I read a Wired article earlier today that was suggesting the US needs to build out charging infrastructure rapidly to cope with the expected sales of new EVs, and especially in urban areas.
At Home Charging
Of course, for many of the current EV owners, at home is where they do most of their charging. The public charging infrastructure is useful for opportunistic top-ups, especially when free, but it is longer road trips where the rapid chargers are needed.
When EVs start to move from the suburbs into the cities, the options for overnight charging become harder. Maybe appartmemts and condos will install chargers for residents, but it’s hard to imagine that become one in every space, at least until we get to smarter charging infrastructure that can balance the load over time better.
Obviously, the thing most people will think of is the one that most closely resembles the way ICE vehcicles are refueled. Nobody has a gas (petrol) or diesel pump in their garage. We make a trip to a gas station to refill the tank.
With some of the very high speed chargers being talked about now, as well as the expected advances in battery technology in the next decade (which is the timeframe that a meaningful transition will take place in), this may well become a possibility for urban EV owners to charge their cars.
Slow & Steady
If any of those urban cars are being used for daily commutes, whether to an office, campus or even just a park & ride or station lot, it is likely they will sit there for more than eight hours. No need to plug them into a 350 kW rapid charger, or even a 50 kW one. Every 50 kW charger could provide slower, but still adequate, charging for several cars.
Assuming we need to get an 80% charge on, say, a 60 kWh battery, and allowing for a 20% charging efficiency loss, we end up needing about 60 kWh from the grid. Over 8 hours, that means around 7.5 kW charging rate. Which translates to almost 7 cars charging to 80% while parked all day for every 50 kW rapid charger.
Putting a slower, 7 kW charger on every space in a row is much more practical that installing many ultra rapids. Slower charging is also potentially nicer to the battery.
Gyms, Shops, Restaurants, Theatres, etc
These are the 1-4 hour duration locations. Not going to have time for an 80% charge using a 7 kW charger (although adding blocks of these would be a great start). The right answer will depend on the average length of stay., and also the distance to travel home. For example, a gym where most visitors are stopping on the way home from work might be fine with a few 50 kW rapids. Most people will arrive fully charged from the office lot and not need to charge. Those who do are only there for an hour or so, making the rapid a great choice.
Certainly it likely to be as common as the options above, but there really is no reason why some street parking spaces cannot be fitted with outlets capable of 7 kW charging. Most urban streets already have power for lights, so much of the infrastructure exists.
While I don’t disagree with the Wired article that we need more chargers, I do hope that we can start to educate people about the alternative models for refueling an EV. I fear much of the press is centered around the “how long does it take to charge” question, and for many people, even those in urban environments if they use their cars daily, that may be an irrelevant question. It is one of the questions I am always asked when people talk to me about my EV. Early on I would give them the answer, now I just say I don’t really know – I plug it in one or two nights a week and it is full by the morning when I need it.
I even reduced the charging speed on our home charger since I didn’t need it to charge at 7 kW the 3 kW rate was still fast enough that it is charged before I need it again.
Where we build out the charging network, and the types of chargers available is important. Let’s try not to replicate the “gas station” model with EVs – most of us have plenty of opportunity to charge while we do something else.