Guide to electric car recharging

With incentives to entice new car buyers towards electric cars, it’s clear that the Government is finally getting serious about electric vehicles. However, if we are to rush out and buy an electric car to capitalise on the incentives available how will we recharge it?

There are a number of concepts floating around relating to electric car charging points and the best way to create a large infrastructure for electric vehicles. So what are they and how will they work? This guide will investigate.

Quick links:

• How does electric car recharging work and what are the options?
• What is a battery swap station and how does it work?
• What is a high voltage recharging station and how does it work?
• What about charging from home?
• How safe is electric car recharging?

How does electric car recharging work and what are the options?

Electric cars use rechargeable batteries – originally these were NiCd batteries or nickel-hydride batteries but more recently they have progressed to lithium-ion and lithium-polymer batteries that offer more extensive range.

The batteries must be periodically charged and this is generally done by taking electricity from the power grid. Charging times are limited by the capacity of the grid connection and can range from a matter of minutes to achieve charges of around 80 per cent, to upwards of eight hours for a full recharge.

Most people do not necessarily require fast charging because they have plenty of time between using vehicles. For example, they may plug in their vehicle overnight to ensure it is ready for use the next day. However, as the use of electric cars expands it will be increasingly necessary to be able to charge the cars at regular intervals much as we refuel with petrol or diesel currently.

As a consequence several companies are devising recharging schemes and infrastructure for electric cars including:

- Battery swap stations
- High voltage recharging stations and charging points
- Charging from home

What is a battery swap station and how does it work?

Start-up companies such as Better Place have already begun installing battery swap stations in forward-thinking cities.

The battery swap stations have the appearance of a drive-in car wash and the idea is that when your car needs more energy you simply drive it into a station and its battery is replaced robotically with a battery that has a full charge. This system is already being used in some forms of industry to power electric forklifts.

The main benefit of battery swapping is speed – the whole procedure could take less than five minutes allowing electric car drivers to go about their lives much as they would if they were driving a petrol or diesel car. You can sit in your car while it takes place and you don’t have to recharge it yourself.

On the downside however, there are large costs associated with building these stations and there would need to be a suitable number of batteries in stock. There are also concerns over whether battery sizes and shapes will be standardised – Chrysler for example, is already using three different battery pack shapes.

What is a high voltage recharging station and how does it work?

Charging stations give drivers the convenience of charging their batteries while on the move and they are being installed at a quickening pace with London Mayor Boris Johnson having announced plans to install 25,000 charging points across the capital by 2015. Many companies are involved in this field including Elektromotive, Better Place and Coulomb Technologies.

Basically recharging stations offer you the chance to extend the range of your vehicle while you do something else – such as go to work, have a coffee or go shopping. Though there will a number of recharging stations established that offer other services while you wait, there will also be simple recharging points in car parks and at office buildings where drivers can recharge at their own convenience. Some of the fast charging stations can add around 30 miles of range in just 10 minutes.

The problem with charging stations however, is speed. It can take much longer to rejuvenate a battery than it does to fill up a car with diesel or petrol. There is also the issue of standardised connectors – without them, electric car drivers could be left to carry a number of adaptors around with them. Though fast charging could solve the problem of speed it is feared that quick recharges may stress the batteries and shorten their lifetime.

What about charging from home?

Charging at home seems like a natural and convenient method – you could plug in an electric car in the same way you plug in a mobile phone. It is convenient, the cost is cheap and future vehicle-to-grid technology may allow you to sell back some of your stored energy to the utility companies. This is also one of the most environmentally friendly methods for those that live an eco-lifestyle. If they create their own electricity from renewable resources they can become self sufficient.

However, charging from home is not convenient for everyone. For example, you may not have a house with a garage and it may be some time before charging points find their way into residential areas as they are only just emerging in cities.

Many drivers have raised concerns about the safety aspect of electric car charging. In particular there are concerns about the on-board storage of electricity and its propensity for fires, and the protection against electrical hazards.

Clearly dealing with electricity can be dangerous – just as it can whenever you plug in a standard appliance. However, many fire brigades have received extensive training in dealing with the high voltages and chemicals found in both hybrid and electric cars. In addition, recharging company Evoasis, which offers high voltage recharging, will have members of staff carry out the recharges so the public are never in danger.

Though there are concerns that accidents involving electric batteries would create unique problems due to their discharge there is no information currently that proves they are more or less dangerous than petrol or diesel which carry flammable fumes.

Paul Lucas, 2009