Leaf Charging

Nissan leaf charging

Nissan Leaf charging with Level 3

(Slightly technical post but potential EV buyers (everyone!!??) might be curious.)

I was pondering exactly how we will charge the new Leaf when we get it, and I realized that I didn’t quite understand how the charging and chargers work. You can charge at home with a standard 110v wall outlet, and we will be able to do this in the summer with extra solar power. But for the rest of the year I’m going to need to augment this by charging at work, or my wife will have to take it and charge at her work. The easiest way to do this would be with regular 110v wall power, a “Level 1” charge.

The Level 1 charge is somewhat slow, though, I could expect about 4 or 5 miles of range for each hour I charged. Not bad; 40 miles worth of charge in an 8-hour work day, but not enough for me to drive 40 miles each way. I suspect that most people don’t drive 80 miles a day, and do have access to grid power. For them, I’m pretty sure the Level 1 might be all they would need at their house or work.

But I might need Level 2 charging, or a 220v charger, due to my unusual combination of solar power and longish commute. Here’s where the questions begin—the chargers cost about $900, and need to be hard-wired to a wall (vs. using a 220v plug into a clothes dryer socket). So what do the chargers DO that makes them cost that much? So, I’ll just cut to the end of the story—they don’t do that much; they’re essentially glorified extension cords. The AC power in both Level 1 and 2 charging is delivered straight to the car, to the same charge port.

So I’ll come back to the wall “chargers” in a second, but first—the car senses how much AC voltage is present at the charge port/plug, and automatically uses it to charge the batteries, by converting it to DC with an inverter, and using a computer to track charge rates, etc. But how fast it can charge the batteries depends on whether 110v or 220v is coming in, but ALSO on the size of the onboard (built-in/car) charger. The base model 2013 Leaf has a 3.3 kw onboard charger. This is what gives you the 5 miles of range per hour of charging with 110v, and it gives you about 12 miles of range per hour of charging with 220v. In our situation, where for part of the year we might be making heavy use of public charge stations while we shop in one town or the other, 12 miles of range per hour of charging might not quite be practical enough. So, the base model Leaf, the S, does have an option for the bigger on-board charger, the 6.6 kw version. This seems to be somewhat of the industry standard right now; it’ll give you about 20 miles of range for each hour on the charger with 220v coming in (Level 2). If you own a Leaf, it will fill it up in about 4 hours.

And, one more thing before I return to the wall chargers—the SV and SL Leafs come with a second input port/plug, a “Quick Charge” port, for Level 3 charging. It’s really big, about 3 inches across. This is for the very special and very expensive 440v DC fast-charge stations going in in places like California, where you can charge a Leaf to 80% capacity in 30 minutes. But there aren’t any anywhere close to here, so for me I don’t really need that fast-charging port. It apparently is very slightly hard on the batteries to charge them this fast all the time; Nissan says you might experience 10% more battery life loss over time than normal if you fast-charge regularly.

So back to those $900 glorified extension cords/wall chargers. The NEC (National Electric Code) people got involved when they were setting the standard, and mandated most of this, which is related to why they’re so expensive. So here’s what they do—

1) They deliver the 220v wall power to the car, but they have a sensor that tells the wall charger whether the output cord is plugged into the car or not, so there’s no power in the plug-in cord until you plug it into the car, and if you unplug it, it cuts the power. This is a safety feature in case someone dropped the cord into a puddle, or backed a car out without unplugging it and ripped the wires out and exposed them.

2) They can sense when the car battery is full. I’m pretty sure they don’t communicate with the car, but just sense the amperage that the car is drawing (as the batteries get full the car charger will taper off the charge amperage). So they have a light on them that indicates that the car is “full”

3) They can be set to cap how much amperage that the car can pull, for example, in case the wall charger is capable of delivering 30 amps, but is wired into a 25 amp circuit.

And the reason they have to be hard-wired in also has to do with the NEC people—the Code is apparently pretty strict about 220v plugs that need to be plugged and unplugged regularly; it’s not like a dryer or an oven that you plug in and leave there for ten years. If peoples’ wall chargers were portable, they might unplug them, set them in the trunk, and plug them in somewhere where they were going. Which would be mighty practical, but the NEC didn’t like the idea.

So, we get $900 extension cords called “Level 2 wall chargers,” that most people will then have to pay an electrician to install. Everyone seems to agree that they’re way overpriced, and at least two types of work-arounds seem be out there, if I understood correctly—people who rig up an actual 220v cord with a dryer plug on one end and a charge port plug on the other, and another group who will modify your factory 110v charging cable for about $250; the finished version has all the safety features but can be plugged into a 220v outlet. I’m not sure how recommended either approach is.

At least one company, Leviton, does make Level 2 chargers that plug into outlets, but be careful here, too, apparently there are at least 3 common 220v plug arrangements, including something called a “twist-lock” plug with is supposed to be safer, though I don’t suppose adapters would be all that difficult to acquire. (Unless the outlets are wired differently, I know the old-style 220v outlets had 3 conductors, but the new ones have 4).

For me, we have a 4.4 kw inverter in our off-grid house, so we don’t need to worry about Level 2 charging at home because the inverter couldn’t handle 6.6 kw of draw. And it seems that at work the Level 1 charging would be super-simple, but the Level 2 might not be. So I think we’ll be using Level 1 at work and home, and Level 2 at public charge stations.

I’ll continue to ponder; I think we can use the Leaf without needing to buy a Level 2 charger and trying to get it installed somewhere. I suspect that the prices will come way down soon, anyway. But I do need to try and find an S model that has the 6.6kw on-board charger option installed.

In all honesty, in our somewhat unusual situation, a Chevy Volt with its back-up engine would be more practical, but I’d rather be a purist, even it’s going to require a bit of extra planning from time to time. And again, for normal people with grid power, I don’t think many of these charger questions would even be an issue.

 Image credit: stefanphoto / 123RF Stock Photo