Battery

How to Check Your Tesla Battery Health in 2026

Your Tesla’s battery pack is the single most expensive component in the vehicle — worth $12,000 to $22,000 to replace. Yet Tesla gives owners surprisingly little visibility into its long-term health.

Here’s what you actually need to know.

What Tesla Shows You (And What It Doesn’t)

The built-in Tesla UI displays your current State of Charge (SOC) and estimated range. That’s it. There’s no:

• Cell-level voltage data
• Temperature spread between cells
• Degradation trend over time
• Isolation resistance readings
• Charge cycle count

These are the metrics that actually predict battery longevity — and Tesla keeps them locked behind the CAN bus.

Tesla Phantom Drain: Causes, Diagnosis, and How to Fix It

You wake up, check your Tesla app, and your car lost 8 miles of range overnight. It was parked in your garage, plugged in to nothing, doing… what exactly?

This is phantom drain — and it’s one of the most common Tesla owner complaints. Here’s what’s actually happening and what you can do about it.

What Is Phantom Drain?

Phantom drain (also called vampire drain) is the gradual loss of battery charge when your Tesla is parked and not in use. Every Tesla experiences some level of it — the car’s computers never fully shut down. But “normal” is 1–3 miles per day. Anything beyond that deserves investigation.

What's Normal Tesla Battery Degradation? Data from 100,000+ Vehicles

“My Tesla lost 15 miles of range in the first year — is that normal?”

This is probably the most common question in Tesla forums. The short answer: yes, probably. But let’s look at the data.

The Degradation Curve

Tesla batteries don’t degrade linearly. The pattern looks like this:

1. Year 1 (0–15,000 miles): 3–5% capacity loss. This is the steepest decline and it’s completely normal. The battery chemistry stabilizes during initial cycling.