Tesla is known for its fast-charging ability, which helps drivers overcome range anxiety and enjoy the convenience of electric vehicles. However, you may have noticed that your Tesla charging speed is not always consistent, and it tends to slow down over time.
The most common reasons why Tesla’s charging speed slows down are low temperatures, the battery’s state of charge, the car’s maximum charging speed, mismatched circuit and breaker, the charger and Tesla’s amp rating, and limitations in charging stations.

Why Does Tesla Charging Slow Down?
There are several factors that affect Tesla’s charging speed. Here are some possible reasons and explanations:
1. Low Temperatures
One of the main factors that affect Tesla’s charging speed is the ambient temperature.
When the temperature is too low, the battery needs to be warmed up before it can accept high power. This can reduce the charging speed significantly, especially if you are using a Supercharger.
Solution:
To avoid low-temperature issues, you can preheat your battery before you arrive at the charging station by using the Tesla app or by setting a scheduled departure time. You can also park your car in a garage or a warmer place if possible.
2. Battery’s State of Charge (SOC)
Another factor that influences Tesla’s charging speed is the battery’s state of charge, or how full it is.
As the battery gets closer to 100%, the charging speed slows down to protect the battery from overcharging and degradation. This is normal and happens with all lithium-ion batteries, not just Tesla’s.
Solution:
To optimize your charging time, you can charge your battery to 80% or 90% instead of 100% unless you need the extra range for a long trip.
You can also use a lower power charger, such as a Level 2 charger, for the last 10% or 20% of the charge, as it will be more efficient than a Supercharger.
3. The Tesla’s Maximum Charging Speed
Different Tesla models have different maximum charging speeds, depending on their configuration and battery size. For example, the Model 3 Long Range can accept up to 250 kW of power from a V3 Supercharger, while the Model S 100D can only accept up to 150 kW.

The maximum charging speed also varies depending on the software version and updates.
Solution:
To utilize your Tesla’s maximum charging potential, you need to find out your Tesla’s maximum charging speed. You can check the Tesla website or the owner’s manual.
You can also use a third-party app, such as Teslafi, to monitor your charging speed and history.
4. Mismatched Circuit and Breaker
If you are charging at home using a Level 2 charger, such as a Mobile Connector or a Wall Connector, you need to make sure that your circuit and breaker match the charger’s amp rating.

For example, if you have a 48-amp Wall Connector, you need a 60-amp circuit and breaker to support it. If your circuit or breaker is lower than your charger’s amp rating, your charging speed will be limited by the weakest link.
Solution:
To fix this, you can upgrade your circuit or breaker to match your charger’s amp rating or lower your charger’s amp rating to match your circuit or breaker.
5. The Charger and Tesla’s Amp Rating
Another factor that affects your home charging speed is the amp rating of your charger and your car. The amp rating determines how much current can flow through the charger and the car’s onboard charger.
For example, if you have a 32-amp Mobile Connector and a Model 3 with a 48-amp onboard charger, your charging speed will be limited by the Mobile Connector’s amp rating.
Solution:
To maximize your home charging speed, you need to use a charger that has an equal or higher amp rating than your car’s onboard charger.
6. Limitations in Charging Stations
Sometimes, the reason why your Tesla charging slows down is not related to your car or your charger, but to the charging station itself.
Occasionally, grid constraints or other issues, like numerous chargers sharing power at one spot, may prevent a fast charger from providing its full potential. This can happen with both Superchargers and third-party chargers, such as Electrify America or ChargePoint.

Solution:
To avoid charging station limitations, you can check the availability and status of the charging stations before you arrive using the Tesla app or other apps or websites such as PlugShare or A Better Route Planner.
You can also choose a less crowded or less busy time to charge your car.
Related Post: How Much Does A Tesla Battery Weigh?
Frequently Asked Questions [FAQs]
Why does my Tesla charge slowly in low temperatures?
Tesla charging can slow down in low temperatures because lithium-ion batteries, which Tesla uses, have reduced efficiency in cold weather.
Why does Tesla charging slow down as the battery nears full capacity?
When a battery gets close to its maximum capacity, Tesla reduces the charging pace to prevent harm.
Why does my Tesla’s charging slow down with different types of batteries?
Over time, the specific type of battery in your Tesla also affects charging speeds. Li-ion NCA, LFP, 2170, and 4680 cells, for example, charge at various rates.
Why does my Tesla’s charging slow down when using a specific charger?
If you have a lower-powered charger, it will take longer to charge your Tesla.
Why does my Tesla’s charging slow down when the state of charge gets closer to 80%?
Overheating is a result of the thermal runaway issue with lithium-ion batteries. Thus, when the state of charge is high enough, all lithium-ion battery manufacturers limit the charging rate to optimal values.
Related Post: How to Calibrate Tesla Battery Management System?