If your home EV charger seems to be charging slower than you expected, there is usually a clear reason, and it is often not a fault at all. The most common causes are the charger’s amperage, your car’s onboard charging limit, cold weather, and charging settings. Working through the possibilities helps you figure out what is going on.
Here is why your home EV charger might be charging slowly.
Your car’s onboard charger sets the limit
The most common reason is your vehicle’s onboard charger. Every EV has an onboard charger that limits how much power it can accept, and if that limit is lower than your charger’s output, the car charges at its own slower rate. For example, if your car accepts a maximum of 7.7 kW, it will charge at that rate even on an 11.5 kW charger. This is not a problem with your charger, it is simply the car being the bottleneck.
The charger’s amperage or settings
How fast your charger can deliver power depends on its amperage and how it is configured:
- A lower-amperage charger or circuit delivers less power and charges more slowly.
- Smart chargers can be set to a lower charging rate, sometimes without you realizing it.
- If load management is active, the charger may reduce its rate when your home is drawing heavily.
Checking your charger’s settings and configured amperage can reveal an easy fix.
You might be on Level 1, not Level 2
If your charging is very slow, adding only a few miles per hour, you may be charging on a standard 120-volt outlet rather than a 240-volt Level 2 circuit. Level 1 charging is dramatically slower. If you thought you had Level 2 but are seeing Level 1 speeds, it is worth confirming your setup with an electrician.
Cold weather
Cold weather slows charging because a cold battery accepts a charge more slowly, and the car may limit the rate to protect it. This is temporary and battery-related, not a charger fault. Preconditioning the battery and charging while it is still warm from driving help restore speed on cold days.
The battery’s state of charge
Charging naturally slows as the battery approaches full, since the car tapers the rate to protect the cells. If you are noticing slow charging in the last stretch toward 100 percent, that is expected behavior, not a problem.
When to call an electrician
Most slow-charging causes are explained by the factors above. But if your charging speed suddenly drops, or you see signs of a problem such as warm connections, tripping breakers, or the charger behaving abnormally, it is worth having a licensed electrician check the circuit and connections. A loose or failing connection can reduce performance and is a safety concern.
A home EV charger usually charges slowly because of your car’s onboard charging limit, the charger’s amperage or settings, cold weather, or the battery nearing full, and sometimes because you are actually on a slower Level 1 outlet. Most of these are normal or easily adjusted. If the slowdown is sudden or paired with warning signs like warm connections or tripping breakers, have a licensed electrician inspect the circuit.
Stella Electric installs and troubleshoots home EV chargers for homeowners across the Baltimore area and throughout Maryland, with flat-rate pricing and no overtime charges. If your charging seems off, we can check your setup. Financing is available on qualifying projects.
