Emergency lighting system
The present disclosure provides an emergency lighting system that includes battery charging circuitry to charge a rechargeable battery based on available AC power; and emergency power level control circuitry configured to detect a power outage of the AC power and determine an available output capacity (ACP) of the battery based on a normalized output capacity of the battery; the emergency power level control circuitry is further configured to determine a lighting protocol to deliver a foldback power level of the emergency power level control circuitry, the lighting protocol being based on determining if ACP is less than a selected value; wherein the foldback power having 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.
1 . An emergency lighting system, comprising:
battery charging circuitry to charge a rechargeable battery based on available input power;
emergency power level control circuitry configured to detect a power outage of the input power and determine an available output capacity (ACP) of the battery based on a normalized output capacity of the battery; the emergency power level control circuitry being further configured to determine a lighting protocol to deliver a foldback power level of the emergency power level control circuitry, the lighting protocol being based on determining if ACP is less than a first selected value; wherein the foldback power has a first power level Preduced, where Preduced is less than a full rated power (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;
temperature factor determination circuitry configured to determine one or more temperature factors of the battery; and
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;
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 a battery output capacity, having a value less than 1.
2 . The system of claim 1 ,
wherein each temperature factor represents a power output performance of the battery for a selected range of temperatures; and wherein the emergency power level control circuitry is further configured to determine ACP based on a selected temperature factor.
3 . The system of claim 2 , wherein the emergency power level control circuitry is further configured to determine ACP as ACP=normalized output capacity*selected temperature factor.
4 . The system of claim 1 , wherein the emergency power level control circuitry is further configured to determine another lighting protocol to deliver a power level equivalent to the FRP of the emergency power level control circuitry, based on comparing the ACP to a second selected value.
5 . The system of claim 1 , wherein the emergency power level control circuitry is further configured to determine another lighting protocol to deliver a reduced power level of the emergency power level control circuitry (Preduced), based on determining if ACP is between a second selected value and the first selected value.
6 . The system of claim 1 , wherein the FRP of the emergency power level control circuitry is based on a capacity of the battery and a requirement of a lighting load coupled to the emergency power level control circuitry and the battery.
7 . The system of claim 1 , wherein the emergency power level control circuitry is further configured to determine a foldback start time, tF, based on ACP and FRP;
wherein tF occurs at the end of the first time period.
8 . The system of claim 7 , wherein the ramp down time period is selected to minimize perceived changes in lighting; and wherein the emergency power level control circuitry is configured to ramp down power from Preduced to Pmin over the ramp down time period, starting at tF.
9 . The system of claim 1 , wherein the selected test protocol comprises operating the emergency power level control circuitry at FRP to deliver power to a lighting load for X minutes; operating the emergency power level control circuitry to deliver Pmin to the lighting load for Y minutes, where X≤Y; and increasing the power level of the emergency power level control circuitry to FRP for Z minutes, starting after Y minutes, until a low voltage disconnect event occurs; wherein the normalized output capacity determination circuitry is configured to determine a battery output capacity based on the power delivered during the X, Y and Z time periods; and wherein the normalized output capacity determination circuitry is configured to determine the normalized output capacity of the battery as: normalized output capacity=output capacity/selected temperature factor.
10 . 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.
11 . The system of claim 10 , wherein the FRP of the emergency power level control circuitry is based on a capacity of the battery and a requirement of a lighting load coupled to the emergency power level control circuitry and the battery.
12 . The system of claim 10 , wherein the emergency power level control circuitry is further configured to determine a foldback start time, tF, based on ACP and FRP; wherein tF occurs at the end of the first time period.
13 . The system of claim 10 , wherein the ramp down time period is selected to minimize perceived changes in lighting; and wherein the emergency power level control circuitry is further configured to ramp down power from Preduced to Pmin over the ramp down time period, starting at tF.
14 . The system of claim 10 , wherein the selected test protocol comprises operating the emergency power level control circuitry at FRP to deliver power to a lighting load for X minutes; operating the emergency power level control circuitry to deliver Pmin to the lighting load for Y minutes, where X≤Y; and increasing the power level of the emergency power level control circuitry to FRP for Z minutes, starting after Y minutes, until a low voltage disconnect event occurs; wherein the normalized output capacity determination circuitry is configured to determine a battery output capacity based on the power delivered during the X, Y and Z time periods; and wherein the normalized output capacity determination circuitry is configured to determine the normalized output capacity of the battery as: normalized output capacity=output capacity/selected temperature factor.
15 . 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.
16 . The non-transitory storage device of claim 15 , wherein the machine-readable instructions, when executed by one or more processors, cause the one or more processors to perform operations comprising:
determine another lighting protocol to deliver a power level equivalent to the FRP, based on comparing the ACP to a second selected value.
17 . The non-transitory storage device of claim 15 , wherein the machine-readable instructions, when executed by one or more processors, cause the one or more processors to perform operations comprising:
determine another lighting protocol to deliver a reduced power level of the emergency power level control circuitry (Preduced), based on determining if ACP is between a second selected value and the first selected value.
18 . The non-transitory storage device of claim 15 , wherein the FRP of the emergency power level control circuitry is based on a capacity of the battery and a requirement of a lighting load coupled to the emergency power level control circuitry and the battery.
19 . The non-transitory storage device of claim 15 , wherein the machine-readable instructions, when executed by one or more processors, cause the one or more processors to perform operations comprising:
determine a foldback start time, tF, based on ACP and FRP; wherein tF occurs at the end of the first time period.
20 . The non-transitory storage device of claim 15 , wherein the ramp down time period is selected to minimize perceived changes in lighting; and wherein power is ramped down from Preduced to Pmin over the ramp down time period, starting at tF.
21 . The non-transitory storage device of claim 15 , wherein the selected test protocol comprises operating the emergency power level control circuitry at FRP to deliver power to a lighting load for X minutes; operating the emergency power level control circuitry to deliver Pmin to the lighting load for Y minutes, where X≤Y; and increasing the power level of the emergency power level control circuitry to FRP for Z minutes, starting after Y minutes, until a low voltage disconnect event occurs; wherein the machine-readable instructions, when executed by one or more processors, cause the one or more processors to perform operations comprising:
determine a battery output capacity based on the power delivered during the X, Y and Z time periods; and
determine the normalized output capacity of the battery as: normalized output capacity=output capacity/selected temperature factor.