Everything I've Learnt About Public EV Charging With Two Failed Startups

decryption · 29 August 2022 12:53

EV Charging Basics

Here’s a crash course in electrical basics:

All batteries use and output direct current (DC) electricity.
Electricity from the power grid is alternating current (AC).
To change AC into DC you use a rectifier.
To change DC into AC you use an inverter.
To increase or reduce voltage you use a transformer.
Single phase electricity is 230V-240V, three phase electricity is 400V-415V.
Three phase electricity can be split into three single phases (e.g: 63A 3p = 183A 1p)
Power (watts) is equal to the voltage (V) multiplied by the current (A).

Actual engineers or electricians are probably cringing, but like I said, it’s a crash course! Knowing this stuff now will help make sense of the rest of this post. Schneider have an excellent wiki explaining everything related to the electrical side of EV charging and other electrical basics. I strongly suggest reading at least the EV section.

AC & DC charging

EV chargers (or EVSE, electric vehicle supply equipment if you want to get fancy) come in two basic types - AC and DC units.

AC Chargers

AC units are relatively basic and can be viewed more or less as a fancy switch.
There’s a rectifier inside the car that turns the AC power into DC power for the battery.
The maximum power an AC charger can output is 22kW compared to 350kW+ for a DC charger
Maximum AC power a car can handle depends on the rectifier in the vehicle (more on that later), typically 7kW, 11kW or 22kW.
AC units are much cheaper than DC chargers ($500 - $7500)
Can be purchased from most electrical wholesalers.
Easy for most electricians to install, not much different to an air conditioner or hot water system.
Sometimes there’s a cable attached, sometimes you bring your own cable (~$300 for a cable).
AC chargers are sometimes called “destination chargers” as they are commonly installed at your destination.

This video does a good job of explaining how an AC charger works:

Here’s some common AC chargers in the wild:

A couple of Schneider units in Armstrong Creek. By far the most common AC units I’ve seen. These have two sockets on em and can be maxed out at 22kW per socket. BYO cable required. I don’t know how this particular site is wired up, but it could be as simple as a single 32A 3-phase circuit that all three chargers share. They can be configured to share the load so if one car is charging, it gets the full 32A. If a second car comes, each gets 16A. If a 3rd arrives 10A each and so on.

These are also Schneider units, but wall mount instead of floor mounted. Bit easier to install.

A Tesla destination charger at Docklands I think. It’s got a cable already, no need to BYO. Sometimes these are configured to work with non-Teslas, sometimes they are not. Up to the place that installed them to flick a switch in the unit (or log-in to the unit’s control interface and tick the box) to decide.

Jetcharge, probably the largest EV charger installation business in the country, has started making their own EV chargers. Dunno why they didn’t like the other products on the market, but whatever. They’re becoming more and more popular just due to the fact they’re the biggest in the country and they recommend their own unit over others.

DC Chargers

DC chargers are giant rectifiers. They take the AC power from the grid and change it to DC power for the car’s battery.
Because they bypass the car’s built-in rectifier they can supply much more power and charge the battery faster.
How fast they charge depends on the car and the battery (more on that later).
Much more expensive to purchase due to the complexities of rectifiers.
Much more expensive to install due to the huge amount of power they can support, often grid upgrades are required for chargers above 120kW.
25kW (~$12,000) to 350kW (~$150,000) available, various prices, models and suppliers.
Very heavy, can’t be mounted on a wall, need to be bolted into ground.
Cable always supplied, sometimes cable is watercooled.
Sometimes the rectifiers and the charging “head” are split, sometimes they’re all in the one box.
Not usually purchased off the shelf and need to be custom ordered. Can take weeks to months for stock to arrive.

Here’s photos of some common DC chargers you’ll see in Australia:

This is a Chargefox site in Ballarat. On the right are 2x 50kW units. On the left are 2x “350kW” units. On the right of that is a transformer (the smaller box against the wall) that takes the high voltage power direct from the transmission lines/substation and turns it into 400V/800V. That’s connected to the switchboard on the right. That box with the sign on it are the rectifiers (connected to the switchboard) for the 350kW units. The chargers are wired directly to that box via DC cabling. The 50kW units have their own built-in rectifiers.

Here’s an Evie site in Ascot Vale. There’s two Tritium chargers here that have their own built-in rectifiers. I think they’re configured for 70kW each, but can be upgraded by adding additional rectifier modules like the chargers above in Ballarat. That big grey box with 4 doors on it near the power pole is the switchboard and meter for the two chargers. There’s no need for a transformer as these chargers are not as powerful as the ones in Ballarat and the supply feed is already at the 400-415V these chargers need.

This is a Delta 25kW unit in Cobblebank. See how much smaller it is? Even though it hasn’t got much more power than a 22kW AC unit, because it’s a DC charger it can bypass the built-in rectifier in the car and charge at 25kW instead of 11kW or 7kW over AC power. Because it’s small it can also be mounted on a wall if you want to save on install costs.

Tesla Superchargers in Colac. I can’t see a transformer (this shopping centre probably has a chunky supply feed already), but you can see the switchboard and a rectifier behind it that the Supercharger “heads” are connected to via DC cabling. Like the Tritiums in Ballarat, the rectifiers are shared between all the charging heads rather than each one having their own like the units in Ascot Vale.

EV Plug Types

In Australia we use Type 2 for AC charging (sometimes called Mennekes, or IEC 62196-2) and CCS2 for DC charging. They’re also the same in Europe. They look like this:

America, South Korea & Japan use Type 1 for AC (also called J1772) and CCS1 (USA) or CHAdeMO (Japan) for DC charging. They look like this:

AC Type 1/J1772 plug

DC CCS1 plug

DC CHAdeMO plug

In the USA Tesla has its own proprietary plug that’s not Type 1 or CCS. Irrelevant for us, but if you talk with Americans they’ll bring this up.
In Europe the Tesla chargers are the same as ours and you can even charge a non-Tesla at a Tesla charger! That’ll probably happen here one day.
In Australia you can only charge a Tesla at a Tesla Supercharger. Tesla cars can use other CCS2 chargers, but your non-Tesla can’t use a Supercharger. Rude isn’t it? But you can sometimes charge a non-Tesla at a Tesla branded “destination/AC” charger.
The Nissan LEAF, being a Japanese car, uses CHAdeMO, even though it’s sold in Australia.
There are adapters to go from Type 1 to Type 2 and vice-versa, but not for CCS to CHAdeMO.
There are a handful of Type 1 chargers will around from the very early days of EVs here, but they’re slowly getting replaced.
China uses the GB/T standard for their AC & DC plugs. Looks like Type 2, but the pins are in a different order.

How long does it take to charge an EV?

You’d think this is a simple question, but it depends on so many factors and is actually a pain for most people to work out.

AC or DC charging?
How full is the battery already?
If AC, what size rectifier is in the car?
If DC, how much power does the charger have and what condition is the battery in?

But to use the Tesla Model 3 Standard Range (the most common EV in Australia) as an example:

AC charging is capped at 11kW. If you’re plugged in to a 22kW charger it’ll charge at a max of 11kW. If plugged in to a 7kW charger, it’ll charge at 7kW. The power output won’t change throughout the charging session as this power level isn’t enough to impact the battery. The Model 3 SR+ uses 132Wh per kilometre, so if plugged in at 7kW for 90 minutes, you’ve added 10.5kW of power to the battery. That 10,500W will add 79km of range (10,500W divided by 132 Watt hours). The battery can hold up to 57.5kWh of power, so if you want to go from 10% to 100%, you’ll need roughly 52kWh of electricity. At 7kw, that’s 7.5 hours of charging.

Inside EVs has a solid article with details about DC charging. While it can top out at whopping 159kW, it depends on the battery’s state of charge. See this chart for how it declines the more full the battery is:

This chart shows how long it takes to fill the battery to different percentages:

Starting at 20% and want to get to 80%? That’s gonna be about 25-30 minutes.

Complicated, right?! This is just the Tesla Model 3 - a Hyundai Ioniq 5 or a BYD Atto 3 will be different due to how the battery pack and charging management system in the car is configured. I wish it was easier but that’s just the nature of how electricity and batteries work.

This diagram from Schneider uses an EV with a 40kWh battery (i.e: Nissan LEAF) as an example:

How much does it cost to charge an EV?

Depends where you charge it! Using a Tesla Model 3 Standard Range (13.2kWh/100km) this is how much you will pay to move 100km at the nearest chargers to my house.

Home from solar (5.2c/kW in lost FIT in VIC) - $0.69
Home from grid (23.33c/kW VIC default offer Powercor area) - $3.08
Stockland Ballarat (7kw AC charger) - free
Chargefox Ballarat (40c/kwh, 50kw DC charger) - $5.28
Chargefox Ballarat (60c/kwh, 350kw DC charger) - $7.92

As you can see, pricing varies based on location and type of charger. Personally I think 30-40c/kWh for AC charging and 60c/kWh+ for DC charging is fair. This infrastructure isn’t cheap. To compare, the same 100km with a Toyota Camry Hybrid (4.7L/100km) will set you back $9.40 for 4.7L of 95RON petrol @ $2/L, so even at 60c/kWh I’m saving money versus petrol.

How do drivers find chargers and plan routes?

Apple & Google Maps - not sure where they pull info from. I assume they scrape the popular apps and other databases with generous licences.
In-car navigation - typically provided by TomTom, you can submit charging stations to them!
Open Charge Map/Open Street Map - because the data can be freely used by anyone, many charger databases/apps/maps simply suck in data from these sources (like ABRP), so it’s a good idea to add your charger there too.
Tesla navigation - disappointingly only shows Tesla chargers, so a decent amount of Tesla owners don’t even know non-Tesla chargers exist!
PlugShare - by far the most comprehensive database of EV charging stations in Australia. I wrote an article about PlugShare and ABRP (an app to plan EV journeys).
Charging network provider apps - Evie & Chargefox have their own apps. I don’t use them to find chargers, but I’m sure some people do.