UNI-T UT3550 Handheld Battery Internal Resistance & Voltage Tester

The UNI-T UT3550 Battery Internal Resistance Tester is a precision instrument built for professionals who need to catch failing cells before they cause costly downtime. Using a 1 kHz AC injection method combined with a 4-wire Kelvin connection, it measures internal resistance from 0.001 m to 30 at ± 0.5 % accuracy and voltage up to 100 V at ± 0.05 % simultaneously. This dual measurement approach is critical because internal resistance often rises well before voltage drops, giving you an early warning that a standard voltmeter would miss. The 4-wire Kelvin connection eliminates lead and contact resistance from the reading, ensuring reliable milliohm-level accuracy.

A built-in comparison function sorts cells pass/fail against user-set limits for fast battery bank screening, while data logging stores up to 500 groups with CSV export over USB-C for thorough maintenance records. The dual LCD/OLED display, IP65-sealed housing, and rechargeable 7.4 V 2000 mAh Li-ion battery make it well-suited for field use across UPS systems, telecom installations, and industrial battery banks. Battery life runs approximately 5 hours at 20% brightness.