What Is Level 1, 2, 3 Charging?

If you own a plug-in vehicle or are considering one, you’ve probably been exposed to the terms Level 1, Level 2 and Level 3 associated with charging speeds — not to be confused with the levels of autonomy, which are flawed and of questionable value. Honestly, the numbered charging levels aren’t perfect, either. Below we explain what they mean — and what they don’t. Bear in mind that regardless of the charging method, batteries always charge faster when empty and slower as they fill, and that temperature also affects how quickly a car will charge. All of the levels below apply both to Teslas and other brands, though Tesla has a proprietary connector and the rest of the industry has agreed upon the one known only as J1772 for the SAE International standard that rules all EV charging.

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Level 1

Level 1 represents 120-volt charging using the ubiquitous household outlet. It’s known as trickle charging because it typically provides 3-5 miles of range for every hour it’s connected to an EV or plug-in hybrid electric vehicle (PHEV). Modern PHEVs are EPA-rated with 15-60 miles of electric range, while EVs are between 150-400 miles, so that could mean 30 hours to replenish 150 miles of range at Level 1’s fastest. The amount depends mostly on the vehicle’s efficiency, because a less efficient vehicle gets less range from the same amount of electricity as a more efficient one.

Automakers almost always include with their plug-in vehicles a small Level 1 charger, a small box or cylinder with a short cord, and grounded household plug on one end and a longer cord and the pistol-grip connector that plugs into the car on the other. It’s technically called an EVSE, which stands for electric vehicle service equipment or supply equipment. While it’s the least useful charging level, Level 1 manages to be the most useful designation because there’s little difference in how much juice any of these chargers provide. Typically they’re limited to 10 or 12 amperes of current because there’s an assumption they’ll be used on a 15- or 20-amp circuit along with other electric outlets and, thus, other appliances. Ten versus 12 amps is a difference, but a trickle is still a trickle. You’ll see in the Level 2 description how meaningless a level can be.

Level 1 charging is oftentimes adequate for PHEVs because they have smaller batteries than EVs with no gas backup, but we still recommend Level 2 if it’s affordable because Level 1 doesn’t provide enough power to preheat or precool the cabin in extreme temperatures while still connected to the grid, which is key to preserving battery charge and range.

Note that automakers are increasingly including with their EVs a standard charger that’s more robust, capable of both Level 1 and Level 2 charging. Interchangeable short pigtail cords with different types of plugs determine which level it operates at. This is how Tesla has done it with its Mobile Connector for years, and others are following suit, including Ford with the Mustang Mach-E. With a maximum rating of 32 amps in Tesla’s case (for use on a 40-amp circuit), this type of charger might be more than enough for most owners.

Level 2

Level 2 is the opposite of Level 1: the most useful type of charging and the least meaningful designation. It’s the most useful because it’s the fastest means of charging an EV at home, and doing just that is the only satisfying way to own an EV. Yes, DC fast charging is faster, but that happens only in public and has downsides addressed below.

The only thing Level 2 means is 240 volts, which your house already receives for appliances like a clothes dryer, electric oven or central air conditioner whether you use these items or not. Unfortunately, voltage is just one factor behind the power that charges a battery; current is the second factor, and the amount of current supported by Level 2 extends from 12 to 80 amps. So charging at this “one” level called Level 2 for one hour could mean you’ve added 5.5 miles of range or 60 miles of range. It all depends on the vehicle and the charging unit, which have their own current ratings as we explain in 5 Things That Could Slow Your EV’s Home Charging Speeds.

The Level 2 charger can have a rating of 12, 16, 20, 24, 32, 40, 48 or 64 amps — and some can be set to throttle down to lower current levels to accommodate being fed by less robust circuits.

As noted in the Level 1 section, automakers are increasingly including a combination Level 1/2 charger with interchangeable short pigtail cords that can be plugged into a household 120-volt outlet or one of many styles of 240-volt outlets (you never knew how many there were). In Teslas using its Mobile Connector rated for 32 amps, that’s good for a healthy 30 miles of range per hour in the small Model 3 sedan and 20 miles in a Model X large SUV. The other Tesla models fall in between.

Some competing models are in the same ballpark but often add a few less miles per hour. Don’t be fooled into thinking Tesla’s Mobile or Wall Connectors are “faster” than comparably rated chargers with the type of connector most other EVs now use. If Tesla chargers seem faster, it’s because Tesla vehicles tend to be more efficient than direct competitors, so the same amount of juice equals more range added.

Level 3

There’s no such thing as Level 3 charging. We know, sometimes the truth hurts.

Somewhere along the line, an assumption was made that if Level 2 came after Level 1, then certainly the faster thing must be Level 3, and people started calling DC fast charging “Level 3.” We at Cars.com might have fallen prey to it ourselves. But there’s nothing in the SAE J1772 standard governing such things that calls DC charging “Level 3.” Quite the contrary; like AC charging, DC charging technically has two levels. The SAE proposed a Level 3 both in 1996 and 2001, but one was for DC charging and the other for AC. Neither materialized. So even if a Level 3 were to appear in the future representing DC fast charging, it probably would be for a new, higher rate than what we’ve erroneously called Level 3 in the past.

DC Fast Charging

If we’re honest, even DC fast charging, which includes Tesla Supercharging, isn’t fast when compared with pumping gasoline into a tank. But because it’s capable of adding 10 or more miles a minute in the best cases, it can be much faster than the fastest Level 2 charging.

We won’t go too deep into the science, but in case you’re wondering why DC charging can be so much faster, it’s because DC stands for direct current, which is what a battery accepts directly. We detail in the 5 Things story that any EV’s onboard charger module is a choke point because it has to convert the grid’s alternating current (AC) to DC before it can charge the battery, a process called rectification. Public DC chargers do three things: They start with higher AC voltage than you have at home, rectify it to high-voltage DC outside the car using big, robust equipment that’s often hidden behind shrubbery far from the svelte charging point where you hook up, and then feed it directly to your car’s battery.

For all EVs except Teslas, this requires wiring separate from the Level 1 and 2 circuit — either two additional contacts under the typical J1772 round pistol-grip connector that turn it into the near-standard combined charging system (CCS) connector, or a separate connector like the obsolete CHAdeMO championed by Japanese automakers. Tesla vehicles are designed to switch internally when Supercharging, so they use the same small connector for DC as for AC, just with a larger cable. On the charger end, the CCS connector is so bulky, it can barely be called a pistol style anymore (unless the pistol is a pregnant flare gun).

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The numbers explain why DC charging is so much faster. Once you multiply the amps discussed above with the voltage at hand, the average 32-amp Level 2 charger delivers a maximum of 7.7 kilowatts to the car. Newer EVs are pushing toward higher maximum acceptance rates for AC charging, above 10 kW, and the highest in the Level 2 standard is 19.2 kW. Nowadays, DC chargers rated at 24 or 50 kW are considered the slow ones. The Electrify America network includes some rated at 50, 150 and 350 kW. Tesla Superchargers can be found with ratings of 72, 150 and 250 kW. Let us warn you, however, that we’ve seldom seen EVs charge at their maximum DC ratings even at compatible stations, and the reason is often a mystery.

DC fast charging certainly seems attractive, but it comes with downsides. For one thing, most automakers say either explicitly or hidden in their owner’s manuals that frequent DC fast charging will diminish the battery pack’s longevity. In our experience, even manufacturers that don’t issue such a warning won’t claim that their components are immune; they merely account for it in warranty coverage.

Another downside is the cost. There’s a trend of automakers including free charging at Electrify America stations with the purchase of their EV for the period of two or three years — a substantial incentive, though one that might inspire owners to compromise their battery life in exchange for free fuel. Once this period ends, owners will find DC charging is almost invariably more expensive than home charging, diminishing one of the advantages of going electric.

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