What is meant by the capacity of a car battery?
The capacity of a car battery is equivalent to the amount of energy that can be stored in it. It is measured in kilowatt hours (kWh) and is much like the size of a fuel tank on a conventional petrol or diesel-powered vehicle: the higher the capacity of your car battery, the longer you can run your car from a full charge before it stops, so higher-capacity batteries allow longer-distance travel between charges.
What is meant by the speed of a car charger?
The rated speed of a car charger tells you how fast your car battery can be charged using it. This is much like knowing the speed at which a petrol pump is able to pump petrol into a conventional fuel tank. Car charger speed is measured in kW, and can be used together with the known capacity of your battery to calculate the amount of time it will take to completely charge it. For example, a 95kWh battery would take just under two hours to fully charge using a 50kW charger, 14 hours using a 7kW charger, or 40 hours using a 2.4kW charger.
- Benefits of Electric Vehicle Use
- AC vs DC Car Chargers
- How Fast are Electric Vehicle Chargers?
- What Connectors do I need to charge my Electric Vehicle?
- Where Can I Charge My Car?
- What Electric Vehicle Chargers Does Gregor Supply?
Read on for a detailed overview of the different technologies for charging your electric vehicle.
There are several key benefits of using an electric vehicle over a conventional diesel or petrol-powered one. These include:
- Reduced impact on global warming – the combustion of petrol and diesel generates a significant amount of carbon dioxide, contributing to the anthropogenic greenhouse effect that is recognised by scientists as being the cause of the current trend to global warming. The powering of electric vehicles from renewable energy sources does not contribute any carbon dioxide to the atmosphere.
- Lesser pollution of local environment – both petrol and diesel exhaust introduce toxins into urban and rural air, putting at increased risk the health of drivers, passengers, cyclists, pedestrians and local residents
- Reduced risk to marine environment – petrol and diesel are products of crude oil, which is transported around the world on large tankers. Major oil spillages are an occasional occurrence, and can cause devastating effects to fish and other sea life
- Sustainability of energy sources – there is a finite supply of oil, and extracting it from the ground for use to power vehicles for energy use is not sustainable in the long run; the development of sustainable energy sources is supported by the choice of electric vehicles
- Government grants – when you purchase a qualifying new electric car or van, a grant is available from the UK government of up to £3500 or 35% (whichever is less) of the purchase price for cars, £8000 or 20% (whichever is less) of the purchase price for small company vans, and £20000 or 20% (whichever is less) of the purchase price for up to 200 large vans or trucks. See also the government’s Office for Low-Emission Vehicles.
- Reduced total cost of vehicle ownership – when you charge your vehicle at home, you will save a lot of money on its running costs compared with filling it up with petrol or diesel, especially if you charge from renewable energy sources in your home. Not only this but you will also save on the costs of maintenance associated with the parts of the vehicle because electric transmission systems are simpler and less subject to wear and degradation than internal combustion engines. So even though the initial purchase cost of electric vehicles is higher than those of petrol and diesel-powered vehicles, they tend to be a cost-saving investment in the medium- and long-term.
- Quieter, more comfortable ride – because electric transmission systems are quieter by their nature and less prone to vibration than those associated with combustion engines, you will tend to find that you and your passengers enjoy a quieter and more comfortable ride in a well-engineered electric vehicle than in one run on petrol or diesel
- Increased ease of driving – because electric transmission systems do not require manual gear changes and require less braking than combustion engine-based systems, you will tend to find that driving electric vehicles is easier and therefore less tiring
- Improved safety – since electric vehicles do not involve the burning of flammable fuel, there is a much reduced risk of them bursting into flames in the event of a serious accident, increasing the safety of both drivers and passengers
- Improved road-holding – electric vehicles tend to have a very low centre of gravity as a result of the weight of the battery being concentrated in the base of the car. As a result, they handle corners more easily, making for a more comfortable and safer driving experience
All electric cars are supplied with built-in AC chargers. AC (Alternating Current) is the standard technology used for mains electricity supplies in the UK. Almost all newer electric vehicles also allow DC (Direct Current) charging via special connectors which bypass the AC chargers.
The speed of electric vehicle charging depends on the type of charger and its built-in limits.
Electric car chargers run from a home mains supply generally run on one of two modes, called SLOW and FAST.
- SLOW mode is limited to 3.68 kW of power drawn from the mains.
- In SLOW mode, a typical small electric hatchback car with a 40kWh battery will take about eleven hours to charge.
- In FAST mode, the charger will draw as much as possible of the maximum 7.4kW of power from the UK mains
- So the same 40kWh car battery should be fully charged in about six hours provided that the built-in AC charger has been designed to cope with this rate of power.
Please note however that many AC chargers on smaller and older electric vehicles are limited to slower rates of charging than the UK mains theoretically allows.
- 3.7kW is a common limit.
- Some cars are instead limited to 2.8kW, 3.3kW, 4.6kW or 6.6kW.
You can see from this spread of maximum charging speeds that not all electric vehicles are compatible with FAST mode, and a few are even slower than the usual limit for SLOW mode. The slower the built-in charger, the longer it will take even in FAST mode to recharge your car from the UK main electricity supply.
When you instead connect your car to a dedicated public charger running at a much higher power output, this is called RAPID charging.
- The power output of RAPID chargers itself varies widely, but is most commonly in the range of around 22kW to 50kW
- 43kW is typical for AC models
- 50kW (or higher) is the norm for DC models.
- A car with a 40kWh battery will take only an hour to charge from a 43kW RAPID charger.
- Chargers faster than 50kW are always DC-based.
- Chargers with a power output of 100kW or more are collectively known as Ultra-Rapid chargers.
To get the full speed of RAPID and Ultra-Rapid chargers, you will need to bypass the built-in AC charger in your car. On recent models of electric vehicles, battery capacities have increased to satisfy the demand for longer range between charges. As a result, RAPID charging is increasingly important.
- For example, the Nissan Leaf E+ has a 62kWh battery
- The battery for the Tesla Model S Long Range and Model X Long Range is rated at 95 kWh.
- The Nissan’s 62kwH battery is estimated by its manufacturer as taking 11 hours and 30 minutes to fully charge on FAST mode – just enough time for a full overnight recharge!
- However, the 95kwH Tesla Long Range batteries would take more than 14 hours to charge on FAST mode even if the supply of 7kW of power was continuous and the charging process 100% efficient.
While charging times of over 14 hours might be viable at weekends for a regular commuter, the availability of RAPID public charging points to top up high-capacity batteries more quickly is understandably attractive!
- Tesla’s own dedicated public charging points, called Superchargers, are ultra-rapid, and much faster than standard RAPID chargers
- Second-generation Tesla superchargers have power outputs of up to 150 kW, enough to fully charge a 95kWh battery in about 40 minutes.
The type of connector you need for charging your vehicle will depend on whether it takes a Type 1 or Type 2 connector.
- Type 1 connectors are most common for models of car produced in Asian countries and are rarely found in cars produced in Europe, which usually take Type 2 connectors.
- The Type 1 connector is a single-phase plug allowing for charging up to 7.4kW.
- The more commonly found Type 2 connector is a triple-phase plug and is compatible with power charging levels of up to 43kW.
- Public charging stations for RAPID charging in the UK and the rest of Europe typically use so-called Mennekes plugs, which are designed for Type 2 sockets.
- A CCS plug is a modified version of the Type 2 plug, and supports much higher rates of charging (including DC as well as AC), theoretically up to 170kW, though more commonly 50kW, and is likely to be needed for public Ultra-Rapid charging stations.
- Tesla supplies its own modified type 2 Mennekes plug (different from the standard CCS plug) for use with its Superchargers.
- The Chademo connector is a DC connector that is popular for Japanese cars and allows charging up to 50kW. It is compatible with electric cars produced by a wide variety of manufacturers including Citroën, Honda, Kia, Mazda, Mitsubishi, Nissan, Peugeot, Subaru and Toyota, and also older models of Tesla.
If you are charging from home, you will also need to think about the connection at the power supply end!
- For SLOW home charging, all that is needed at the domestic end of the connection is a standard AC mains connection with a 3-pin UK plug.
- For FAST home charging, it is recommended to install a single-phase power supply for use in connection with a specialised electric vehicle charger.
Our Renewable Energy team can help guide you with all aspects of supply and installation!
You can plan longer trips judiciously with reference to the location of suitable rapid chargers, or find a public charging point near you, using the interactive third-party resource provided at Zap Map. Currently available chargers are outlined in black on the map. The charging points are also colour-coded by speed, with the pink markers showing rapid charging stations and the more common blue chargers fast stations. Some slow chargers are also available for public use, and these are shown in yellow.
At Gregor Heating, we supply and install specialised chargers by Zappi, ROLEC and Solar Edge. For further information, please see our dedicated page Home Electric Vehicle Chargers. For all enquiries relating to electric vehicle charging connectors and power supply installations, call Gregor today on 0117 935 2400 and ask to speak to our Renewables team.