Project funded with a grant from UK Government’s Red Diesel Replacement Phase 2 Competition
Danfoss Scotland, part of Danfoss Power Solutions, has shared the results of its Dextreme Max system validation in a 30-tonne battery-electric excavator
Conducted with a £4.29 million grant from the UK government, Danfoss demonstrated that its Dextreme digital hydraulic architecture reduced excavator power consumption by 35% across a representative duty-cycle mix, corresponding to 53% longer runtime on a single charge. The results highlight the Dextreme Max system’s potential to improve energy efficiency and accelerate the electrification of large excavators.
Danfoss’ Dextreme Max system aims to reduce excavator energy consumption by up to 50% by limiting energy losses and recovering energy that would otherwise be wasted. The system’s integral component is the DDP1X0D, a Digital Displacement hydraulic pump/motor with multiple independently controlled outlets. The Dextreme Max system can provide independent actuator supply, estimate flow-sharing losses, and facilitate energy recovery from excavator motions.
In 2023, Danfoss received a grant from the Red Diesel Replacement Phase 2 Competition, a programme funded through the Department for Energy Security and Net Zero’s £1 billion Net Zero Innovation Portfolio, to develop and validate the Dextreme Max system. The program funded projects developing low-carbon alternatives to red diesel for the construction, mining, and quarrying sectors. With its funding, Danfoss procured a battery-electric excavator and integrated its Dextreme Max system into the machine. The grant covered 65% of the eligible costs, with Danfoss funding the remainder.
Danfoss chose a Develon DX300LC-7 crawler excavator for the project. Originally diesel-powered, the excavator was supplied in an electric configuration by Staad B.V., replacing the engine with an electric drivetrain consisting of a Danfoss Editron EM-PMI375 permanent magnet synchronous motor, EC-C1200 inverter, and MC050 motor controller, as well as three 140kWh batteries.
Danfoss engineers replaced the excavator's conventional swashplate hydraulic pump with the DDP180D pump/motor. The excavator’s four primary services: boom, arm, bucket, and swing, are supplied through ten individually controllable outlets on the pump. These outlets are grouped through a ganging block, a digital distributor that reallocates capacity to the service requiring it. A dedicated valve operating as a hydraulic H-bridge was developed and applied to the boom function, enabling independent metering to provide anti-cavitation, pressure amplification, and energy recovery during overrunning motions. The control system architecture was developed to provide real-time control of the hydraulic system, electric powertrain, and auxiliary subsystems.
Multiple tests were conducted to compare system performance before and after conversion, including JCMAS air grading and JCMAS air dig-and-dump. Compared to the baseline electric excavator, the Dextreme Max system reduced battery energy use by 49.2% for air grading and 31% for air dig-and-dump, with negligible impact on cycle time. Assuming a 30% grading duty cycle and 70% digging, Dextreme Max would reduce battery power consumption by 35% without significantly impacting work rate. This would lead to 53% longer operating hours with the same battery capacity as the baseline machine, or a runtime similar to the baseline with two battery packs instead of three.
Alasdair Robertson, senior director, Digital Displacement, Danfoss Power Solutions, said, “The results of this testing highlight the potential of digital hydraulic architectures to overcome the obstacles in heavy-duty machinery electrification. Electric excavators offer excellent responsiveness, smooth control, a quiet cab environment, and zero-emission operation. With Dextreme Max, they can also deliver the runtime, productivity, and total cost-of-ownership advantages required for wider adoption, thereby accelerating the decarbonization of heavy-duty machinery.
“We are extremely encouraged by these results, but there is more work to do. Further gains are possible, and we will continue optimising the system to maximise the energy savings and value for our customers.”
