Even the most STEM-challenged among us are familiar with the abbreviation km/h. It means kilometres per hour, usually in the context of vehicle speed. In the era of the electric vehicle (EV), however, km/h has acquired a whole new meaning: kilometres of driving range added for every hour of charging time.
While total driving range remains the overriding preoccupation of EV viability, charging speed runs it a close second. And as battery capacity continues to increase (the new Leaf Plus has 62 kWh, for example), the need for faster charging is growing in tandem.
To learn more about the ins and outs of charging, we paid a visit to Plug’n Drive, a non-profit in Toronto that promotes and educates about electric mobility. Here is what we learned.
Level 1 Chargers
If you have an electric car, Level 1 charging needs no further investment (except time). Every EV comes with a portable, on-board cable. You plug one end into the car’s charge port and the other end into a 120V outlet. On the plus side, there’s no upfront cost, and, in an away-from-base emergency, you can top up from any 120V outlet (with the owner’s permission, of course). The negative: It’s slow. Rule-of-thumb, you recoup about eight km of range for every hour of charging, according to Plug’n Drive. That’s fine for a daily commute of less than 60 km, but limiting otherwise.
Level 2 Chargers
These are the 240-volt charging stations that EV owners would install at home. Plug’n Drive lists 16 Level 2 charger models from six manufacturers, typically priced in the $800 to $1,000 range (more for high-output or remotely-programmable versions).
Most come in hard-wired or plug-in models, the latter making it easy to take with you if you move. Unless you already have a handy 240V oven/dryer outlet with the appropriate NEMA 6-50 or 14-50 socket, you should budget $500 to $1,000 for a qualified electrician to install the unit. Most chargers output 30 amps, although some go higher – appropriate breakers will be needed.
Connecting cables are usually fixed to the charger and typically at least six metres long. The current Nissan Leaf, however, has a portable cable that can be plugged directly into a suitable 240V NEMA 14-50R outlet installed by a qualified electrician.
A Level 2 charge rate is about 30 km of range an hour. Plug-in hybrids, incidentally, may not be equipped to take more than a Level 2 charger, but since a PHEV battery is much smaller than a full BEV, that shouldn’t be an issue.
Level 3 Chargers
Level 3 DC Fast Chargers are the EV’s equivalent of gas stations – that is, the public charging stations that are becoming ubiquitous. These units typically claim to replenish a battery to 80 per cent state of charge (SoC) in 30 to 45 minutes. Why just 80 per cent? Because charging rates are not linear: Above 80 per cent, the rate of charge slows dramatically. Even if you are prepared to wait, the next user may not be. Besides, you’ll likely be charged a penalty for overstaying.
Level 3s are typically 400V and up, but their outputs are expressed in kilowatts (kW). The baseline on most DC fast chargers in Canada is about 50 kW, but new and future installations will offer 100, 150 or even 350 kW charging
That said, charge rate is limited by what your EV can handle; there may be no benefit in using a 150-kW charger if your EV’s on-board hardware can’t take all the extra power. That doesn’t mean you can’t use higher-output charging stations; the vehicle and the charger will automatically sort it out among themselves how much to deliver.
DC Fast Chargers are more efficient for the car because the charging current can go straight to the battery, whereas the household Levels 1 and 2 have to be converted from AC in the car, with consequent energy losses. However, the DC Fast Chargers put more strain on the battery and hence long-term battery life may be reduced.
Tesla established its own proprietary network of Superchargers with connectors exclusive to Teslas. The company claims its chargers are the world’s fastest, with up to 150 kW (although rival systems are catching up); depending on the battery, it claims 240 to 270 km of range added for every 30 minutes of charging time. Historically, it wasn’t possible to charge a Tesla on CHAdeMO or CCS systems, nor could other brands be charged on the Tesla chargers. But that appears to be changing: Newer Teslas come with a CCS adapter and it may be possible to retrofit older ones. As well, aftermarket adapters enable non-Teslas to use Tesla’s Level 2 Destination chargers.
There are basically two charging systems, each with their own unique plugs: CHAdeMO used primarily by Asian manufacturers; and J1772 used primarily by the North American and European companies. However, CHAdeMO (originally developed in Japan) appears to be on the way out. Indeed, newer EVs from the South Korean and some Japanese manufacturers are J1772.
Then there’s CCS, which is a J1772 plug with two additional pins as found on DC Fast Chargers; your J1772 EV will already have a socket that can accept the CCS plug’s extra pins (which are bypassed by the plug on a Level 1 or Level 2 home charger). Some Asian vehicles have two separate sockets – CHAdeMO for public fast charging and a plain J1772 for Level 2. Likewise, many Level 3 public chargers have two connectors, one of each type.
Paying for it
Some public charging stations are free, provided as a service to their customers by businesses or malls. Most, however, require payment, and are more expensive than off-peak charging at home. Payment may be by credit card or, if you’re signed up with the network, by RFID (radio-frequency identification) card. Some networks charge a flat rate (for example, $15 to $20) while others charge by the minute.
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