Nagano, Japan, December 10, 2025 — Hioki E.E. Corporation proudly announces the launch of the RM3546 Resistance Meter, the company’s most advanced nanohm-class measurement solution for EV and ESS battery manufacturing.

Engineered with 1 nΩ resolution, A-OVC thermal-noise suppression, Active Circuit Protection up to DC 60 V, and A-TC temperature correction, the RM3546 enables manufacturers to evaluate welding electrical performance directly, supporting safer, more efficient, and more competitive battery production from R&D to fully automated production lines.

Development Background

Global demand for EVs and battery energy storage continues to surge, pushing manufacturers toward higher-volume, higher-voltage production with increasingly strict quality requirements. 
According to the International Energy Agency (IEA), global battery demand surpassed 1,000 GWh (1 TWh) in 2024. This momentum continues to accelerate in 2025, with total demand projected to exceed 1.2 TWh. From a medium- to long-term perspective, IEA projections indicate that EV battery demand alone will expand to 2.5 TWh by 2030. ^*1 At the same time, large-scale Energy Storage Systems (ESS) supporting the power grid are rapidly becoming widespread. To achieve the COP28 goal of tripling renewable energy, the IEA estimates that global energy storage capacity must reach 1,500 GWh (1.5 TWh) by 2030, predicting that batteries will account for over 90% of this capacity. ^*2 Furthermore, BloombergNEF forecasts that the annual deployment of ESS will reach approximately 250 GW/1,000 GWh by 2035, with the global cumulative deployment exceeding 2.0 TW/7.3 TWh. This represents a twelvefold increase in cumulative deployment compared to 2024. ^*3
As battery packs scale up, busbar weld resistance has become a critical parameter linked to safety, performance, and durability. Small resistance variations can cause localized heating, energy loss, or accelerated degradation. Production lines therefore require instruments that can reliably measure weld performance at the nanohm level, withstand high-voltage environments, and operate with minimal takt delay. The RM3546 was developed specifically to meet these demands.

• *1:IEA World Energy Outlook 2025 / Global EV Outlook 2025
• *2:IEA Special Report: Batteries and Secure Energy Transitions
• *3:BloombergNEF: Energy Storage Market Outlook 2H 2025 (Oct 2025)

Key Features

1. 1 nΩ Resolution and Advanced A-OVC for Stable Nanohm-Level Measurement

For busbar welding quality control, nanohm-level precision is essential. Yet thermal electromotive force (thermal EMF) caused by slight temperature differences in fixtures, cables, and probes can cause readings to “jump,” making stable evaluation difficult.
The RM3546 solves this with:

•    1 nΩ resolution (1000 μΩ range)
    Captures ultra-fine resistance changes in battery-pack R&D, prototype evaluation, and strict inline inspection.
•    Advanced-Offset Voltage Correction (A-OVC)
    A further evolution of Hioki’s proven noise-cancelling technology, significantly suppressing thermal EMF across a wide range of environments, from controlled labs to temperature-varying production floors.

Result: 
Reliable, repeatable nanohm-level measurement from R&D to mass production.

2. New Active Circuit Protection (Up to DC 60 V) Protects Instruments and Uptime

Accidental probe contact with energized battery cells or modules is a leading cause of measurement-instrument failure on battery production lines. The RM3546 incorporates Active Circuit Protection (ACP) that withstands applied voltages of up to DC 60 V, helping to:

•    Protect the instrument from damage during mis-contact or mis-wiring
•    Reduce unplanned downtime and repair costs
•    Maintain stable, continuous operation in high-voltage environments

Result:
A production-ready meter built for safety, uptime, and long-term reliability.

3. Up to 9 Ω Path-Resistance Tolerance and Flexible System Integration

Scaling production lines often require longer cables, worn probes, or multiple scanner relays—all of which increase path resistance and can destabilize measurements. The RM3546 addresses this by:

•    Expanding path-resistance tolerance to up to 9 Ω (in 500 mA mode), more than 2.5 times higher than previous models (3.5 Ω)
      This offers greater flexibility in line design and supports long-term stable operation.
•    Supporting Hioki’s proven multiplexer systems (e.g., SW1001/SW1002, SW9001) and an internal multiplexer board option
      Enables easy construction of high-speed, multi-channel inline inspection systems.
•    Recommended probe kits (L9773 series) to support effective probe selection and jig design

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

4. A-TC (Advanced-Temperature Correction) for Fast, Accurate Post-Weld Evaluation

Immediately after welding, the joint heats rapidly, creating strong thermal EMF that typically requires a cooling delay before measurement. This slows both R&D evaluation and production takt time.
Hioki’s new Advanced-Temperature Correction (A-TC), a new function that, when used with the dedicated PC application, enables:

•    Accurate resistance measurement within seconds after welding
•    Reliable evaluation under hot-weld conditions
•    Reduced waiting time during tests and inline inspection

Result:
Real-time welding feedback for faster development cycles and more efficient production.

Main applications

EV/ESS battery R&D

Precision evaluation of next-generation batteries, electrode materials, and welding processes

Detection of minute resistance changes in new materials and designs

Battery Pack and Module Production

Inline, full-count inspection of busbar welding resistance

Cell-to-cell connection resistance and fuse resistance measurement

Other high-precision DC resistance measurements

EV charging connectors and infrastructure components

Power distribution components for data centers and industrial systems

Product Lineup

Resistance Meter RM3546
Multiplexer Unit Z3003
Probe Kit L9773

For more information

Learn more about the RM3546 Resistance Meter.

Contact us

For inquiries such as quotes, demonstrations, and trial usage, please use Hioki’s contact form for a personalized reply from your closest or most appropriate Hioki representative.

• The information provided is current as of the date of publishing.
• Please note that prices, specifications, and other information contained in this texts are subject to change without notice.
• The company names and product names used in this text are registered trademarks or trademarks of their respective companies.

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