why does my Tesla Model S Original (2012-2020) battery die overnight when parked

Tesla Model S Plaid/Refresh (2021-present)

Error Codes

1-3 hours

Time

medium

Difficulty

high

Severity

3 min read

536 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

1-3 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the high voltage battery before working on the electrical system to avoid shock
•Allow the vehicle to cool before performing any maintenance

Symptoms

•Battery percentage drops significantly overnight
•"Battery not charging" warning displayed when attempting to start
•Reduced range indicated on the dashboard
•Frequent notifications regarding low battery state
•Inability to use remote features via the Tesla app

Diagnostic Steps

1
Scan the vehicle using the Tesla service tool to check for any error codes related to the battery or charging system
2
Inspect the 12V battery voltage; it should be above 12.5 volts
3
Check for any parasitic drain by measuring the current draw from the battery when the vehicle is in a sleep mode
4
Investigate the status of the vehicle's software version and update if necessary, as software bugs can affect battery management
5
Review vehicle settings to ensure features like Sentry Mode or Cabin Overheat Protection are not unnecessarily active

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

•Socket set
•Multimeter
•Basic hand tools
•Tesla service tool

Parts Required

•New 12V battery

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Diagnostic Steps

1
Scan the vehicle using the Tesla service tool to check for any error codes related to the battery or charging system
2
Inspect the 12V battery voltage; it should be above 12.5 volts
3
Check for any parasitic drain by measuring the current draw from the battery when the vehicle is in a sleep mode
4
Investigate the status of the vehicle's software version and update if necessary, as software bugs can affect battery management
5
Review vehicle settings to ensure features like Sentry Mode or Cabin Overheat Protection are not unnecessarily active

Solution

1. Preparation

Gather necessary tools and parts.
Ensure the vehicle is parked in a safe location.
Disconnect the vehicle from any charging source.

2. Check and Replace the 12V Battery

Tools Required: Socket set, multimeter, basic hand tools.
Sub-steps:
1. Open the front trunk (frunk) and locate the 12V battery.
2. Use a multimeter to check the voltage of the 12V battery; if below 12.5 volts, consider replacement.
3. Disconnect the negative terminal first followed by the positive terminal.
4. Remove the mounting bracket and lift out the old battery.
5. Install the new 12V battery in reverse order (positive first, then negative).
6. Secure the battery with the mounting bracket.

3. Inspect Vehicle Settings

Tools Required: Tesla mobile app or onboard touchscreen.
Sub-steps:
1. Navigate to 'Settings' on the touchscreen.
2. Disable features like Sentry Mode and Cabin Overheat Protection if unnecessary.
3. Confirm all software updates are applied.

4. Address Parasitic Drain

Tools Required: Multimeter, fuse puller.
Sub-steps:
1. With the vehicle asleep, disconnect the negative terminal of the 12V battery again.
2. Connect the multimeter in series with the negative terminal and the battery to measure current draw.
3. Pull fuses one at a time to identify the circuit causing excessive current draw.
4. Repair or replace faulty components indicated by the excessive current draw.