The Firetrol FTA1100‑AA is a combined automatic and manual diesel engine fire pump controller that includes an integrated four‑stage battery charger for 12 V or 24 V negative‑ground lead‑acid or Ni‑Cd batteries. Common failure modes reported for this model are: (1) the qualification stage LEDs remain flashing or fail to change, indicating a fault in the battery acceptance check circuitry; (2) the charger fails to advance to subsequent stages, often due to a defective charging relay or control IC; and (3) the controller may display “Battery Fault” or similar error codes when the battery voltage drops below the minimum threshold. First‑check diagnostics should include verifying that the input supply is within spec (12/24 V negative ground), inspecting the charger’s output terminals for proper voltage during each stage, and reviewing the controller’s diagnostic LED pattern or error log to pinpoint which charging step is stalled.[oss-gpt-20b]