The 4542286 is a Fluke BT521ANG Advanced Battery Analyzer equipped with angled test probes (BTL20ANG) for comprehensive battery string testing and diagnostics. It measures internal battery resistance (3 mO to 3000 mO range), DC voltage (6 V to 1000 V), AC voltage (600 V at 45 Hz to 500 Hz), AC current (up to 400 A with i410 accessory), ripple voltage (600 mV to 6000 mV), frequency (up to 500 Hz), and temperature (0°C to 60°C). The instrument features automatic sequence measurement mode for testing battery strings with integrated data logging, storing up to 100 profiles with 450 batteries each, and includes an intelligent LCD display for on-the-go analysis. It operates over a temperature range of 0°C to 40°C with IP40 protection rating and is ideal for maintenance, troubleshooting, and performance testing of individual stationary battery systems in UPS and backup power applications.