FNIRSI HRM-10 Battery Internal Resistance Measurement Errors and Troubleshooting Malaysia

Introduction

Accurate battery internal resistance measurement is important when inspecting rechargeable batteries, comparing lithium-ion cells and troubleshooting battery performance problems.

However, technicians may sometimes encounter unstable resistance readings, inconsistent measurements or unexpected results when using a battery resistance tester.

These problems do not always indicate a defective battery.

Measurement differences may result from probe contact quality, battery temperature, state of charge, test lead condition or incorrect testing procedures.

The FNIRSI HRM-10 Battery Internal Resistance Tester uses an approximately 1kHz AC measurement method and four-wire Kelvin probes to measure battery internal resistance.

Understanding the factors that influence measurement accuracy can help technicians obtain more consistent results.

This guide explains common FNIRSI HRM-10 measurement problems and practical troubleshooting methods for electronics repair workshops, battery service businesses and industrial maintenance teams in Malaysia.

Why Battery Internal Resistance Measurement Accuracy Matters

Battery internal resistance is often measured in milliohms (mΩ).

One milliohm equals 0.001 ohm.

When measuring low-resistance battery cells, small changes in the measurement setup may affect the displayed result.

For example, a technician may obtain different readings when measuring the same cell repeatedly.

Possible causes include:

• Inconsistent Kelvin probe contact

• Contaminated battery terminals

• Battery temperature changes

• Different states of charge

• Damaged or loose test leads

• Electrical interference

• Instrument resolution and accuracy limitations

A repeatable measurement process helps distinguish actual battery differences from testing inconsistencies.

Understanding the FNIRSI HRM-10 Measurement Method

The FNIRSI HRM-10 is designed for battery internal resistance and DC voltage measurement.

Its internal resistance function uses an approximately 1kHz AC test method.

This means the instrument measures an AC electrical characteristic of the battery.

The result is not necessarily identical to the battery's DC resistance under a particular load.

The HRM-10 also uses a four-wire Kelvin connection to reduce the influence of current-carrying test lead resistance.

FNIRSI HRM-10 Main Specifications

Important: Measurement accuracy and resolution depend on the selected range and manufacturer's specifications. Always follow the latest operating manual.

Problem 1 - Unstable Battery Internal Resistance Reading

One of the most common complaints is an unstable resistance reading.

A technician may measure the same battery several times and obtain slightly different results.

Possible Causes

• Poor probe contact

• Movement of the test probes

• Oxidized battery terminals

• Loose measurement connections

• Electrical noise

• Instrument resolution limitations

Troubleshooting Steps

Step 1: Confirm the battery is compatible with the tester.

Step 2: Check the condition of the Kelvin probes.

Step 3: Position the probes securely on the battery terminals.

Step 4: Avoid moving the probes during measurement.

Step 5: Repeat the measurement under the same conditions.

Step 6: Compare the results for consistency.

If the reading remains unstable, inspect the leads and consult the instrument manual.

A changing resistance reading does not automatically mean the battery is defective.

Problem 2 - Internal Resistance Reading Is Unexpectedly High

A battery may display a higher resistance value than expected.

This can occur because of battery condition or measurement setup.

Possible Causes

• Battery ageing

• Low battery temperature

• Poor electrical contact

• Incorrect comparison reference

• Different battery chemistry

• Different state of charge

• Damaged battery terminals

Recommended Action

First, verify the measurement setup.

Repeat the test using stable probe contact.

Compare the reading with the manufacturer's specifications or suitable reference measurements for the same battery model.

If the high reading persists, additional battery evaluation may be necessary.

Do not reject a battery based on one resistance reading without verifying the measurement conditions.

Problem 3 - Resistance Reading Changes When Probe Position Changes

The position of the Kelvin probes can influence measurement repeatability.

Although four-wire Kelvin measurement reduces test lead resistance effects, it does not eliminate every source of contact-related error.

Possible Causes

• Different terminal contact points

• Surface contamination

• Unstable probe pressure

• Poor contact geometry

• Damaged probe tips

Recommended Action

Use a consistent probe placement method.

Ensure the contact surfaces are suitable for measurement.

Avoid touching both battery terminals with conductive objects that could cause a short circuit.

Consistent Kelvin probe placement is important for repeatable battery resistance measurements.

Problem 4 - Battery Voltage Appears Normal but Resistance Is High

A battery can show a normal open-circuit voltage while having higher internal resistance.

This is because voltage and internal resistance measure different characteristics.

For example, two lithium-ion cells may have similar voltage readings but different internal resistance values.

Illustrative measurements only. These are not universal battery acceptance limits.

Cell C has a higher resistance reading.

However, the technician should verify the result and consider additional testing.

Normal voltage does not guarantee normal internal resistance or full battery capacity.

Problem 5 - Different Results at Different Temperatures

Battery internal resistance can change with temperature.

A lithium-ion battery measured in a cool environment may produce a different reading from the same battery measured at a warmer temperature.

This is especially relevant when comparing batteries stored in different locations.

Recommended Action

For meaningful comparisons:

• Record the battery temperature

• Use similar environmental conditions

• Allow batteries to reach a stable temperature

• Avoid comparing hot and cold cells directly

• Follow manufacturer temperature limits

Do not heat or cool batteries outside their approved operating conditions merely to obtain a particular resistance reading.

Problem 6 - Different Results at Different States of Charge

Battery state of charge may influence internal resistance.

Two cells of the same model may produce different readings if their charge conditions differ.

Recommended Action

Compare batteries at similar states of charge whenever possible.

Record voltage and relevant testing conditions.

Use manufacturer-recommended procedures when establishing battery quality control criteria.

Battery internal resistance comparisons should use consistent conditions rather than arbitrary measurements.

Problem 7 - Resistance Reading Is Too Low or Near the Instrument Limit

Some high-capacity lithium battery cells have extremely low internal resistance.

When the measured resistance approaches the instrument's resolution or accuracy limits, small differences may not be reliably distinguishable.

Example

Consider two cells with actual resistance values close to one another.

If the instrument's uncertainty is comparable to the difference between the cells, the displayed readings may not support a meaningful ranking.

Recommended Action

Check the HRM-10's specified resolution and accuracy for the selected measurement range.

For very low resistance applications, consider a dedicated professional battery impedance instrument with suitable measurement performance.

Display resolution and measurement accuracy are not the same thing.

Problem 8 - Battery Resistance Changes Between Testers

Two battery internal resistance testers may display different values for the same battery.

Possible reasons include:

• Different measurement frequencies

• Different measurement methods

• Different accuracy specifications

• Different test fixtures

• Different contact conditions

• Calibration differences

For example, an approximately 1kHz AC resistance reading may differ from a resistance value obtained using a DC pulse method.

Recommended Action

Compare instruments only when their measurement methods and conditions are understood.

For formal quality control, use a validated measurement procedure and suitable reference equipment.

Problem 9 - Incorrect Reading Caused by Test Lead Problems

Test leads are an important part of the measurement system.

Damaged insulation, loose connectors or worn probe tips may affect measurement quality.

Recommended Action

Inspect the test leads before use.

Check for:

• Damaged cables

• Loose connectors

• Bent or worn probe tips

• Contaminated contacts

• Exposed conductors

Replace damaged accessories with suitable manufacturer-approved parts.

Do not continue using unsafe test leads.

Problem 10 - Incorrect Interpretation of Battery Resistance

Sometimes the measurement itself is consistent, but the conclusion is incorrect.

A technician may assume that a particular milliohm reading proves a battery is good or bad.

However, normal internal resistance depends on:

• Battery chemistry

• Battery model

• Cell capacity

• Manufacturer design

• Temperature

• State of charge

• Measurement method

There is no universal resistance value suitable for every battery.

Always interpret resistance measurements using the correct battery specifications and testing conditions.

FNIRSI HRM-10 Troubleshooting Summary

How to Improve Battery Internal Resistance Measurement Repeatability

A consistent measurement procedure can improve the usefulness of resistance readings.

Step 1 - Identify the Battery

Confirm the model, chemistry and nominal voltage.

Step 2 - Inspect the Battery

Check for physical damage.

Do not test visibly unsafe cells.

Step 3 - Standardize Temperature

Measure comparable cells under similar temperature conditions.

Step 4 - Standardize State of Charge

Where practical, compare cells at similar charge conditions.

Step 5 - Inspect the Kelvin Probes

Check the condition of the leads and contact tips.

Step 6 - Use Consistent Contact Points

Position the probes consistently.

Step 7 - Repeat Measurements

Take repeat readings when results appear inconsistent.

Step 8 - Record the Results

Document voltage, resistance, temperature and battery identification.

Step 9 - Compare with Appropriate References

Use manufacturer specifications or validated baseline measurements.

Step 10 - Investigate Unusual Results

Use additional testing when the resistance reading alone is insufficient.

Example - Repeated Resistance Measurements

A technician measures one compatible lithium-ion cell several times.

Illustrative results only.

The readings are relatively consistent.

Now consider another measurement sequence:

The second sequence shows greater variation.

Before drawing conclusions about the battery, the technician should investigate probe contact, test lead condition and other measurement factors.

Repeatability is an important part of reliable battery resistance testing.

FNIRSI HRM-10 Measurement Accuracy vs Resolution

These two terms are often confused.

Measurement Resolution

Resolution refers to the smallest change that an instrument can display.

Measurement Accuracy

Accuracy describes how close the measured result is to the actual value within the instrument's specified conditions.

An instrument may display several decimal places without being accurate to every displayed digit.

For professional battery inspection, both resolution and accuracy should be considered.

When Should You Use a Professional Battery Impedance Tester?

The FNIRSI HRM-10 may be suitable for many workshop-level battery measurements.

However, some applications require more specialized equipment.

Examples include:

• Very low resistance measurements

• Formal production quality control

• High-volume automated testing

• Critical UPS battery maintenance

• High-voltage battery systems

• Traceable laboratory measurements

For these applications, choose instruments with suitable specifications, safety ratings and measurement traceability.

Frequently Asked Questions

Q1. Why does my FNIRSI HRM-10 resistance reading keep changing?

Possible causes include unstable probe contact, temperature differences, test lead problems or measurement limitations.

Q2. Why is my battery resistance reading higher than expected?

Possible causes include battery ageing, low temperature, poor contact or incorrect comparison criteria.

Q3. Does FNIRSI HRM-10 use four-wire Kelvin measurement?

Yes. It uses a four-wire Kelvin connection to reduce the influence of test lead resistance.

Q4. Can battery temperature affect internal resistance?

Yes. Battery internal resistance can change with temperature.

Q5. Why do two battery testers show different resistance values?

They may use different measurement frequencies, methods, accuracy specifications or test connections.

Q6. Can FNIRSI HRM-10 determine battery health from one measurement?

No. Internal resistance is only one parameter and should be interpreted alongside other appropriate battery information.

Conclusion

Battery internal resistance measurement errors can result from several factors, including probe contact, temperature, state of charge, test lead condition and instrument limitations.

The FNIRSI HRM-10 Battery Internal Resistance Tester uses an approximately 1kHz AC measurement method and four-wire Kelvin probes to support low-resistance battery measurements.

For electronics repair workshops, battery service businesses and industrial maintenance teams in Malaysia, consistent measurement procedures are important for obtaining useful results.

Reliable battery testing requires both a suitable instrument and correct measurement technique.

Where to Buy FNIRSI HRM-10 in Malaysia?

MTM Precision Sdn Bhd supplies electrical testing instruments, battery inspection equipment and industrial measuring tools in Malaysia.

Customers searching for FNIRSI HRM-10 Battery Internal Resistance Tester Malaysia can contact MTM Precision for product information, quotations and availability.

We support customers across Kuala Lumpur, Selangor, Johor, Penang, Melaka, Negeri Sembilan, Perak, Pahang, Kedah, Kelantan, Terengganu, Perlis, Sabah and Sarawak.

Contact MTM Precision Sdn Bhd

MTM Precision Sdn Bhd

Showroom & Service Centre

No. 29-1 & 29-2, Jalan Bandar 18,
Pusat Bandar Puchong,
47160 Puchong, Selangor, Malaysia.

Tel: 03-8080 7172

WhatsApp: +6016-660 7346

Email: mtmpre@yahoo.com

Website: www.mtmpre.com.my

Contact MTM Precision today for FNIRSI HRM-10 product information, quotations and availability in Malaysia.