my Tesla Model S Original (2012-2020) battery dies overnight when parked, why?

Tesla Model S Plaid/Refresh (2021-present)

Error Codes

2-3 hours

Time

medium

Difficulty

high

Severity

3 min read

560 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 solutions.

Affected Component

Electrical

Estimated Time

2-3 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical systems.
•Allow the vehicle to cool before accessing battery components.

Symptoms

•Battery discharges completely overnight
•Vehicle fails to start in the morning
•Low Battery warning displayed on the dashboard
•Increased frequency of charging required
•Possible software updates pending notification

Diagnostic Steps

1
Check the battery voltage using a multimeter to determine the state of charge.
2
Inspect the vehicle's settings to ensure no features such as 'Sentry Mode' or 'Always Connected' are unnecessarily draining the battery.
3
Use a scan tool to check for any error codes related to the battery or electrical systems.
4
Measure the current draw from the battery in sleep mode to identify any excessive parasitic draw.
5
Verify the condition and connections of the 12V battery, as it can affect overall battery performance.
6
Review recent software updates and ensure the vehicle's firmware is up to date.

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
•OBD-II scanner
•Basic hand tools

Parts Required

•12V battery

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Diagnostic Steps

1
Check the battery voltage using a multimeter to determine the state of charge.
2
Inspect the vehicle's settings to ensure no features such as 'Sentry Mode' or 'Always Connected' are unnecessarily draining the battery.
3
Use a scan tool to check for any error codes related to the battery or electrical systems.
4
Measure the current draw from the battery in sleep mode to identify any excessive parasitic draw.
5
Verify the condition and connections of the 12V battery, as it can affect overall battery performance.
6
Review recent software updates and ensure the vehicle's firmware is up to date.

Solution

1. Preparation

Tools Required: Multimeter, OBD-II scanner, basic hand tools.
Ensure the vehicle is parked in a safe location and powered off.
Disconnect the negative terminal of the 12V battery.

2. Inspect Battery Connections

Sub-steps:
- Open the frunk and access the battery compartment.
- Check for any corrosion or loose connections on both the 12V and main battery terminals.
- Clean any corrosion with a mixture of baking soda and water, then reconnect the terminals tightly.

3. Test 12V Battery

Sub-steps:
- Reconnect the negative terminal of the 12V battery.
- Use a multimeter to check the voltage of the 12V battery. It should read around 12.6V or higher.
- If the voltage is below 12.4V, consider replacing the 12V battery.

4. Monitor Parasitic Draw

Sub-steps:
- With the vehicle off, connect the multimeter in series with the negative terminal and the ground.
- Observe the current draw. It should be below 50 mA in sleep mode.
- If the draw exceeds this, systematically disconnect fuses to isolate the circuit causing the drain.

5. Adjust Vehicle Settings

Sub-steps:
- Access the vehicle’s settings via the touchscreen.
- Disable features like 'Sentry Mode' or 'Always Connected' temporarily to see if it affects battery drain.
- Check for any applications or features that may be running in the background.

6. Software Update

Sub-steps:
- Connect the vehicle to Wi-Fi to check for any available software updates.
- Follow on-screen prompts to install updates if available.
- Restart the vehicle after the update is complete.