Certified DC meter solution for EV chargers

Offering a power measurement range from 25 to 600kW, the DCBM is a legal and certified meter that provides accurate billing of DC chargers.

With around 2.5 million plug-in electric cars in 2019, charging infrastructure is set to play a major role in worldwide mobility. Today’s public charging infrastructure supplies mostly alternating current (AC). This leads to a relatively long charging time of eight hours on average, due to a low power capability of around 44 kW.

To reduce this charging time to only a few minutes, charger manufacturers convert the AC into a direct current (DC) outside the car, bypassing the On-Board-Charger (OBC) and supplying the battery pack of the electric vehicle directly. This method can boost charging power up to 400 kilowatts. However, this conversion stage generates power losses, which do not have to be paid for by the end user, the EV’s owner. Thus, an electric meter is placed after the conversion stage to monitor and bill the exact energy transferred to the electric vehicle.

The German ‘Eichrecht’ regulations state that consumers should only be charged for the DC power supplied. Standards are being established not only at the European level but also at the international level and more particularly in the USA in the state of California.

The DCBM has been developed to meet market demands for inter-operability and data security, easy and fast retrofitting of charging stations already deployed, and the ability to provide high power at up to 600A/1000V. Designed to meet future connectivity needs, the DCBM offers Ethernet communications, supporting the HTTPS/REST protocol to allow quick integration and deployment within charging stations.

The DCBM also integrates the Signed billing data sets according to the S.A.F.E OCMF protocol, allowing billing data to be transmitted with an extremely high level of security and providing total interoperability for cloud service operators.

The DCBM project is already a success due to an exceptional cooperation between LEM customers, standards committees, laboratory institutes, and the global teams of LEM. The DCBM has been designed in record time by the LEM R&D centre in Lyon, France, and by the Industry-segment team in Geneva.

Technical benefits:

• Standardised Direct Current Billing Meter in compliance with VDE-AR-E-2418-3-100.
• Adjusts meter accuracy according to the charging cable in use.
• LCD display shows live measurements, energy, alarms and legal data.
• Ethernet communication allows quick integration and deployment into charging stations.
• Signed billing data sets offer extremely high security and total interoperability for cloud service operators.