Emergency lighting system

An emergency lighting system, comprising:

• battery charging circuitry to charge a rechargeable battery based on available input power;
• temperature factor determination circuitry configured to determine one or more temperature factors of the battery;
• wherein each temperature factor represents a power output performance of the battery for a selected range of temperatures;
• normalized output capacity determination circuitry configured to determine a normalized output capacity of the battery based on a selected test protocol conducted at a determined temperature and a selected one of the one or more temperature factors;
• and
• emergency power level control circuitry configured to detect a power outage of the input power and determine a temperature at the time of the power outage;
• select a temperature factor, from among the one or more temperature factors, based on the determined temperature at the time of the power outage;
• and determine an available output capacity (ACP) of the battery based on the normalized output capacity and the selected temperature factor;
• wherein the emergency power level control circuitry is further configured to determine:
• a first lighting protocol to deliver a power level equivalent to a full rated power (FRP) of the emergency power level control circuitry, the first lighting protocol being based on comparing the ACP to a first selected value;
• a second lighting protocol to deliver a reduced power level of the emergency power level control circuitry (Preduced), the second lighting protocol being based on determining if ACP is between the first selected value and a second selected value;
• and
• a third lighting protocol to deliver a foldback power level of the emergency power level control circuitry, the third lighting protocol being based on determining if ACP is less than the second selected value;
• wherein the foldback power has a first power level Preduced, where Preduced is less than FRP, delivered for a first time period, a second ramped down power level delivered for a ramp down time period tramp, and a third minimum power level Pmin delivered for a third time period;
• wherein the emergency power level control circuitry is configured to select from among the first, second or third lighting protocols based on the value of ACP;
• and
• wherein the normalized output capacity determination circuitry is further configured to determine a safety factor and modify the normalized output capacity using the safety factor;
• wherein the safety factor represents a weighting factor on the battery output capacity having a value less than 1.

A non-transitory storage device that includes machine-readable instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising:

• detect a power outage of input power being used to charge a rechargeable battery;
• determine an available output capacity (ACP) of the battery based on a normalized output capacity of the battery;
• and
• determine a lighting protocol to cause a controller to deliver a foldback power level to a lighting load coupled to the battery, based on full rated power (FRP) of the controller;
• the lighting protocol also being based on determining if ACP is less than a selected value;
• wherein the foldback power has a first power level Preduced, where Preduced is less than FRP, delivered for a first time period, a second ramped down power level delivered for a ramp down time period tramp, and a third minimum power level Pmin delivered for a third time period;
• determine one or more temperature factors of the battery;
• wherein each temperature factor represents an output capacity performance of the battery for each temperature;
• and
• determine ACP based on a selected temperature factor;
• determine the normalized output capacity of the battery based on a selected test protocol and a temperature factor correlated to the test temperature;
• determine ACP as ACP=normalized output capacity*selected temperature factor;
• and
• determine a safety factor and modify the normalized output capacity using the safety factor;
• wherein the safety factor represents a weighting factor on the battery output capacity having a value less than 1.