HIOKI is pleased to announce the launch of the new-generation RM3546 Resistance Meter, a nano-ohm-level (nΩ) measurement solution developed for battery manufacturing in electric vehicle (EV) and energy storage system (ESS) applications.

The RM3546 features 1 nΩ resolution, A-OVC offset voltage compensation, active circuit protection up to 60 V DC, and A-TC temperature compensation. It enables manufacturers to directly evaluate the electrical performance of welded joints and supports battery production from the R&D stage through fully automated production lines, helping make battery manufacturing safer, more efficient, and more competitive.

Development Background

Global demand for electric vehicles (EVs) and battery energy storage continues to grow, driving manufacturers to transition toward production systems with greater capacity and higher voltage. At the same time, product quality requirements are becoming increasingly stringent.

According to data from the International Energy Agency (IEA), global battery demand exceeded 1,000 GWh (1 TWh) in 2024. This momentum is expected to accelerate throughout 2025, with total demand projected to exceed 1.2 TWh. In the medium to long term, the IEA forecasts that demand for EV batteries alone will expand to 2.5 TWh by 2030.*1

Meanwhile, large-scale energy storage systems (ESS) that support power-grid operation are rapidly becoming more widespread. To achieve the goal proposed at COP28—the 28th United Nations Climate Change Conference—of tripling global renewable energy capacity, the IEA estimates that global energy storage capacity will need to reach 1,500 GWh (1.5 TWh) by 2030, with batteries expected to account for more than 90% of this capacity.*2

In addition, BloombergNEF forecasts that annual energy storage system deployments will reach 250 GW/1,000 GWh by 2035, while cumulative global deployment capacity will exceed 2.0 TW/7.3 TWh, representing a twelvefold increase compared with 2024.*3

As battery specifications continue to advance, busbar weld resistance has become a critical parameter affecting battery safety, performance, and durability. Even minor changes in resistance can cause localized heating, energy loss, or accelerated aging.

Production lines therefore require inspection instruments capable of reliably measuring nano-ohm-level weld performance, withstanding high-voltage environments, and having minimal impact on production cycle time. The RM3546 Resistance Meter was developed specifically to meet these requirements.

*1 International Energy Agency: World Energy Outlook 2025 / Global EV Outlook 2025
*2 International Energy Agency special report: Batteries and Secure Energy Transitions
*3 BloombergNEF: Energy Storage Market Outlook for the Second Half of 2025 (October 2025)

Product Features

1. Stable nano-ohm-level measurement with 1 nΩ resolution and A-OVC technology

Nano-ohm-level accuracy is essential when inspecting busbar weld quality. However, slight temperature differences among fixtures, test leads, and probes can generate thermoelectric EMF, causing readings to fluctuate and making stable evaluation difficult.

The RM3546 addresses these challenges through the following features:

• 1 nΩ resolution on the 1,000 μΩ range
• Detects extremely small resistance changes during battery-pack R&D, prototype evaluation, and demanding inline inspections.
• Advanced A-OVC offset voltage compensation
• HIOKI’s proven noise-reduction technology has been further enhanced to significantly suppress thermoelectric EMF in environments ranging from controlled laboratories to production floors with fluctuating temperatures.

Result:

Reliable and repeatable nano-ohm-level measurements from R&D through mass production.

2. New active circuit protection up to 60 V DC for safe and stable operation

Accidental contact between a probe and an energized battery cell or module is one of the main causes of measuring-instrument failure on battery production lines.

The RM3546 is equipped with active circuit protection capable of withstanding up to 60 V DC, helping to:

• Prevent instrument damage caused by accidental contact or incorrect wiring
• Reduce unplanned downtime and maintenance costs
• Maintain stable and continuous operation in high-voltage environments

Result:

A production-grade measuring instrument designed for safety, continuous operation, and long-term reliability.

3. Path resistance tolerance up to 9 Ω and flexible system integration

As production lines expand, longer cables, worn probes, and multiple scanning relays are often required. These components increase path resistance and may cause unstable measurement results.

The RM3546 addresses this challenge in the following ways:

• Expands path resistance tolerance to as high as 9 Ω in 500 mA mode, more than 2.5 times the 3.5 Ω tolerance of the previous model. This provides greater production-line design flexibility and ensures stable long-term operation.
• Compatible with HIOKI’s proven multi-channel scanning systems, including the SW1001/SW1002 and SW9001, with an optional built-in multi-channel scanning module available. This enables the rapid construction of high-speed, multi-channel inline inspection systems.
• Recommended for use with the L9773 Series probe kits, supporting efficient probe selection and fixture design.

Result:

Greater design freedom and long-term stability for high-speed, multi-channel inspection systems.

4. Fast and accurate post-weld evaluation with A-TC advanced temperature compensation

After welding, joint temperatures rise rapidly and generate strong thermoelectric EMF. Measurements normally cannot be performed until the joint has cooled, which can delay both R&D evaluation and production cycle times.

HIOKI’s newly developed A-TC advanced temperature compensation function, used together with a dedicated PC application, enables:

• Accurate resistance measurement within seconds after welding
• Reliable evaluation while the welded joint is still hot
• Reduced waiting time for testing and inline inspections

Result:

Real-time weld feedback, shorter development cycles, and improved production efficiency.

Main Applications

EV and energy storage battery R&D

• Accurate evaluation of next-generation batteries, electrode materials, and welding processes
• Detection of minute resistance changes in new materials and new designs

Battery-pack and module production

• 100% inline inspection of busbar weld resistance
• Measurement of inter-cell connection resistance and fuse resistance

Other high-precision DC resistance measurements

• EV charging connectors and infrastructure components
• Data centers and industrial power-distribution systems