Level 1 vs Level 2 charging: which do you need?

What is the difference between Level 1 and Level 2 charging?

Level 1 means plugging the car into an ordinary 120 V household outlet, usually with the portable cord that comes with it, at just under 2 kW. Level 2 means a 240 V circuit (208 V at many commercial sites), through a wall unit or a higher-power portable one, anywhere from just under 3 kW up to 19.2 kW; the Department of Energy's Alternative Fuels Data Center notes that home units typically draw up to 30 amps and deliver 7.2 kW.

Both are AC charging: the car's onboard charger converts the power for the battery, and that onboard charger caps how fast Level 2 can go. A car that accepts 7 kW will not charge faster on a wall unit rated well above that. What people call Level 3 is DC fast charging, which bypasses the onboard charger and belongs on highway corridors, not in a home garage.

How long does Level 1 and Level 2 charging take?

At about five miles of range per hour, eight hours on Level 1 adds roughly 40 miles. At about twenty-five miles per hour, Level 2 can generally refill a depleted battery overnight, according to the Department of Energy's EV consumer guide.

For your own car, divide the energy you want to add in kWh by the lower of two ratings, the charging unit's and the onboard charger's, to estimate the hours. Level 2 speed in kW is the single most useful figure to look up before buying equipment.

Which is more efficient, Level 1 or Level 2?

Level 2, usually. Charging efficiency is the share of electricity drawn from the grid that actually ends up in the battery, and it matters because the bill counts the grid side. Recurrent summarized studies that measured losses consistently higher on 120 V.

• A 2014 study measured Level 1 at 83.8% efficient on average and Level 2 at 89.4%.
• A 2017 study found about 80% for Level 1 and above 90% for Level 2, around 93% to 95% at higher currents.
• Home charging overall landed between about 83% and 94% from grid to battery.

Is Level 2 charging cheaper than Level 1?

Slightly per mile, and much more expensive up front. Using the 2014 averages, putting 20 kWh into the battery draws nearly 24 kWh from the wall on Level 1 and about 22.4 kWh on Level 2, roughly 6% less electricity billed for the same range. Multiply by your own rate to see what that is worth.

Level 1 usually costs nothing extra because the cord and the outlet already exist. Level 2 equipment runs about $500 to $4000 before installation and incentives, according to the AFDC, and more if the home needs an electrical service upgrade. The energy savings alone rarely pay that back quickly; the real reason to upgrade is time.

Do you need a Level 2 charger at home?

Multiply your usual overnight parking hours by about five miles to see what Level 1 refills, then compare it with a typical day. Ten hours parked adds roughly 50 miles. If you drive less than that on most days, Level 1 keeps up; cold weather, a long weekend trip or a second driver sharing the car are the exceptions that push past it.

Level 1 is often enough for a plug-in hybrid, which the AFDC notes Level 1 can charge overnight, and for a short commute with long nights at home or charging at work. Level 2 is worth it for long daily drives, a large battery, short or unpredictable nights, or a household adding a second EV. Check the onboard charger's AC rating and your electrical panel before buying equipment.

How can you tell if your current setup keeps up?

Your own sessions answer it faster than any average. WrenchTime's charging log records each session's energy in kWh, cost, charger type (Level 1, Level 2 or DC fast), location, battery percentage before and after, and odometer, then shows efficiency in km/kWh, mi/kWh, kWh/100 km or kWh/100 mi, a home charging ratio and a charger type breakdown chart. A few weeks of logged sessions show whether Level 1 refills what you drive and what your real cost per mile is. The EV charging log guide covers the details.