What to know about rapid and ultra-fast EV charging

What do charging speeds mean? And how does a higher-powered charge impact your battery?

At bp pulse, we’re growing our network of rapid and ultra-fast EV chargers to help you spend less time charging and more time enjoying the journey.

Read on to better understand how these more powerful chargers can affect charging times and battery life.

First, let’s talk about electricity

To understand rapid and ultra-fast charging, you’ll find it helpful to know about Direct Current (DC) and Alternating Current (AC) – the two ways electricity can flow. All EV batteries charge using DC – however, the electricity grid provides power in AC.

EVs typically have an in-built AC/DC converter to convert the charge of an AC EV charger - such as a home charger or the bp pulse 7kW charger. But this conversion can slow things down.

Want to know more about this? Read our handy guide.

So, what is rapid and ultra-fast EV charging?

Most rapid and ultra-fast EV chargers have built-in AC/DC converters to provide power in DC – and because this happens in the charger rather than the car, it can be more efficient.

You’ll have noticed these chargers also have a kilowatt (kW) rating from 49kW to 300kW, meaning they have the capacity to provide more power than 7kW chargers. More power, already converted to DC charge, can make speedier charging possible – depending on other factors, including your EV’s make and model, battery size, and state of charge (how full your battery is).

This is how we define our chargers (other charge suppliers may do it differently):

Rapid: Our ‘rapid’ range includes 49kW AC, 50kW DC and 75kW DC chargers

Ultra-fast: These bp pulse chargers deliver power up to 150kW or 300kW.

How much charge can your vehicle take?

The charging power your EV can get from a rapid or ultra-fast charger is determined by a few factors – not just the charger itself. The amount of charge an EV can take varies between different makes and models. Here are the main reasons why:

Battery capacity – all EV batteries have a maximum capacity, typically measured in kilowatt-hours (kWh). A higher kWh rating means the car battery can store more energy, which may mean it takes longer to fill. On the upside, larger batteries take longer to deplete, so you may be able to go further before you need to charge again.

Battery Management System – EV batteries generally aren’t designed to be charged repeatedly to 100% capacity. That’s why most EVs have a battery management system (BMS). To protect the lifespan of your battery, it manages the charge rate and slows it down when the battery reaches a certain charge level, usually 80-90%.

Maximum Charging Acceptance Rate – Your EV’s BMS and onboard charging system also define your EV’s maximum charging acceptance rate. So, if your car has a maximum charging acceptance rate of 100kWh, it won’t charge at a higher rate, regardless of whether the charger is able to deliver at a speed of 150kWh or more.

Cells and Chemistry – The way an EV battery has its cells ordered is known as cell structure, and the components it’s made from are known as its chemistry. Different types of EV batteries have different cell structures and chemistry, which can affect charging rates differently.

EV batteries and battery life

A few different factors also impact your EV’s battery life. The most significant ones are:

Weather – If the car is regularly exposed to cold weather, this can cause the battery to discharge more quickly, which means more frequent charge-ups.

Driving conditions a vehicle experiences – Some types of driving (like regularly being stuck in traffic) can be more demanding on an EV battery.

Battery capacity – You might also charge and discharge your battery more regularly if it's smaller – so choosing a car with a bigger battery can be good for overall battery life.

BMS efficiency – Your EV’s battery management system’s efficiency can mean some EVs protect their batteries more than others.

Does rapid and ultra-fast charging affect battery life?

From what we’ve taken you through, you can see several factors affect battery life. Reassuringly, a recent study found ‘No statistically significant difference in range degradation between fast charging more than 70% of the time and fast charging less than 30% of the time.

So now you know a bit more about them, make sure you can find one as quickly as possible. Download our free app to help you search for chargers on your route - and, with rapid and ultra-fast EV chargers available at locations including M&S, you can top up while you tick off your to-do list.