The BT520 is an intelligent battery analyzer probe designed for comprehensive testing and maintenance of stationary battery systems. It features an integrated LCD display and measures internal battery resistance, DC and AC voltage, DC and AC current, ripple voltage, frequency, and temperature using an AC injection method with injected source signal less than 100 mA at 1 kHz. The device supports both automatic and manual sequence testing modes with automatic measurement storage, eliminating the need to manually save each reading, and includes threshold comparison functionality for resistance and voltage with visual and audio feedback cues. The BT520 operates on a 7.4 V 3000 mAh lithium-ion battery providing more than eight hours of continuous operation, and includes rugged coaxial two-pole Kelvin test pins with a remote SAVE button for efficient field testing. It is ideal for maintenance, troubleshooting, and performance testing of individual stationary batteries, with data logging capabilities and compatibility with Fluke Battery Management software for trend analysis and report generation.