I’ve been charging EVs at home for almost 7 years — but you need to be careful during summer heat waves

Spring is in full swing, bringing rising temperatures and unseasonable heatwaves. While the warm weather is welcomed by most, if you're an EV owner who charges at home, there are specific precautions you need to take.

I've owned an EV for nearly seven years now. My journey started with a Tesla Model 3, followed by a Rivian R1S for the family, and most recently, I traded the Tesla for a Ford F-150 Lightning.

Charging at home is incredibly convenient and cost-effective, but I’ve learned plenty of hard lessons over the years — the biggest being how to handle charging at home during extreme heat, much like what’s going on with the east coast right now.

The very real headache of overheating chargers

Three years ago, we began having problems charging my Tesla Model 3 and my wife's Rivian R1S during the summer. Temperatures were routinely reaching over 100°F during the day, but the last thing on my mind was that the ambient heat in our garage was causing issues with our EV charging setup.

After several days of troubleshooting random alerts — ranging from the Rivian's charging rate being reduced to 5 kW to the Tesla's charging stopping and restarting entirely — I contacted Tesla support.

The answer? My 98°F garage was causing the unit to overheat and throttle its charging speed to prevent damage to the car, the wall connector, or both. For the Tesla Wall Connector specifically, an ambient temperature over 95°F can be problematic.

The same is true for all EV chargers. When ambient temperatures lead to operating levels outside a charger's specified range, the hardware or the vehicle will take measures to protect itself.

Complicating matters is the use of adapters, some of which come from questionable brands on Amazon. We were using an adapter from what I thought was a reputable manufacturer, yet it would get too hot to touch even on mild days. At one point, my infrared thermometer clocked it at over 135°F.

Eventually, I upgraded our home setup to a Tesla Universal Wall Connector. While this fixed the issues with the overheating adapter, we still have to account for those high ambient temperatures.

How to Charge Your EV Safely and Cheaply This Summer

When the summer heat officially arrives, we take a few precautions at home to avoid hardware issues. The first thing we do is lower the charging rate from the full 48 amps supported by the Tesla Wall Connector down to 32 amps. We do this directly in the Tesla and Rivian app settings rather than diving into the Wall Connector’s internal configuration.

By lowering the amperage, we significantly reduce the amount of heat produced. You can adjust your own charge rates to better suit your specific setup, but keep in mind that it will take longer to reach a full charge — so adjust your expectations accordingly.

Because of that longer lead time, we set our schedules for the coolest part of the day, typically between 10 p.m. and 7 a.m. That nine-hour window is almost always sufficient to top off either of our vehicles. On the rare occasions we've used more battery than can be replenished overnight, we simply start the session manually earlier in the evening.

It might sound silly, but we also place a cheap fan near the car and point it directly at the charge port and adapter. I've tested the results with an infrared thermometer, and the airflow almost instantly drops the handle temperature by 20 to 30 degrees.

This year, I'm taking it a step further by setting up a simple home automation to trigger the fan when the garage reaches 90°F. I’m using an Eve Weather monitor to trigger a Shelly Plug Gen4 connected to the fan.

Another quick tip: don't leave the charging cable coiled up. The cable naturally produces heat during a session, so if it’s bunched up on the ground or wrapped tightly around the charger, that heat stays trapped — inevitably increasing the temperature of the entire system.

Bottom line

Charging your EV at home and waking up to a full battery is one of the primary benefits of the EV lifestyle. However, it does require some planning to do so safely. It only takes a few minutes to adjust your charging habits during a heatwave to protect your hardware, your vehicle, and your home.

By lowering your charge rate, allowing for more time, and scheduling sessions for the cooler overnight hours, you can ensure your setup stays efficient even when temperatures get high.

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