Digital Hydraulics Increase Electric-excavator Runtime

March 3, 2026

Matteo Pellegri, Danfoss Power Solutions

Danfoss engineers replaced the original 140-cc/rev swashplate tandem pump with a 180-cc/rev Digital Displacement tandem pump/motor – the DD180D (shown) – and a ganging block. (Danfoss)

Machine runtime and cost remain the primary barriers to electric machinery adoption, particularly heavy-duty machinery such as large excavators. To avoid downtime, batteries must be sized to last a full shift. This drives up costs, as battery packs are the single most expensive component of a battery-electric machine.

At the same time, excavators are among the most energy‑intensive machines on a jobsite. Any avoidable inefficiency becomes a direct burden on the battery, shortening runtime and increasing the number of charges required per day.

However, electric machines offer significant advantages. They deliver better breakout power, superior responsiveness and smooth control. They eliminate engine noise, creating a quieter cab that improves operator comfort and communication on site. And with no exhaust emissions, they help contractors win projects on sensitive or urban jobsites. Electric excavators are attractive; the challenge is making them practical.

The acquired excavator is shown being converted to the digital hydraulics system at the Danfoss Application Development Center in Nordborg, Denmark. (Danfoss)

Hydraulic inefficiency

Even with a highly efficient electric drivetrain, excavators inherit a major energy challenge from their diesel counterparts. Conventional hydraulic systems waste up to 70% of the useful power delivered by the prime mover. This inefficiency stems from several distinct loss mechanisms throughout the system. Flow-sharing valves introduce meter-in losses when reconciling differential load pressures across actuators, while meter-out losses are necessary for controlling overrunning conditions. Compounding this, pumps rarely operate at their optimal displacement and pressure point during real duty cycles, driving further inefficiency.

A fully digital, multi-service electrohydraulic architecture has the potential to mitigate these losses, significantly improving system efficiency. This would reduce required battery capacity, thereby decreasing total cost of ownership through lower upfront and charging costs. It could be the impetus needed to accelerate electrification.

Hydraulic system schematics of the baseline excavator and the converted excavator. (Danfoss)

An investment in decarbonization

Recognizing the importance of electrification in off-highway machinery decarbonization – and thus the need for hydraulic innovation – the UK Government awarded Danfoss Scotland a £4.9 million grant in 2023 through the Red Diesel Replacement Phase 2 Competition, part of the Department for Energy Security & Net Zero’s innovation portfolio. The funding enabled Danfoss to validate its digital hydraulic architecture, Dextreme Max, in a 30‑tonne electric excavator.

The Dextreme Max system is designed to cut excavator energy consumption by reducing energy losses and recovering energy that would otherwise be wasted, such as from boom lowering. At the core of the Dextreme Max system is a Digital Displacement pump/motor with multiple independently controlled outlets. The system provides independent actuator supply, eliminates flow-sharing losses and enables energy recovery.

Electric excavator conversion

Danfoss selected a Develon DX300LC-7 crawler excavator for the project. Originally diesel-powered, it was supplied in an electric configuration by Staad B.V., which replaced the engine with an electric drivetrain and three 140-kWh batteries, two of which are swappable to meet uptime demands.

Danfoss engineers replaced the original 140-cc/rev swashplate tandem pump with a 180-cc/rev Digital Displacement tandem pump/motor (the DD180D) and a ganging block. The pump independently supplies the excavator’s four primary services – boom, arm, bucket and swing – through 10 controllable outlets. These outlets are dynamically grouped via the ganging block, a digital distributor that reallocates capacity to the actuator requiring it.

Matteo Pellegri, senior engineering manager - digital displacement systems technology, Danfoss Power Solutions. (Danfoss)

Full decoupling of the four services was not implemented due to project time constraints and the need to retain the main control valve (MCV) without altering its core functions. Energy-flow analysis demonstrated that retaining the MCV for the arm and bucket circuits introduced acceptable losses.

Previous studies have shown that boom and swing functions are the main candidates for energy recovery, as they dominate potential and kinetic energy exchange during excavator cycles. The boom typically offers several times higher recovery potential than other actuators and about two to four times that of the swing. As a result, both functions received dedicated valve services.

Because the DD180D is an open-circuit pump/motor, additional valve functionality is required for full bidirectional control of the linear actuators. The project team developed a dedicated H-bridge valve and applied it to the boom function to manage independent metering, providing anti-cavitation, pressure amplification and energy recovery during overrunning motions. Due to the challenges presented by the open-circuit system and the project timeframe, practical energy recovery on the swing function could not be implemented. The swing function used an independent metering valve to remove flow-sharing and metering losses.

The introduction of four independent services required a complete redesign of the control strategy. The controller must manage flow allocation, displacement distribution, pressure regulation, torque sharing and boom-specific recovery logic, while ensuring seamless operator control and compatibility with the machine’s electric prime mover.

The control system architecture was designed to provide real-time control of the hydraulic system, electric powertrain and auxiliary subsystems. The main controller executes the system’s supervisory control, coordination of subsystems, advanced algorithms such as motoring and digital distribution, power limiting and fault handling. Two other controllers act as distributed I/O nodes that interface directly with the hydraulic valves, pilot signals and pressure sensors. These units also serve as functional safety controllers, implementing local safety logic and redundancy for critical valve operations.

The final step of the conversion was to outfit the excavator with a comprehensive data acquisition system consisting of hydraulic pressure sensors, flow meters, position sensors and an electrical power sensor. The measurement system enabled synchronized high-speed recording across all channels, including hydraulic, mechanical and electrical domains, allowing a detailed analysis of machine performance, energy flow and control behavior.

Test setup and results

To compare system performance before and after conversion, a series of tests were carried out, including JCMAS air grading and JCMAS air dig and dump (equivalent of ISO/AWI TS 11152-2). These tests were selected as they offer a controlled and repeatable means of assessing system efficiency.

Since the DD180D pump’s displacement is 30% larger than the baseline pump, the converted excavator operates faster than the baseline unit. To align cycle durations, motor speed setpoints were adjusted for the converted machine tests, with active control of the electric motor speed during boom down to maximize energy recovery.

Machine operators conducted several tests, each consisting of 10 cycles, for both air grading and air dig and dump. The operators were instructed to keep the trajectories consistent while working as quickly as possible. To ensure a fair comparison, a bucket-tracking tool was used to verify motion repeatability, and outlier cycles were excluded from the energy analysis.

In comparison to the baseline electric excavator, the converted machine with the Dextreme digital hydraulic architecture reduced DC energy use by 49.2% in air grading and 31% in air dig and dump, with negligible impact on cycle time. General excavator operation is typically a mix of grading, dig and dump, and idling. For electric machines, the idle portion can be excluded as the electric motor is easily stopped and started when needed. Assuming a duty cycle of 30% grading and 70% digging, the digital hydraulic system would reduce battery power consumption by 35% without significantly impacting work rate. This would result in 53% longer operating hours with the same battery capacity as the baseline machine, or similar runtime as the baseline with two battery packs instead of three.

The team identified several opportunities for system refinement, but these changes could not be implemented within the project timeframe. First, meter-out losses can be improved with a custom valve design in a system developed from scratch. Second, refined control logic can address inefficiencies discovered during the post-test analysis and improve transient performance and motoring efficiency. Finally, an electrified swing drive – which represents an obvious next step given the electric platform –would further reduce losses and enable additional recuperation.

A path forward

These results confirm the potential of fully digital hydraulic architectures to significantly increase energy efficiency in large excavators. While further testing and validation is called for, the project demonstrates that hydraulic innovation is a practical means to accelerate electrification.

Electric excavators already offer superior operator experience and zero emissions. With digital hydraulics, they can also offer the runtime, productivity and total cost of ownership advantages required for wider adoption across the global construction sector.

Matteo Pellegri, senior engineering manager - digital displacement systems technology, Danfoss Power Solutions, adapted his technical paper on this topic for SAE Media Group. Chris Williamson, senior engineering manager, Danfoss Power Solutions, presented this work at the NFPA Advanced Hydraulics Conference, which was co-located with CONEXPO.