Why does my Tesla app reports lower power received by the battery than the report by the SWTCH EV charger after charging?

It's quite typical to notice differences between the energy reported by a third-party EV charger like SWTCH and what your Tesla app shows. This variation is due to several factors, mainly concerning energy loss and measurement discrepancies. Here’s a summary:

1. Charging Losses:

• Conversion Losses:
  • EV chargers, particularly AC chargers, convert alternating current (AC) from the grid into direct current (DC) for your vehicle's battery. This conversion isn't entirely efficient, leading to some energy loss as heat.   
  • Likewise, the onboard charger in your Tesla experiences internal losses during this conversion.
• Cable Losses:
  • Electrical cables have resistance, which results in some energy being lost as heat during transmission. The longer the cable and the higher the current, the more significant the loss.   
• Battery Thermal Management:
  • The battery management system (BMS) in your Tesla regulates the temperature of the battery. Aside from keeping the car turned on, some energy is utilized to cool or heat the battery, particularly during fast charging. This energy isn't stored in the battery itself.   

2. Measurement Differences:

• Measurement Points:
  • The third-party charger measures the energy it supplies from the grid.
  • Your Tesla app measures the energy that is actually added to the battery. These represent two distinct measurement points, and the difference accounts for the losses mentioned earlier.
• Measurement Accuracy:
  • Both the charger and the Tesla have tolerances in their measurements. There may be minor variations in their accuracy.
• BMS Calculations:
  • Tesla's BMS employs complex algorithms to estimate the battery's state of charge and the energy added. These calculations may differ slightly from the raw energy delivered by the charger.

In simpler terms:

Consider it like filling a bucket with water from a hose. Some water is lost due to evaporation, leaks, and splashing. The water meter at the source measures the total water that flowed through the hose, while you only see the water that's actually in the bucket. The "lost" water represents the energy losses during EV charging.

Key Takeaways:

• It's normal to observe a difference between the energy reported by the charger and your Tesla app.
• Charging losses are a natural aspect of the EV charging process.   
• Measurement differences also play a role in the discrepancy.

So, please don't worry if you notice differences in the reported power.