Troubleshooting

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.

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.