YANMAR Technical Review

Abstract

The mission to achieve carbon neutrality and the increasing demand for environmental performance have driven Yanmar to develop its first electric compact wheel loader – the V8e. This initiative supports Yanmar’s goal of achieving carbon neutrality by 2050, addressing greenhouse gas emissions from human activities, and responding to customer requests to go green. Yanmar aims to develop and market green powertrains compatible with various energy sources, including e-mobility, alternative fuels, engines, and fuel cell systems, without compromising customer convenience.
The V8e designed to match the strength and performance of the V7 – diesel engine version, offers zero emissions, lower noise and reduced vibrations. Challenges such as adapting hydrostat behavior to the electric powertrain, preventing cable overheating, and selecting suitable charging infrastructure were tackled with advanced analysis and innovative solutions. The V8e features robust specifications with the focus on efficiency through software-based demand control.
Prospects for electric construction equipment are promising, driven by legislative measures, subsidies, and decreasing battery costs. Yanmar plans to expand its range of electric machines to meet the growing need for sustainable construction equipment.

1. Introduction

The construction industry is undergoing a significant transformation toward electrification, driven by the global need to reduce greenhouse gas (GHG) emissions and lower environmental impact. As stricter environmental regulations are implemented and incentives for sustainable technologies grow, the demand for electric construction equipment continues to rise. This trend aligns with Yanmar’s mission to achieve zero GHG emissions by 2050, helping customers minimize their environmental impact while maintaining productivity.
In response to these changing demands, Yanmar has developed the V8e electric compact wheel loader. Designed to meet the demanding requirements of modern construction while offering zero emissions, the V8e represents Yanmar’s commitment to delivering high-performance electric solutions that contribute to a more sustainable future.

2. Development Concept and Goals

Yanmar’s V8e electric compact wheel loader is designed to meet the needs of the 4.5-ton class with a 0.8 m³ bucket capacity, while addressing the growing demand for environmentally friendly and sustainable construction equipment. Built on a newly developed platform, the V8e shares its core structure with the diesel-powered V7 and V7-HW models (Fig.1), maintaining the same strength and performance.
The primary objective was to enable customers to adopt new electric technology without compromising performance, functionality, or work efficiency. To achieve this, three key development goals were defined: maintaining productivity, overcoming the limitations of electric technology, and matching the strength and performance of traditional diesel-powered machines.

3. Design Challenges and Solutions

To achieve the development goals of the V8e—maintaining productivity, overcoming the limitations of electric technology, and achieving the strength and performance of traditional diesel-powered machines—five key design challenges were identified. Each challenge addresses a specific area necessary for reaching these objectives, with solutions targeted to meet the demands of modern construction.

3.1. Adapting the behavior of a hydrostat to the electric drivetrain through software alignment

Understanding the benefits and operational characteristics of conventional hydrostatic drivetrains, used in diesel-engine wheel loaders, was crucial for developing the electric drivetrain while maintaining robust performance. Hydrostatic drives provide notable advantages, including automatic deceleration when the operator releases the pedal. Hydraulic resistance slows the machine, reducing brake wear and enhancing control on slopes by preventing rollback when the brake is released. Additionally, in tasks like pushing a bucket into a pile, the dynamic adjustment (DA) control prevents wheel slippage by managing torque effectively.
Replicating this intuitive behavior in an electric drivetrain posed challenges during software development. Electric motors lack natural resistance, making it difficult to control the machine on slopes, leading to abrupt movements and rollback. Early iterations struggled with keeping the machine stationary, and pressing the pedal too hard caused jerky movements.
Yanmar addressed these issues by developing a torque-controlled electric drive, which mirrors the smooth behavior of hydrostatic systems. This system enhances precision, efficiency, and low-speed control, ensuring smooth operation on slopes and predictable rollback. High-load tasks, like pushing into a pile, are handled without wheel slippage. Feedback from experienced operators guided the software refinement process. In addition to replicating hydrostatic functionality, the electric drivetrain offers energy recuperation, regenerating energy during braking, reversing, and downhill driving. This increases autonomy and efficiency.

3.2. Temperature measurement method in the power distribution unit prevents overheating of the high voltage cables

The Power Distribution Unit (PDU) in the V8e is a key component that distributes power from the 48V battery to subsystems like the electric drivetrain, ePTO (electric motor for the hydraulic pump), and control electronics. It ensures safe power allocation using fuses, relays, and circuit breakers, protecting against overloads and electrical faults. A standout feature is the temperature monitoring of high-voltage cables, which supply power to the drivetrain motor and ePTO (Fig.2). These cables must handle peak currents without overheating, such as when driving up steep slopes.
Competitors typically protect cables by immediately limiting peak currents, which significantly reduces driving speed on steep inclines, causing delays. In contrast, the V8e’s PDU uses temperature sensors (Fig.2) to monitor cable heat in real-time, applying power limitations only after reaching a specific threshold. This allows the V8e to maintain maximum possible speed on inclines until the limit is reached, enhancing both performance and efficiency.

In a recent field test at the quarry, the V8e demonstrated a significant advantage over competitors lacking temperature monitoring technology. This test involved a head-to-head challenge on a steep slope, demonstrating the performance impact of advanced temperature monitoring (Fig.3). During the race, the V8e’s intelligent temperature monitoring system continuously assessed its operational heat levels, allowing it to maintain peak efficiency under demanding conditions. In contrast, the competitor’s machine, unable to monitor and adapt to temperature changes, quickly began to reduce speed, unable to sustain the same performance level. By the time the V8e reached the top of the incline, the competitor’s machine lagged considerably behind. This disparity highlights how real-time temperature monitoring can prevent thermal throttling, maximize productivity, and ensure sustained performance, particularly in high-demand environments like quarries.

3.3. Selection of charging infrastructure to ensure customer acceptance

Customer satisfaction and acceptance are a key part of Yanmar’s primary concerns. Especially when it comes to new technologies, barriers of customers’ acceptance must be avoided. Therefore, it was crucial to select the appropriate charging infrastructure, which has minimal impact on daily work routines.
The on-board chargers of the V8e deliver a charging power of 11 kW, or optionally 22 kW, enabling charging times of approximately 1.5 hours from 20% to 80% State of Charge.

Table 1 Recharging times from 20%-80% SOC depending on the power source

The decision to integrate fast on-board chargers, rather than relying on off-board fast chargers as many competitors do, was made consciously. Off-board chargers were considered impractical for daily operations, as customers would need to remember to bring them to the worksite. Additionally, the large and heavy off-board chargers would require transportation, increasing logistical complexity. Having all necessary charging equipment integrated into the machine is a significant advantage for the operator.
When it came to selecting a suitable charging connector for the V8e wheel loader, the decision to use the Type 2 charging socket was made based on industry standards and operational versatility. The Type 2 connector, widely adopted across the automotive industry, ensures compatibility with a broad range of public charging infrastructure and wallbox systems. In scenarios where neither public nor fixed charging solutions are available, the V8e offers additional flexibility with the JUICE BOOSTER®. This portable Type 2 charging device, included as part of the machine’s standard equipment, allows charging from a variety of power sources, including battery power generators (Fig.4). The provided adapters enable charging from any conventional household or industrial sockets worldwide.

3.4. Software-based demand control of the ePTO improves efficiency

An efficient hydraulic system was a primary objective in the development of the V8e, essential for maintaining productivity by achieving extended autonomy. A key feature enhancing this efficiency is the software-based demand control of the ePTO, which is the electric motor driving the hydraulic pump. The demand control system delivers only the necessary hydraulic flow to the actuators, optimizing energy use.
Figure 5 illustrates the working principle of the demand control, when the operator moves the joystick. The main control valve (Fig.5 -right side) is equipped with spool sensors indicating the precise position of the spools. The sensor signal (electrical voltage output) is sent to the control units, which process the signal based on the flow rate chart. The software utilizes this data to precisely regulate the hydraulic flow from the pump via the ePTO, ensuring accurate operation of the hydraulic actuator (Fig.5 -left side). In standby mode, the ePTO operates at a minimal speed of 100 rpm to maintain safety-critical components like steering. In traditional diesel-engine wheel loaders, stand by speeds are typically around 1000 rpm, causing the hydraulic pump to run continuously and consume up to 0.5 kWh of energy. Due to the significantly reduced standby speed of the ePTO, it can achieve energy savings of up to 90%.
The operator usually plays a crucial role in determining the power consumption of diesel engine driven machinery. In many cases, operators may maintain high engine speeds, even when full hydraulic flow is unnecessary, leading to excessive energy use. However, demand control systems mitigate this by providing consistent and energy-efficient performance, regardless of the operator’s behavior or experience. The integration of specialized working modes on the V8e, such as ECO-, Forklift-, Bucket- and Power-Mode, further simplifies the process, enabling operators to select the most efficient setting for the task at hand.

3.5. Selection of the battery

Yanmar selected LFP batteries for the V8e due to their excellent characteristics. Although LFP batteries are heavier and larger due to lower energy density, Yanmar leveraged this to their advantage by using the heavier battery as a counterweight, reducing the need for additional ballast, optimizing both performance and design. Additionally, there was sufficient installation space in the V8e to accommodate the larger batteries.
The LFP battery in the V8e is equipped with an integrated heating system, ensuring full power delivery even at cold temperatures as low as -20°C. Furthermore, thanks to the integrated temperature management system, charging at cold ambient temperatures can always occur at full power.
Another significant advantage of the LFP battery is its lifespan. The battery has a lifespan of over 5,000 complete charge cycles, with 80% remaining SOH (state of health).
The LFP battery in the V8e has a capacity of 39.9 kWh. Optionally, the V8e can be equipped with a battery capacity of 53.2 kWh, which extends the operating time of the loader.
To determine and compare autonomy in wheel loaders, the so-called V-loading cycle (Fig.6) is used. A typical task for a wheel loader is transporting bulk material between two stockpiles or between a stockpile and a truck. This task results in a repetitive sequence of movements. When viewed from above, the driving motion resembles a “V”, hence the name V-loading cycle.

The operating times in Table 2 result from the different battery capacities. Since the V-loading cycle represents 100% machine utilization, the daily operating time under real-world conditions can be extrapolated accordingly.

Table 2 Overview of the battery range

4. Machine Specifications

The V8e is a 4.5-ton compact wheel loader with articulated steering, designed for stability and maneuverability. It features an Articulation-Oscillation Joint (AOJ), which ensures maximum stability and smooth operation on uneven terrain. The structure is engineered to maintain a low height of under 2.5 meters, while still delivering excellent lifting power, capable of handling over 1.8 tons on pallet forks. The machine’s intelligent software provides multiple working modes - ECO, Bucket, Fork, Power-Mode, which are selectable via a 3.5-inch display. This allows the operator to adjust performance to match the task at hand, optimizing energy consumption and productivity.

Table 3 V8e vs. V7-HW machine specifications

5. Conclusions

This article has described the development of the V8e electric wheel loader, focused on achieving the goals of maintaining productivity, overcoming electric technology limitations, and matching the strength and performance of traditional diesel-powered machines. Meeting these goals required addressing five critical design challenges. Adapting hydrostatic behavior to the electric drivetrain enabled the V8e to deliver smooth, intuitive control, while preventing overheating of high-voltage cables ensured reliable performance under heavy loads. Additionally, selecting the appropriate charging infrastructure minimized operational disruptions by providing flexible, easy-to-integrate charging options. To enhance energy efficiency, optimizing hydraulic performance through software-based demand control enabled precise power adjustments, extending operational autonomy. Finally, choosing the right battery technology balanced cost, safety, runtime and durability, using the LFP battery as both a power source and counterweight. Together, these solutions enable the V8e to meet the demands of modern construction while setting a new standard in sustainable, high-performance machinery.
As the global trend toward greener solutions continues, Yanmar aims to drive innovation, expanding its electric construction equipment lineup, supporting carbon-neutral goals, and helping customers reduce their environmental footprint while maintaining high productivity and operational efficiency.