UNI-T UT658B USB Charging Tester, 3–9 V, 0–3.5 A, up to 39999 mAh

UNI-T UT658B USB Charging Tester, 3–9 V, 0–3.5 A, up to 39999 mAh

The UNI-T UT658B is a compact USB charging tester designed for checking USB power supplies, chargers, power banks and charging cables. It displays charging voltage and current in real time and accumulates the electric charge transferred during a charging cycle in mAh. Memory for up to 10 measurement records makes it convenient for comparing different chargers, power sources and USB cables.

Key specifications:
3.0–9.0 V DC • 0–3.5 A DC • 0–39999 mAh • 0.01 V / 0.01 A • 10 memory records

Key features

• Charging voltage monitoring – helps verify the output voltage of a USB charger or power source.
• Current monitoring up to 3.5 A – shows the actual current drawn by the connected device during charging.
• Accumulated charge measurement up to 39999 mAh – useful for monitoring charging processes and comparing USB power sources.
• 10 sets of data storage – allows several charging tests to be stored and compared.
• USB cable comparison by charging current – different cables can be compared under the same test conditions by observing the current delivered to the load.
• Voltage warning function – in a 5 V USB circuit, a warning is displayed when voltage rises above 5.30 V or falls below 4.70 V.
• Backlit LCD – provides direct indication of the measured charging parameters.
• Single-button operation – a short press selects a data record; holding the button for approximately 1.5 seconds clears the current record.
• 10 cm connection lead – provides more flexibility when connecting the tester in confined spaces.

Applications

The UNI-T UT658B is intended for checking USB power and charging circuits. It is useful for everyday users testing chargers and cables as well as technicians performing basic USB power diagnostics.

Typical applications include:

• checking USB charger output voltage;
• monitoring charging current;
• testing power banks;
• comparing USB charging cables;
• monitoring accumulated charge in mAh;
• observing the charging status of USB-powered electronic devices.

Compatibility and limitations

• Operating input voltage is 3.0–9.0 V DC.
• Maximum monitored load current is 3.5 A DC.
• The UT658B is not equivalent to the newer UT658A, UT658C, UT658DUAL or UT658LOAD models. The manufacturer does not specify QC 3.0 / QC 4.0 protocol analysis, D+ / D− voltage measurement or circuit equivalent resistance measurement for the UT658B.
• The mAh value represents electric charge that has passed through the tester. It should not be interpreted as a direct measurement of a battery's nominal capacity independently of test conditions.
• USB cables should be compared using the same charger and the same load.
• The device is intended for low-voltage USB power circuits and is not suitable for direct mains-voltage measurements.

Technical specifications

Parameter	Specification
Product type	USB charging tester
Input voltage	3.0–9.0 V DC
Voltage resolution	0.01 V
Voltage monitoring accuracy	±(1% + 5 digits)
Load current range	0–3.5 A DC
Current resolution	0.01 A
Current monitoring accuracy	±(1% + 5 digits)
Accumulated charge	0–39999 mAh
Data storage	10 records
Voltage warning for 5 V USB	>5.30 V or <4.70 V
Display	Backlit LCD
Control	Push button
Record clearing	Hold button for approx. 1.5 s
Connection lead length	10 cm
Pollution degree	2
Operating temperature	–10…+40 °C
Storage temperature	–10…+50 °C
Relative humidity	<75%
Dimensions	72 × 29 × 12 mm
Net weight	30 g
Conformity	CE

Design and operation

The LCD provides direct indication of the main charging parameters. The tester uses a single control button and provides 10 memory positions for measurement data.

A short button press selects another stored data set. Holding the button for approximately 1.5 seconds clears the current accumulated record.

The 10 cm connection lead provides additional flexibility and reduces the need to place the tester body directly against the USB power source.

Important operating and safety notes

• After connecting the tester to a USB power source, check the displayed output voltage before connecting the device to be charged.
• With a conventional 5 V USB supply, the tester displays a warning when voltage is above 5.30 V or below 4.70 V.
• Do not continue charging if the power-source voltage is unsuitable for the connected equipment.
• Do not exceed the manufacturer's 9 V input-voltage and 3.5 A load-current limits.
• When comparing USB cables, use the same charger and the same load because charging current depends on the power source, cable and connected device.

Package contents

The manufacturer does not provide a separate accessory list for the UT658B in the product specification.