Tesla

I'm opening up my Tesla health monitoring garage

This is a launch post. If you’ve followed the Tesla Longevity Lab channel or seen me reply to threads on Tesla Motors Club and Reddit, you know what I’ve been working on. Today I’m taking the wraps off.

Today, two things go live:

1. t800.io — the website for T800, a long-term health monitoring system for Tesla Model S/X.
2. t800.io/garage — a public daily health report for my own 2017 Model X 100D, updated every morning. It’s the same report any T800 customer will see for their own car. Real CAN telemetry, not a mockup.

That’s the launch. Below is the why.

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.

5 Warning Signs Your Tesla 12V Battery Is Dying

Your Tesla has two batteries. Everyone knows about the big one — the high-voltage pack that gives you 300+ miles of range. But there’s a small 12V lead-acid (or lithium in newer models) battery that powers everything else: the computers, door latches, lights, and the contactors that connect the main pack to the drive system.

When this 12V battery dies, your Tesla becomes a very expensive paperweight. The doors may not open. The screen won’t turn on. And the main battery — fully charged — sits there, useless, because the contactors can’t close without 12V power.

Tesla OBD-II Port: What It Is, Where to Find It, and What You Can Do With It

Every Tesla has an OBD-II port. Most owners don’t know it exists, what it does, or why it matters. Here’s the complete guide.

What Is OBD-II?

OBD-II (On-Board Diagnostics, version 2) is a standardized diagnostic interface required on all vehicles sold in the US since 1996. It provides access to the vehicle’s electronic control systems for emissions testing, diagnostics, and real-time data monitoring.

On traditional gas cars, OBD-II is primarily used for emissions-related data. On Teslas — which have no emissions system — the port provides access to the CAN bus (Controller Area Network), the internal communication backbone that connects every electronic module in the car.

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.