Comparing the Efficiency of Different EV Charging Types

Recent Posts
California Drivers Express Concern with Lack of EV Charging Stations
ASEAN Sustainable Energy Week 2024
Russia's Increased Investment in Electric Vehicle Charging Infrastructure
The Rise of EV Charging Stations in Nigeria
The Need for Increased EV Charging Infrastructure
Chinese Enterprises Shine at the Smarter E Europe Exhibition
You might not often think about how much of the electricity you pay for actually makes it into your EV's battery, but the reality is, not all of it does. Electricity transmission is inherently lossy. The energy that doesn't reach its destination is primarily lost as heat during the process. Generally, the longer the distance electricity has to travel, the greater the losses. Moreover, electricity is more efficiently transmitted at higher voltages, which helps minimize these losses. Most electricity wastage occurs after it's been converted from high-voltage lines (which can carry tens of thousands of volts) to the lower-voltage lines used in residential areas (120 volts in the US and 240 volts in Europe). Losses also occur when electricity is stepped down through substations and when it's converted from alternating current (AC), used by the grid, to direct current (DC), required to charge your EV. To truly understand the efficiency of EV charging, consider fully draining your EV's battery and then charging it to full capacity. You might be surprised to discover that it takes about 10% more electricity than the battery's rated capacity to recharge it completely. This extra consumption is due to charging losses. A practical example of this was illustrated by ADAC in Germany during a test with a new BMW iX. Using a 22 kW AC wall charger in a 73.4°F environment, it was found that charging the iX’s 105.2 kWh battery required about 125.2 kWh. This results in a loss of roughly 20 kWh or 20%, aligning closely with the typical 15% loss expected in EV charging. Tesla’s certification documents with the EPA, highlighted by Car and Driver, provide another case. To fully charge a Model Y Performance’s battery, which was entirely depleted, with a 240-volt Level 2 charger, it needed 92.2 kWh instead of the anticipated 81 kWh, indicating a 14% loss. Several factors contribute to charging losses, especially with AC (Level 1 or Level 2) chargers. These include the onboard AC-to-DC converter in the EV, the charger and charging cable, the battery's thermal management system, and the charging power. Losses occur due to a mix of "transmission losses," heat dissipation, and energy used to maintain optimal battery temperature during the charging process. ADAC's investigation into EV charging efficiencies uncovered significant differences between charging methods. When the Renault Zoe, a model lacking battery thermal management, was charged directly from a standard household outlet, the losses amounted to 24.2%. However, these losses drastically reduced to 9.7% when utilizing an 11 kW wall box for charging. Although the extent of the losses varied across different vehicle models tested, the trend consistently showed reduced losses with the use of a dedicated wall-mounted charger compared to a standard outlet. The scenario shifts when utilizing a Level 3 DC fast charger, which bypasses the need for AC to DC conversion, theoretically reducing energy losses. Precise data on the efficiency of DC fast charging is less available, but estimates suggest losses could be around 10%. Tom Moloughney provided a practical example from his experience fast-charging his Tesla Model 3. Starting from a 7% state of charge, he used an Electrify America station with a CHAdeMO to NACS adapter to increase the charge to 57%, which equated to adding approximately 35.5 kWh to the battery. He estimated losses at about 3.5 kWh for this charging session, predicting that charging from completely depleted to full would result in total losses of around 7 kWh, or roughly 10% of the battery's usable capacity at the time. It's speculated that charging losses could be even lower when a fast charger and EV, both operating at 800 volts, are paired, although this theory awaits empirical validation to confirm exact efficiency gains. For EV owners worldwide, it's important to recognize that when charging their vehicle, the cost also covers the electricity that doesn't make it into the battery due to losses, mostly manifesting as heat. To reduce such losses, it's advisable to steer clear of Level 1 charging, which is typically the least efficient method. While Level 3 DC fast charging presents the most efficient option with minimal losses, it's also associated with quicker battery wear over time. Therefore, although it's convenient for rapid charging needs, relying on it regularly is not recommended for those aiming to maintain their EV's battery health and longevity.

You might not often think about how much of the electricity you pay for actually makes it into your EV’s battery, but the reality is, not all of it does.

Electricity transmission is inherently lossy. The energy that doesn’t reach its destination is primarily lost as heat during the process. Generally, the longer the distance electricity has to travel, the greater the losses. Moreover, electricity is more efficiently transmitted at higher voltages, which helps minimize these losses.

Most electricity wastage occurs after it’s been converted from high-voltage lines (which can carry tens of thousands of volts) to the lower-voltage lines used in residential areas (120 volts in the US and 240 volts in Europe). Losses also occur when electricity is stepped down through substations and when it’s converted from alternating current (AC), used by the grid, to direct current (DC), required to charge your EV.

To truly understand the efficiency of EV charging, consider fully draining your EV’s battery and then charging it to full capacity. You might be surprised to discover that it takes about 10% more electricity than the battery’s rated capacity to recharge it completely. This extra consumption is due to charging losses.

A practical example of this was illustrated by ADAC in Germany during a test with a new BMW iX. Using a 22 kW AC wall charger in a 73.4°F environment, it was found that charging the iX’s 105.2 kWh battery required about 125.2 kWh. This results in a loss of roughly 20 kWh or 20%, aligning closely with the typical 15% loss expected in EV charging.

Tesla’s certification documents with the EPA, highlighted by Car and Driver, provide another case. To fully charge a Model Y Performance’s battery, which was entirely depleted, with a 240-volt Level 2 charger, it needed 92.2 kWh instead of the anticipated 81 kWh, indicating a 14% loss.

Several factors contribute to charging losses, especially with AC (Level 1 or Level 2) chargers. These include the onboard AC-to-DC converter in the EV, the charger and charging cable, the battery’s thermal management system, and the charging power. Losses occur due to a mix of “transmission losses,” heat dissipation, and energy used to maintain optimal battery temperature during the charging process.

ADAC’s investigation into EV charging efficiencies uncovered significant differences between charging methods. When the Renault Zoe, a model lacking battery thermal management, was charged directly from a standard household outlet, the losses amounted to 24.2%. However, these losses drastically reduced to 9.7% when utilizing an 11 kW wall box for charging. Although the extent of the losses varied across different vehicle models tested, the trend consistently showed reduced losses with the use of a dedicated wall-mounted charger compared to a standard outlet.

The scenario shifts when utilizing a Level 3 DC fast charger, which bypasses the need for AC to DC conversion, theoretically reducing energy losses. Precise data on the efficiency of DC fast charging is less available, but estimates suggest losses could be around 10%.

Tom Moloughney provided a practical example from his experience fast-charging his Tesla Model 3. Starting from a 7% state of charge, he used an Electrify America station with a CHAdeMO to NACS adapter to increase the charge to 57%, which equated to adding approximately 35.5 kWh to the battery. He estimated losses at about 3.5 kWh for this charging session, predicting that charging from completely depleted to full would result in total losses of around 7 kWh, or roughly 10% of the battery’s usable capacity at the time.

It’s speculated that charging losses could be even lower when a fast charger and EV, both operating at 800 volts, are paired, although this theory awaits empirical validation to confirm exact efficiency gains.

For EV owners worldwide, it’s important to recognize that when charging their vehicle, the cost also covers the electricity that doesn’t make it into the battery due to losses, mostly manifesting as heat. To reduce such losses, it’s advisable to steer clear of Level 1 charging, which is typically the least efficient method.

While Level 3 DC fast charging presents the most efficient option with minimal losses, it’s also associated with quicker battery wear over time. Therefore, although it’s convenient for rapid charging needs, relying on it regularly is not recommended for those aiming to maintain their EV’s battery health and longevity.

Leave a Reply

Your email address will not be published. Required fields are marked *