AC 4-Wire Battery Voltage & Internal Resistance Tester | 99 Groups
AC 4-Wire Battery Voltage & Internal Resistance Tester | 99 Groups
1.77-Inch Voltage & Internal Resistance Tester — AC 4-Wire Method
Get precise, repeatable battery measurements with this compact AC 4-Wire Method Voltage and Internal Resistance Tester. Whether you're sorting battery cells for DIY power packs, evaluating lithium or LiFePO4 batteries, or benchmarking cells for an electronics project, this handheld tester delivers high-resolution readings and intuitive grading — all in a pocket-sized package. Made in Mainland China.
Key Features
- High-Resolution Measurement: Voltage range 0.001 V – 60.00 V (resolution 0.001 V); internal resistance range 0.1 mΩ – 6.999 Ω (resolution 0.1 mΩ).
- AC 4-Wire Testing Method: Eliminates lead-resistance errors for more accurate internal resistance readings compared to 2-wire methods.
- 99-Group Data Storage: Manually save and review up to 99 sets of voltage and internal resistance measurements directly on the device — no PC required.
- 4-Grade Sorting (A / B / C / D): Built-in internal resistance grading and voltage reference evaluation make cell matching and quality screening quick and intuitive.
- 1.77-Inch Display: Clear, bright screen with 9 levels of adjustable backlight brightness for comfortable use in any lighting condition.
- Adjustable Auto Power-Off: Set standby time from 1 to 9 minutes; screen-off standby current drops below 1 mA to conserve battery.
- Built-In 4056 Charging Module: Supports ternary lithium and LiFePO4 battery power supply and charging — power it with any standard 5 V / Type-C adapter.
- 90% Pre-Assembled, Compact Body: Measures just 73.2 × 72 × 24 mm — easy to set up and ideal for maker and DIY projects.
- Fine-Tuning Support: Both voltage and internal resistance displays support display fine-tuning for calibration adjustments.
Specifications
| Parameter | Value |
|---|---|
| Working Voltage | DC 5 V (do not exceed rated voltage; 5 V adapter & Type-C cable NOT included) |
| Testing Principle | AC 4-Wire Method |
| Voltage Test Range | 0.001 V – 60.00 V, Resolution: 0.001 V |
| Internal Resistance Range | 0.1 mΩ – 6.999 Ω, Resolution: 0.1 mΩ |
| Data Recording | 99 groups (manual store & recall) |
| Grading | 4 grades: A, B, C, D |
| Backlight | 1–9 levels adjustable |
| Auto Power-Off | 1–9 minutes (adjustable) |
| Standby Current | 30 mA (screen on); <1 mA (screen off) |
| Signal Cable | USB-4P Signal Acquisition Cable |
| Dimensions | 73.2 × 72 × 24 mm |
| Country of Origin | Made in China |
What's in the Box
- 1× Voltage & Internal Resistance Tester
- OR 1× Test Clip
- OR 1× Test Stand
Note: 5 V power adapter and Type-C cable are NOT included. Battery is NOT included.
Who Is This For?
This tester is perfect for electronics enthusiasts, hobbyist makers, EV battery builders, RC car modders, solar storage DIYers, and anyone who needs to sort, match, or evaluate individual cells before assembling a battery pack. The 4-grade sorting system removes guesswork from cell matching and the on-device 99-group memory means you can test an entire batch without needing a laptop nearby.
For general guidance on electrical measurement standards and safety, visit the NIST Calibration Services page — a trusted resource on metrology and measurement accuracy.
Frequently Asked Questions
Q: What is the AC 4-Wire Method and why does it matter for internal resistance testing?
A: The AC 4-Wire (Kelvin) method uses separate current-source and voltage-sense leads, which eliminates the resistance of the test leads themselves from the measurement. This is essential when measuring very low internal resistance values (in the milliohm range), where even a few milliohms of lead resistance would otherwise skew the result. The result is a far more accurate reading of the battery cell's true internal resistance.
Q: What types of batteries can I test with this tester?
A: This tester supports any cell or battery with a voltage between 0.001 V and 60 V, making it compatible with standard lithium-ion (18650, 21700, pouch cells), LiFePO4, NiMH, NiCd, lead-acid, and many other rechargeable cell chemistries. The built-in 4056 charging module specifically supports ternary lithium and LiFePO4 cells for powering the unit itself.
Q: Does the tester need batteries to operate, and what power supply does it need?
A: The tester operates on DC 5 V via a Type-C connection. It does NOT come with a battery, 5 V adapter, or Type-C cable — you will need to supply your own standard 5 V USB adapter and Type-C cable. Do not exceed 5 V to avoid damaging the unit.
Q: How does the 4-grade sorting (A/B/C/D) work?
A: You can configure reference thresholds for voltage and internal resistance. Once set, the tester automatically grades each measured cell into one of four categories (A, B, C, or D) based on how it compares to your defined thresholds — making it fast and easy to sort large batches of cells into quality tiers for battery pack building or quality control.
Q: Can I review previously saved measurements on the device?
A: Yes. The tester stores up to 99 groups of voltage and internal resistance data in on-device memory. You can scroll through and review all saved records directly on the 1.77-inch screen without connecting to a computer.