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2016 Model S 75D - 'Replace 12V Battery Soon' Warning

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Tom H. · rep 0 · May 22, 5:21 AM · 1 replies · solved · Question

Vehicle: 2016 Tesla Model S 75D

Hi all,

I've been getting a persistent 'Replace 12V Battery Soon' warning on my 2016 Tesla Model S 75D for the past few weeks. It started intermittently, but now it's almost always there when I get in the car. I haven't noticed any major issues yet, but sometimes the screen takes a bit longer to boot up, and I'm worried about being stranded.

I know the 12V battery is separate from the main high-voltage battery, but I'm not sure how critical this warning is or if it's something I can replace myself. Is this a common problem for older Model S vehicles? What are the risks if I don't address it quickly?

Any insights or experiences with this warning would be helpful. Thanks!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 5:21 AM

0

ClearTheCode admin answer:

The 'Replace 12V Battery Soon' warning in your 2016 Tesla Model S 75D is a very common and critical alert that should not be ignored. While the main high-voltage battery powers the drivetrain, the 12V auxiliary battery powers all the vehicle's low-voltage systems, including the infotainment screen, door locks, lights, and even the contactors that connect the high-voltage battery.

Potential Causes:

  • Aging 12V Battery: Like any lead-acid battery, the 12V battery has a finite lifespan, typically 3-5 years. Your 2016 Model S is well within the age range where this battery would need replacement.
  • Charging System Issue: Less common, but a fault in the DC-DC converter (which charges the 12V battery from the high-voltage battery) could lead to undercharging and premature battery wear.
  • Parasitic Drain: A component drawing excessive power when the car is off could prematurely drain the 12V battery.

When to See a Shop:

You should schedule service with Tesla as soon as possible. While you might not be experiencing major issues yet, a failing 12V battery can lead to a complete loss of power for critical systems, rendering the car inoperable. This includes being unable to open doors, start the car, or even engage the high-voltage system. It's not a matter of if it will fail, but when.

What to Expect at the Shop:

  1. Battery Health Check: Technicians will test the current state of health and charge of your 12V battery.
  2. Replacement: If the battery is confirmed to be weak, they will replace it with a new one. Tesla uses specific AGM (Absorbent Glass Mat) batteries designed for their vehicles.
  3. System Check: After replacement, they will ensure all low-voltage systems are functioning correctly and that the DC-DC converter is properly charging the new battery.

While some experienced DIYers might attempt 12V battery replacement, it's generally recommended to have Tesla service perform it due to the vehicle's complex electronics and the need for proper battery type and installation.

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