Isabellenhütte Introduces IEM‑DCC: A Calibrated DC Meter for Accurate Fast‑Charging Billing

Electric vehicle drivers will soon benefit from IEM‑DCC, Isabellenhütte’s cutting‑edge direct‑current meter designed for fast‑charging stations. The module allows charging to be billed precisely per kilowatt‑hour.

In compliance with German calibration law, which mandates DC measurement devices for EV fast chargers from April 1 2019, the partnership between Isabellenhütte—a leader in shunt‑based current and voltage measurement—and innogy, a top German energy firm and electromobility infrastructure specialist, produced the first compliant module. Until now, fast‑charging stations could only offer a flat fee, while AC stations already enabled kWh‑billing.

The IEM‑DCC, currently undergoing type testing by the Physikalisch‑Technische Bundesanstalt (PTB), meets the legal requirement and incorporates Isabellenhütte’s high‑accuracy shunt sensor. It integrates innogy’s patented kWh‑billing system, used at AC stations since 2014, into a compact, tamper‑proof housing that is smaller than a standard household meter.

The design supports up to 500 A of current and 1 000 V of voltage measurement, along with a four‑wire configuration for compensating cable losses—all within a small footprint. To secure data integrity, the meter uses innogy’s EDL 40++ protocol, which digitally signs measurements and synchronizes timestamps, ensuring tamper‑resistant communication at publicly accessible charging points.

Type‑examination certification is expected in the first half of 2019. Module‑F‑tested units will enter series production in Q3, ready for deployment in fast‑charging networks.