Model 3 / Y 12V Battery Replacement
Model 3Model Y
This is the one Tesla repair every owner eventually needs. When the 12V lithium battery dies, the car will sit dead — no touchscreen, no charge port, no locks. The good news: it's a 45-minute job in the driveway, and you don't need Tesla to do it.
When it fails: usually between 3 and 4 years of age, and it can die with almost no warning. If you get the "Schedule service — 12V battery" alert, don't put it off. On newer cars it's a lithium pack up in the frunk area; on older builds it's a traditional lead-acid under the front. These steps cover the lithium replacement on a 2021-2024 Model 3 / Model Y.
Prep: open the frunk while you still can
If the battery is dead, you can't open the frunk from the app or the fob. Use the manual release: pop the front tow-hook cover and pull the wire loop to release the frunk latch.
Remove the frunk trim panels
The frunk carpeted interior sits over a plastic tub. Pull up on the carpet to release the clips, then remove the two 10mm bolts holding the trim in place. Lift the whole assembly out — no tools beyond a socket and a couple of trim clips.
Disconnect the 12V terminal
Before touching the battery, open the charge port door and disconnect the harness so the high-voltage contactors open. Then remove the negative terminal first with the 10mm bolt, then the positive. Tape the positive lead back — you don't want it touching anything while you work.
Remove the battery bracket
The lithium 12V pack sits in a tray held by a bracket across the top. Remove the three T25 Torx screws, then the bracket lifts out. There's a small vent tube on the side — note where it runs before you pull the pack.
Slide the old battery out, drop the new one in
Lift the pack straight up and out of the tray. Reverse to install: new battery in, vent tube reconnected, bracket back on, positive then negative terminals torqued to 5.5 Nm. Reinstall the frunk trim and carpet.
Reset and verify
The car should wake up on its own once the 12V is connected. Open the app and confirm the vehicle responds, then open the doors and touchscreen to verify everything powers up normally. Do a hard reset (hold both scroll wheels for ~10 seconds) if the screen doesn't come on within a couple minutes.
You're done. Recycle the old battery at a parts store — never throw it in household trash.
FAQ
How much does Tesla charge for this? Service center quotes typically run $200-300+ installed. DIY runs about $180 for the part.
Will I lose any settings? No, the 12V replacement preserves your driver profiles; the car doesn't need a reset.