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Mercedes Wanted $20,000 to Fix This Tesla-Powered EV… I Used a bottle cap
Rich Rebuilds
Overview
This video documents an ambitious 24-hour challenge to repair a neglected, Tesla-powered Mercedes B-Class EV that was abandoned and left to deteriorate. The presenter, working with limited tools and time, diagnoses and attempts to fix various issues, including a dead 12-volt battery, a faulty DC-to-DC converter, and significant coolant intrusion into the drive motor. The repair process involves scavenging parts, improvising solutions like using a bottle cap to seal a leak, and ultimately replacing the drive motor with a Tesla unit. Despite numerous setbacks and the car's poor condition, the presenter manages to get the EV operational, albeit with some lingering issues, fulfilling the terms of a bet.
How was this?
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Chapters
- The presenter accepts a 24-hour challenge to fix a Tesla-powered Mercedes EV that was abandoned and covered in snow.
- A bet is made: if the car is fixed, the friend must drive it 1,500 miles home; if not, the presenter must.
- The car was deemed unfixable by both Tesla and Mercedes, with Mercedes quoting $20,000 for repairs.
- The vehicle is found to be in poor condition, buried in snow, with a dead 12-volt battery and seized brakes.
This chapter sets the stakes and introduces the core problem: a complex, neglected EV with significant repair challenges, highlighting the difficulty and urgency of the task.
The presenter and his friend struggle to even identify the car under the snow, mistaking ice for a mirror and finding a birthday cake inside.
- The initial step is to address the dead 12-volt battery, which powers the car's essential electronics.
- The presenter improvises by purchasing a used toolkit from a pawn shop.
- Testing reveals the 12-volt battery voltage is critically low (1.4V), confirming it needs charging or replacement.
- After jump-starting the 12-volt battery, the car's interior lights and dashboard indicators turn on, signifying a small victory.
Understanding and restoring the low-voltage system is crucial for any EV's basic functionality, enabling diagnostics and further repair attempts.
The presenter tests the 12-volt battery with a multimeter, showing a reading of 1.4 volts, demonstrating its complete failure.
- The car fails to charge, displaying an error message indicating the charge cable is connected when it is not.
- A thorough check of fuses reveals no blown fuses, suggesting a more complex electrical issue.
- Diagnostic scans reveal numerous error codes, including critical faults related to the Battery Management System (BMS) and high-voltage system shutdown.
- A key error code points to a potential DC-to-DC converter failure, which acts as the car's alternator.
This chapter details the process of uncovering deeper electrical problems beyond the initial battery issue, using diagnostic tools to identify the root causes of the car's failure to operate.
The diagnostic tool displays 21 error codes, overwhelming the presenter and highlighting the complexity of the car's issues.
- The presenter suspects the DC-to-DC converter is the primary cause of cascading errors, as it's responsible for charging the 12-volt battery from the high-voltage pack.
- Accessing the converter involves removing protective shielding and dealing with tight, German-engineered components.
- Upon disassembly, the converter is found to have water intrusion, likely from its previous exposure to snow and moisture.
- The presenter replaces blown fuses within the converter and meticulously cleans and reseals the unit, using silicone sealant to prevent future leaks.
This section demonstrates the importance of component-level repair and troubleshooting, especially when dealing with water damage in automotive electronics.
The presenter discovers water damage inside the DC-to-DC converter, with coolant seeping into the electrical components, necessitating a thorough cleaning and resealing process.
- Despite repairing the DC-to-DC converter, a new issue arises: a high-voltage isolation fault.
- This fault is traced to coolant intrusion into the front drive motor, a known problem with these Tesla-based units.
- The presenter performs a 'coolant delete' by cutting a coolant tube and sealing the opening with a bottle cap and RTV sealant, a makeshift but effective solution.
- The original drive motor is replaced with a used Tesla Model S drive unit, and the car is reassembled.
This chapter showcases advanced repair techniques, including component replacement and creative, 'ghetto' fixes, to overcome a critical failure in the EV's powertrain.
The presenter cuts a coolant tube leading into the drive motor and uses a plastic bottle cap sealed with RTV silicone to block the coolant flow, preventing further intrusion.
- After repairs, the car starts, displays no errors, and successfully engages in 'drive' mode, moving the vehicle.
- The presenter confirms the DC-to-DC converter is functioning by measuring its output voltage.
- The car is able to charge, indicating the previous charging issue was resolved.
- The presenter and his friend take the car for a test drive, experiencing its Tesla-powered acceleration and overall performance, ultimately winning the bet.
This concluding chapter demonstrates the success of the repair efforts, validating the presenter's unconventional methods and the car's newfound functionality.
During the test drive, the car performs a burnout, showcasing its surprising power and confirming the success of the repairs.
Key takeaways
- Complex EV repairs can sometimes be achieved with unconventional methods and salvaged parts, even when official repair channels are prohibitively expensive.
- Water and coolant intrusion are significant threats to automotive electronics, requiring meticulous sealing and protection.
- The 12-volt battery is critical for EV operation, and its failure can prevent any diagnostic or system activation.
- Understanding the function of components like the DC-to-DC converter is essential for diagnosing EV electrical issues.
- Cascading errors in complex systems mean that fixing one problem can reveal or resolve others, but a single failure point can cause widespread issues.
- Creative, 'ghetto' repairs, while not ideal, can be effective temporary solutions to get a vehicle operational.
- The integration of Tesla technology into other manufacturers' vehicles highlights the evolution and shared components within the EV industry.
- Thoroughness in cleaning and sealing is paramount, especially after water damage, to prevent recurring problems.
Key terms
DC-to-DC converter12-volt batteryHigh-voltage isolation faultCoolant intrusionBattery Management System (BMS)Drive motorContactorsCharge cable lockoutRegeneration (Regen)RTV sealant
Test your understanding
- What is the primary function of a DC-to-DC converter in an electric vehicle, and why is it crucial for diagnosing this specific car's issues?
- How did water intrusion specifically affect the DC-to-DC converter and the drive motor, and what were the consequences of these issues?
- Describe the presenter's 'ghetto' repair for the coolant leak in the drive motor. Why was this necessary, and what materials were used?
- What were the initial symptoms of the car being dead, and how did the presenter systematically diagnose and address the low-voltage system problems?
- Explain the concept of cascading errors in EVs, using the example of the DC-to-DC converter failure in this video.