HGV are usually charged by being plugged in directly to the electricity grid. Charging is then provided by either alternating current (AC) or direct current (DC).

• In AC charging the vehicle has power electronics onboard to convert AC from the grid to DC to charge the onboard battery. This is used for slow and fast charging only.

• In DC charging the chargepoint contains the power electronics which converts AC to DC ready for the vehicle battery. This is used for higher power rapid and ultra-rapid charging.

Charging at the depot will typically be done via fast charging which, despite the name, is a relatively slow rate of charge when considering HGVs’ battery capacities. HGVs which are double or triple shifted and therefore do not have a long period of downtime when depot charging can be used and will rely exclusively on charging at higher rates of power.

Common terms for charging speeds are:

• Standard or slow charging (up to 7kW). This is commonly used for light duty vehicles; it would not normally be used for HGVs with large battery capacities.

• Fast charging (22kW). This is supplied by Mode 2 AC charging, using an on-board charger to convert the AC supply to DC. This is best suited to charging a vehicle where it is stationary for several hours, such as at a depot or overnight rest stop.

• Rapid charging (50kW). This is supplied by Mode 4 DC charging. Currently this is typically available at motorway service stations for charging light duty vehicles. It can also be used at depots for vehicles with a short time between shifts, or where space constraints mean one charger must serve multiple vehicles.

• Ultra-rapid charging (over 50kW). Typical speeds for ultra-rapid charging are 150kW and 350 kW. These rates of charging allow vehicles to quickly recharge while minimising downtime.

The Mode term mentioned in the charging speed explanation above refers to the interface and protection standards for electric vehicle charging equipment.

• Mode 1: slow charging from a regular electrical socket (single- or three-phase AC)

• Mode 2: slow charging from a regular AC socket but with some EV specific protection arrangement (i.e. the Park & Charge or the PARVE systems)

• Mode 3: slow or fast AC charging using a specific EV multi-pin socket with control and protection functions (i.e. SAE J1772 and IEC 62196-2)

• Mode 4: DC fast charging using a specific charging interface (i.e. IEC 62196-3, such as CHAdeMO)

Hardware and installation costs increase with speed of charging, so it is important to match the appropriate chargepoint power for each vehicle and application.

There are four types of chargepoint connectors to be aware of:

• Five pin Type 1. A charging standard commonly found in Asian and American markets, rather than in Europe.

• Seven pin Type 2. The main UK charging standard for slow and fast charging.

• CHAdeMo. A DC rapid charging standard favoured by Japanese manufacturers. It has historically been used in the UK but is gradually being replaced by CCS.

• Combo 2 CCS. CCS is the most dominant DC rapid charging standard in the UK and Europe and is expected to be the dominant standard use for larger vehicles.

The charging parameters and types of chargepoint are summarised in the table and graphic below.

Chargepoints can offer one or both AC and DC electricity supply delivered over one of four common connector standards.

Electric HGVs will primarily be charged at their depot, supported by charging during shifts as required. The key considerations are:

• Electric HGVs typically have large battery capacities and cover high mileages. Therefore depot charging would often be supplemented by charging during shifts (known as opportunity charging) at high rates of power.

• For short haul operations, electric HGVs may be able to complete their duty cycle on a single charge, provided overnight at the depot.

• Depot-based charging is more convenient and cost-effective than using a public network. This will be the preferred location for charging, where permitted by space and electricity network capacity.

Where depot-based charging is not possible or not sufficient, electric HGVs will need access to a public network of chargepoints. However, there are few sites currently available which are suitable for larger vehicles. Chargepoints installed for light duty vehicles will often not be suitable due to site access and bay size not accommodating HGVs, the risk of a larger vehicle blocking more than one chargepoint, and cables not being sufficiently long.