What’s Watt: Understanding the new language of EV charging
October 5 2021
Author : GRIDSERVE
If you’re new to the EV space or you’re thinking of making the switch, you may have noticed a lot of new language floating around. In this little guide, we’ll be decoding some of the terminology around EV charging so you can talk about it with confidence.
You’re finally ready to embrace a future of silent, smooth and, most importantly clean driving, but you’re a bit stumped when it comes to the specs. What does a 80kWh battery with 50kW charging actually mean? If you’re not totally sure, don’t panic, you’re not alone. We promise that you’ll soon discover that it’s much simpler than it sounds. Let’s break it down.
Firstly, what is a Kilowatt hour?
You’ll see that most electric cars on sale are marketed with a corresponding kWh figure. That’s because the size of an electric car’s battery is expressed in kWh, or kilowatt hours.
Range – how far the car can drive on a single charge – remains one of the most important considerations for EV drivers so, generally speaking, the bigger the kWh figure, the bigger the battery and the more electricity or ‘fuel’ you can store, which can imply a bigger range.
Take the hyped up Honda e, for example. It has a 35.5kWh battery and an official range of 136-miles, while the similarly sized Peugeot e-208 has a 50kWh battery and a range of 217-miles.
Of course, there are lots of other factors that can impact vehicle range. The weight of the vehicle, for example, whether you live near the Arctic Circle or are a distant relative of Lewis Hamilton.
Battery efficiency will factor all this in and sometimes be presented as miles per kWh. This is becoming the new standard for how electric cars measure energy economy although outside of the UK, EV electricity consumption is more commonly presented as kWh/100km.
OK, so what is a Kilowatt?
A Kilowatt (kW) is the most common measure of power created by an electric car’s motor or engine. It’s equivalent to about 1.34 horsepower (hp), and is used to measure the same thing: power, or energy transfer per unit of time.
It can also be used to describe how quickly a charging point can fill up your car’s battery. Power outputs of chargers can range from anything from 3.6kW at your conventional plug, all the way through to 350kW for our high power chargers at the Electric Forecourt®.
And because electricity flows like water, you can liken recharging your battery to filling a bathtub with water: using a domestic plug would be a bit like using a dripping tap, whereas using a high power charger is like bringing in a fire hydrant.
That said, just because a charger is capable of providing 350kW of juice, doesn’t mean your car is able to receive it. The Porsche Taycan Turbo boasts 270kW charging capability – the fastest charging capacity of any electric car on sale in the UK – which is still some way behind GRIDSERVE’s maximum capacity.
So, a kW refers to how much power you can charge your EV with, while kWh refers to how many actual hours of drive time your EV will give you from that power. And just so you know, GRIDSERVE uses pence per kWh as a standard metric to calculate how much your charge session will cost, so you’ll never have to pay more to access our high-power chargers.
What is the difference between DC and AC charging?
In the context of EVs, primarily speed. Power from the National Grid is always AC or ‘Alternating Current’, which has the flexibility to travel across high voltage power lines and then be transformed down to the 240V outlet you have in your home.
Electric cars can also accept AC charging. AC chargers generally offer up to 43kW because the car must convert AC into DC, or ‘Direct Current’, via a transformer before it is able to feed the battery.
There are no such restrictions with Direct Current, as everything from TVs to EVs run on Direct Current, so a DC charger that’s CCS, CHAdeMo or Tesla compatible, can offer bigger capacity and faster charging speeds.
What are the most common connector types?
CCS, CHAdeMo, and Tesla – these may look like random mash-ups of letters, but they describe the three main connector standards that are currently on the market to support rapid charging.
Generally speaking, CCS is the dominant connector type for most European vehicles, while CHAdeMo is favoured by some Japanese brands. Tesla benefits from its own proprietary network, although the latest models are also able to use a CCS connector.
What are charging curves?
When EVs charge, the power and speed will typically increase to a steady rate then taper down again to protect the battery when it’s almost full, hence the phrase charging curve. Let’s return to another bath analogy: in the interests of speed, you may want to start with a fire hydrant, but as the bath fills, you may wish to reduce the flow to avoid any spillage.
It’s the same with filling an electric car’s battery, and it’s why you’ll often hear about EV charging in terms of how long it takes to get from 20% to 80%. The rate of charge tends to slow down steeply after 80%.
What is regenerative braking?
Regenerative braking is a really nifty way that EVs use kinetic energy to charge their own batteries. Normally, when you hit the brakes and your car slows down, the friction results in some wasted energy, but a regenerative braking system allows some of that energy to be redirected to help charge the battery.
This is due to the design, which allows you to use the motor like a dynamo and put some juice back in when you lift your foot off the accelerator and onto the brake pedal. This also means that EVs often decelerate very effectively and have longer-lasting brakes, as their use is minimal.=
What does WLTP stand for?
Here’s another mashup of letters, and this one stands for ‘Worldwide Light Vehicle Test Procedure’. It refers to a method of testing electric, hybrid, petrol, and diesel cars for energy consumption as well as CO2 emissions.
The main benefit of the test for EV drivers is that it allows for a fair comparison of cars in terms of their range. It provides a realistic, standardised figure because the testing process is carried out both in a lab environment, as well as on the open road. This is important because driving behaviours, weather, terrain, and traffic can have a huge impact on the way cars use energy.
What does Slow, Fast, Rapid, and High Power Charging mean?
As the name suggests, this is the lowest power charging option you can initiate, and it will take around 20 hours to charge your EV to full. These UK domestic 3-pin 13 Amp sockets can be accessed from the outlets already in your home or garage, and are the same ones you use for charging any household appliance.
Fast chargers as they were once know are generally AC and provide between 7kW and 22kW of power, which will typically charge an EV in around three to four hours. The 7kW untethered charge point is now the industry standard in the UK, and these can usually be found at home, work, public charge points, supermarkets or leisure centres.
The term ‘untethered’ means that you’ll have to use your own cable. These are usually supplied when you purchase an EV, so check the boot for yours.
Rapid chargers offer up to 50kW DC power, and depending on your EV, you should be able to reach 80% battery capacity in 30-60 minutes on a rapid charger.
DC rapid chargers will always be tethered, which means that the cable you use is permanently connected to the charger in the same way a fuel hose is connected to a petrol pump.
High Power Charging
Also referred to as ultra-rapid chargers, these are the same as the rapid chargers above, however they offer another level of power. They provide between 90kW to 350kW of power, which means you can potentially charge your EV to full in 20 – 40 minutes.
We love helping EV drivers take charge
Hopefully, we’ve armed you with enough information on the language of EV charging, but if anything has gone unanswered or you need assistance, you can contact a member of the GRIDSERVE customer engagement team on our 24-hour helpline at +44 (0) 333 1234 333.
And if you’re in the market for a new EV, you might want to take a look at all the makes and models we have on offer here.
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