why does my Tesla Model S Original (2012-2020) battery die when the car is off

Tesla Model S Plaid/Refresh (2021-present)

Error Codes

1-2 hours

Time

medium

Difficulty

high

Severity

3 min read

543 words

⚠️ Safety Warning

This issue requires immediate attention. If you are not experienced with automotive repairs, consult a professional mechanic. Working on critical systems can be dangerous.

Problem Statement

Learn how to diagnose and fix battery drain issues in Tesla Model S (2012-2020). Step-by-step guide with symptoms, diagnostic steps, and repair instructions.

Affected Component

Electrical

Estimated Time

1-2 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the negative battery terminal before working on electrical systems to avoid short circuits.
•Allow the vehicle to cool before attempting any repairs.

Symptoms

•Battery drains significantly while the vehicle is parked.
•Vehicle takes longer to start or fails to start due to low battery.
•"Battery Low" warning displayed on the dashboard.
•Inability to access features such as remote unlocking or climate control.
•Increased frequency of charging required.

Diagnostic Steps

1
Check the battery voltage using a multimeter to determine the state of charge.
2
Use the Tesla app to review historical battery usage and see if any systems are using excessive power.
3
Inspect for any aftermarket devices or accessories that may draw power when the vehicle is off.
4
Examine the vehicle's logs for any active processes or systems that remain on while parked.
5
Test the 12V battery for proper voltage and health, as it can influence parasitic drain.
6
Conduct a parasitic draw test using an ammeter to measure current draw while the vehicle is off.

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

✓Test the affected component to ensure it functions correctly
✓Check for any error codes or warning lights
✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

•Follow the manufacturer's recommended maintenance schedule
•Address warning signs early before they develop into major issues
•Use quality parts and fluids recommended for your vehicle
•Keep detailed records of all repairs and maintenance

Tools & Equipment Required

•Multimeter
•Ammeter
•Socket set
•Screwdriver set

Parts Required

•12V battery (if replacement is necessary)

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Symptoms

•Battery drains significantly while the vehicle is parked.

•Vehicle takes longer to start or fails to start due to low battery.

•"Battery Low" warning displayed on the dashboard.

•Inability to access features such as remote unlocking or climate control.

•Increased frequency of charging required.

Diagnostic Steps

1
Check the battery voltage using a multimeter to determine the state of charge.
2
Use the Tesla app to review historical battery usage and see if any systems are using excessive power.
3
Inspect for any aftermarket devices or accessories that may draw power when the vehicle is off.
4
Examine the vehicle's logs for any active processes or systems that remain on while parked.
5
Test the 12V battery for proper voltage and health, as it can influence parasitic drain.
6
Conduct a parasitic draw test using an ammeter to measure current draw while the vehicle is off.

Solution

1. Preparation

Gather tools, including a multimeter, ammeter, and basic hand tools.
Ensure the vehicle is safely parked and turned off.
Disconnect the negative terminal of the 12V battery to prevent short circuits.

2. Inspect and Replace 12V Battery

Check Battery Condition:
- Use a multimeter to test the voltage of the 12V battery. If it reads below 12.4 volts, it may need replacement.
Remove the 12V Battery:
- Disconnect the negative terminal first, then the positive terminal.
- Remove the battery hold-down bracket using a socket set.
- Carefully lift out the 12V battery.
Install New Battery:
- Place the new battery in the compartment.
- Secure it with the hold-down bracket and reconnect the positive terminal first, followed by the negative terminal.

3. Reset Vehicle Systems

Reconnect the main battery if it was disconnected.
Power on the vehicle and perform a soft reset by holding down the steering wheel buttons until the screen reboots.
Allow the vehicle to recalibrate and check for any error messages.

4. Check for Software Updates

Use the touchscreen to navigate to "Software" and check for any available updates.
Install updates if necessary to optimize battery management systems.