What Are the Factors Slowing Down Your EV’s Home Charging Speeds?

Have you ever noticed that your electric vehicle (EV) charges slower than expected? While it might seem like a simple issue, there are several factors that can contribute to slower home charging speeds. In this article, we will explore the most common causes, including undersized extension cords, battery state of charge, battery temperature, and potential issues with your electrical system. We will also discuss how to optimize your charging experience for the best results.

Undersized Extension Cords: The Most Common Culprit

Undersized extension cords are the leading cause of slow home charging speeds. These cords restrict the amount of power that can be transferred, resulting in a significantly reduced charging rate. This is a critical issue that needs immediate attention, as using undersized cables can damage your vehicle's charging system and potentially harm your home's electrical system as well.

Understanding Your Charging Setup

To provide a clear context, we will assume that you are currently fast charging, which is known as Level 2 charging. This involves a 200-240 Volt plug and a 40-amp breaker, providing a charging rate of 6 to 8 kW. However, you might experience reduced charging speeds at times, which can be attributed to several factors. Here’s a breakdown from the most likely to the least likely causes:

Battery State of Charge

The state of charge (SOC) of your battery plays a significant role in charging speeds. As the battery gets closer to a full charge, typically when SOC is around 90%, the charging speed will naturally decrease. This is a designed feature for safety and to maintain the longevity of the battery. The charging controller intelligently manages the charging process to ensure optimal battery health.

Battery Temperature

If the battery temperature is either too cold or too hot, the charging controller will adjust the charging speed to prevent damage to the battery. This is a safety feature that helps maintain the battery’s life and performance. If your battery is in a temperature-controlled environment, such as a garage or climate-controlled space, you can reduce the likelihood of these issues.

Charging Settings

Some users may have limited the charging amps in their settings. For instance, in a Tesla, you can choose to charge at a lower amp rate to slow down the charging process. This is a user-friendly option that allows for more control over the charging rate.

Electrical System or Electric Company Issues

Issues with your electrical system at home, such as problems with your wiring or the amperage of your service, can also slow down charging speeds. According to Tesla, the supported AC charging voltage is between 85V-265V, and the charging speed will be very slow at the lower end of this range. If you are experiencing slow charging due to supply issues, it is advisable to contact your electric supply company immediately.

Issues with the Battery Itself

If you have eliminated all other possible causes, the issue might be with the battery itself. For older non-Tesla EVs, this is a higher possibility. In such cases, it is recommended to get the battery inspected by a professional mechanic.

Optimizing Your Charging Experience

The type of charger you use can also significantly impact your charging speed. A typical trickle charger, like the one that comes with some EVs, is around 1.5 kW, which is a very slow charging rate. For faster home charging, consider installing a Level 2 charger. A 32-amp charger, for instance, can provide a maximum charging rate of 6.6 kW. Conversely, a 15-amp charger would only deliver a speed of 3.3 kW, effectively doubling the charging time.

To achieve the fastest charging rate possible, ensure that your charger’s amperage rating does not exceed what your EV can handle. Check your vehicle’s manual to determine the maximum charging rate it can achieve. This will help you choose the appropriate charger and maximize your charging efficiency.

By understanding the factors that can affect your home charging speeds and taking appropriate actions, you can ensure that your EV is charged efficiently and safely. Whether it's addressing a simple issue with your cords or making adjustments to your electrical setup, taking proactive steps can significantly improve your EV's charging experience.