or Tesla's spec page at the time).
Read the car's estimated range at 100%. Either charge to 100% occasionally (fine before a trip), or divide the displayed range by the state of charge: range at 100% ≈ shown range ÷ (battery % ÷ 100). For example, 253 mi at 78% ≈ 324 mi.
Degradation ≈ 1 − (range at 100% ÷ original range). Example: 1 − 324 ÷ 333 ≈ 2.7%.
Repeat monthly. Single readings jump around with temperature and the battery management system's estimate; the trend is what counts.

Full-charge range estimate

One car, 18 months, after delivery

Example data

What's normal?

Lithium-ion packs lose a little capacity early and then level off. Tesla's own impact reporting has said Model S and Model X packs retain roughly 88% of capacity on average after 200,000 miles. Expect a few percent in the first year or two, slower after that. A sudden drop is more often a range-estimate calibration issue than real capacity loss, so look at weeks of data before worrying.

Tesla battery warranty thresholds

Model	Battery & drive unit warranty
Model 3 / Model Y (RWD)	8 years or 100,000 mi, 70% retention
Model 3 / Model Y (Long Range, Performance)	8 years or 120,000 mi, 70% retention
Model S / Model X / Cybertruck	8 years or 150,000 mi, 70% retention

Terms vary by region and build date; confirm in your vehicle's warranty document on tesla.com.

Habits that help

Daily charge limit at Tesla's recommended setting for your pack (many cars default to 80–90%; LFP-battery cars recommend charging to 100% at least weekly).
Avoid leaving the car at very high or very low charge for long periods.
Supercharging is fine; frequent DC fast charging in heat may add some wear.

Check battery health with AI

With AskMyEV, ask “How's my battery holding up?” Your AI reads your car's current state and, on paid plans, its history log (snapshots of battery level and rated range taken only when the car is already awake) to compute the trend for you. The free one-time health check reports battery, tires, charging and active alerts with no card.

Claude · AskMyEV connectorExample

How has my range at 100% changed since spring?

Claudeused AskMyEV

Since April your estimated full-charge range went from 325 mi to 324 mi, essentially flat. Over 18 months it's down about 2.7% from 333 mi, which is normal for this age.

Frequently asked questions

How do I check my Tesla battery health?

Divide the displayed range by the battery percentage to estimate range at 100%, compare it with the original rated range, and track it monthly. Tools like AskMyEV can do this automatically and explain the trend.

How much degradation is normal for a Tesla?

A few percent in the first year or two is typical, then it slows. Tesla has reported average retention around 88% after 200,000 miles for Model S and X.

When does Tesla replace a battery under warranty?

If capacity falls below 70% within the warranty period (8 years and 100,000–150,000 miles depending on model).

Does the AskMyEV health check cost anything?

No. The one-time health check is free and needs no card. It's limited to one per car every 90 days.