The Virtues of Oft-Neglected Level-1 EV Charging

Trickle Charging: The Simple and Easy Solution for At-Home EV Charging

Media, policymakers and consumers all focus their EV charging attention on innovations in level 3 DC fast chargers. This is with good reason—the technology soon promises to charge an EV in about the same time required to fill a VICE (Vehicle with an Internal Combustion Engine) with gas.

We’ve talked a lot about fast charging, including in our reports about our 2,000-mile road trip to Houston and our 1,000-mile journey up the Atlantic Coast towing our Aliner Scout.

At home, most people assume they need the latest, fastest level-2 chargers, now capable of delivering 19.2 kW, allowing a car to charge in three to five hours.

With all this attention focused on the fastest solutions, people too often ignore the easiest, simplest and cheapest solution: level 1 charging, often derisively called “trickle charging.”

We’ve been driving EVs for about five years now. We’ve never had access to a level-2 charger at home. We’ve rarely missed it. Today, we’ll tell you why.

When we parked our car in a shared garage, there was a regular 120 outlet about 25 feet from our vehicle. With a standard extension cord and the level 1 charging adapter that came with the EV, we could simply plug the car in and charge.

We regularly paid the HOA for our estimate of the energy used.

Now, our condo has a private two-car garage. Such luxury! We have two 120 outlets in the garage, one for each EV we hope to own.

As we work from home, we don’t have a commute that keeps our car out of the garage all day. On the contrary, we average about 22 hours per day at home, giving us ample time to charge. But most of the time, we don’t need it.

With our Bolt, we can set the car to charge at eight or 12 amps when plugged into a level 1 charger. That was not an option with our 2012 Nissan Leaf. We don’t know if it is on a Tesla Model S, but for the sake of this comparison, we assumed it is.

The chart below provides perspective.

We can add 46 miles to our Bolt in 12 hours overnight, even at the 8-amp rate. By choosing the 12 amp rate, we can make that 69 miles. So, if we did have a commute that had the car outside the home for 12 hours per day, we could still go 34.5 miles each way and wake each morning with a full battery.

Until I began running the numbers for this piece, I hadn’t fully appreciated that while the Tesla Model S can charge radically faster on DC faster chargers like Tesla provides with its Superchargers or Electrify America delivers with its 350 kW chargers, the Bolt adds more miles per minute on almost all other chargers. Take a look at this chart.

The simple reason is that the Model S is less efficient and has a much bigger battery.

The Model S’s ability to charge from 20% to 80% in about 20 minutes is fantastic. By the time you use the restroom, buy a snack and get back to the car, you’ve got 240 miles of range ready to use.

If you’re not charging at the fastest chargers, however, the Bolt will add more miles per minute. When estimating charge times, I’ve made an attempt to adjust the charging rates because no EV can charge at the peak rate from 20 to 80 percent, much less from nearly empty to full. The Tesla maintains a charging rate closer to the peak rate than the Bolt, even though the Bolt has a much lower peak rate.

Still, after attempting to adjust for that, the Bolt adds more miles per minute on every charger of 50 kW or less. Check my math here.

That said, even if you have a Tesla, you could add at least 35 miles per night if you have a commute that keeps the car away from home half the time. That distance allows for many commutes. If you work from home and can charge 22 hours per day, you can drive 63 miles daily in your Tesla and still wake up each morning to a full charge.

So-called trickle charging won’t work for everyone, but for many, it eliminates the need to have an electrician add a 240-volt outlet in your garage, and you won’t have to buy a charger to go with it. While that cost is small relative to the cost of the car, it is large compared with the cost of powering it.

If you spend a relatively small amount, say $1,000, to get the charger and have it installed, that would buy up to ten megawatt-hours of energy for your car—depending on rates in your community. That’s enough to drive a Bolt 40,000 miles or a Tesla Model S about 30,000 miles.

Occasionally, we need to have a full charge in the morning after driving a lot and returning home with an empty battery. When that happens, we visit a local level 3 charger before we put the car to bed for the evening. As you know, we travel a lot, but that has happened only about four or five times this year.

Most EV drivers we know like to wake up with a pretty full battery. We charge ours to 90 percent. Some EV drivers keep their vehicles at a lower state of charge as part of a strategy to preserve the battery’s life. If you’re in that group, the level 1 charging approach may work even better. Note, too, that some people smarter than I have suggested that lower charging speeds are easier on your battery.

Before you plunk down a bunch of cash for a level 2 charger at home, consider trying the old-school level 1.