in the EPFS520 ?

General Information:
EPFS520 Battery Impedance Tester (also called Battery Internal Resistance Tester) is a measuring instrument used to measure the internal resistance, voltage and temperature of rechargeable batteries such as lead batteries and lithium batteries to determine the health of the battery. This instrument uses the AC 4-terminal test method to measure the internal resistance of the battery, which can measure the correct measurement value without being affected by the contact resistance between the test wire, terminal and battery electrode. It also has functions such as data storage, data access, alarm, and automatic shutdown. The whole machine is high-grade and beautiful, with wide measuring range, high resolution, convenient operation, easy to carry, accurate, reliable, stable performance, and strong anti-interference ability. It is an indispensable instrument for battery production, battery installation, equipment production, and equipment maintenance.

EPFS520 Battery Impedance Tester is controlled by a microprocessor, and the internal 16-bit ADC can accurately detect the battery internal resistance, voltage and temperature. It is characterized by measuring without stopping the UPS system, using AC low-resistance measurement and noise reduction technology, without stopping the normal operation of the equipment under test, and measuring under the running state, which greatly shortens the test time. At the same time, it has the functions of data storage, histogram display, and data upload to the computer.

Resistance Measuring Precision:

Measuring Range

Max. Display


Measuring Accuracy

Measuring Current

3 mΩ

3.100 mΩ

1 uΩ

±1.0 % rdg. ±10 dgt.

200 mA

30 mΩ

31.00 mΩ

10 uΩ

±1.0 % rdg. ±6 dgt.

200 mA

300 mΩ

310.0 mΩ

100 uΩ

20 mA

3 Ω

3.100 Ω

1 mΩ

2 mA

Voltage Measuring Precision:

Measuring Range

Max. Display


Measuring Accuracy

7 V

±7.100 V

1 mV

±0.1 % rdg. ±6 dgt.

70 V

±71.00 V

10 mV

Temperature Measuring Precision:

Measuring Range

Max. Display


Measuring Accuracy






The above accuracy guarantee is limited to the factory standard test leads. When using non-standard test leads or extension cables, this accuracy table is also applicable after zero adjustment.

Main technical data table:


Battery internal resistance measurement, battery voltage measurement, temperature measurement

Accuracy guaranteed temperature and humidity

23℃±5, below 75%rh

Power supply

DC 3.7V lithium battery

Resistance resolution

1 uΩ

Voltage resolution

1 mV

Temperature resolution


Measuring range

Internal resistance measurement: 0.000mΩ~3.100 Ω (composed of 4 ranges)

Voltage measurement: 0.000V~±71.00V (consisting of 2 ranges)

Temperature measurement: -10.0~60.0 (single range configuration)

Maximum input voltage

DC 70V (between + measurement terminal and-measurement terminal), no AC input

Measurement method

Internal resistance measurement: AC 4-terminal test method, open terminal voltage 3V max

Measuring current: 2.0mA~200mA (different measuring currents in different ranges)

Temperature measurement: NTC temperature sensor (10KΩ at 26)

A/D conversion method: successive approximation type

Display update frequency: 5 times/second

Response time


Measure time

About 2 seconds

LCD size

70.1mm×52.6mm / 3.5 inches (320*240 resolution 16-bit true color screen)

Instrument size

LWH: 190mm×121mm×51mm

USB interface

With USB interface, the stored data can be uploaded to the computer, saved and printed



Hold and store function

There are manual retention and storage, automatic retention and storage

Alarm function

When the measured value exceeds the alarm set value, an alarm will be issued

Battery voltage

Real-time display of battery power, reminding to charge in time when battery voltage is low

Automatic shut-down

There is no operation when power on, and it will automatically power off after about 15 minutes (this function can be turned off in the settings)

Power consumption

300mA MIN / 500mA MAX


Meter: 480g (including battery)

Working temperature and humidity

-10℃~40; below 80%RH

Storage temperature and humidity

-20℃~60; below 70%RH

Insulation resistance

Above 20MΩ (500V between circuit and case)

Withstand voltage

AC 3700V/RMS (between circuit and case)

External magnetic field


External electric field


Suitable for safety regulations

IEC 61010