Tesla

Why a Good Tesla Monitor Should Almost Never Alert You

Here is the uncomfortable truth about any health monitor: it is only worth the one alert you actually believe.

The first time your car monitor cries wolf, you forgive it. The second time, you start to doubt it. By the third, you’ve muted the notifications — and now the expensive failure it was built to catch sails through to a dead car in a parking garage. A monitor you’ve learned to ignore isn’t a safety feature. It’s a widget.

5 Warning Signs Your Tesla 12V Battery Is Dying

Your Tesla has two batteries. Everyone knows the big one — the high-voltage pack behind your range. Almost nobody thinks about the small 12V battery that powers everything else: the computers, the door latches, the lights, and the contactors that connect the main pack to the drive system.

When the 12V dies, your Tesla becomes an 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. It strands more Teslas than the big pack ever will, and Tesla shows you none of its health.

My Model X Went In for FSD Repair. The Loaner Was a HW4 Model Y.

FSD v12.6.4 on HW3 vs FSD v14.2.2.5 on HW4, tested on real Vancouver roads.

I didn’t plan this comparison. The service appointment did.

My 2017 Model X 100D (HW3, with a paid MCU2 + HW3 retrofit done years ago) went into Tesla’s Vancouver service center for an intermittent Autopilot dropout — diagnosis: overheating in the self-driving control unit. Tesla replaced the Autopilot ECU (2nd and 3rd gen modules) under warranty. The loaner they handed me was a 2026 Model Y on HW4, and I had it for one day.

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. 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.

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 figures in this article are drawn from published large-fleet degradation datasets — chiefly Geotab’s EV battery degradation study, Recurrent’s Tesla range reports, and Tesla’s own Impact Report — cross-referenced with owner-reported numbers on Tesla Motors Club and Reddit. They’re population averages: your individual pack depends on climate, charging habits, and configuration.