US 9,812,901 B2
Emergency lighting battery charger
Camille Descarries, Montreal (CA); and David Perreault, Laval (CA)
Assigned to Thomas & Betts International LLC, Wilmington, DE (US)
Filed by Thomas & Betts International, LLC, Wilmington, DE (US)
Filed on Nov. 13, 2015, as Appl. No. 14/940,748.
Claims priority of provisional application 62/081,875, filed on Nov. 19, 2014.
Prior Publication US 2016/0141915 A1, May 19, 2016
Int. Cl. H02J 9/06 (2006.01); H02J 7/04 (2006.01); H02J 7/00 (2006.01)
CPC H02J 9/065 (2013.01) [H02J 7/04 (2013.01); H02J 7/007 (2013.01); H02J 7/0073 (2013.01); H02J 2007/0037 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A power supply, comprising:
a rechargeable battery;
circuitry comprising a first circuit path that includes a first resistor connected in parallel with a second circuit path that includes a second resistor, wherein the second circuit path further includes a transistor connected in series with the second resistor, wherein the first circuit path supplies a first current for charging the rechargeable battery and wherein the second circuit path selectively supplies, via the transistor, a second current for charging the rechargeable battery; and
a controller configured to:
determine a failure in external input power to an external load,
determine an amount of time the rechargeable battery discharges to supply power to the external load between the failure of the input power to resumption of the input power,
if the amount of time is less than a threshold, turning on the transistor to cause both the first circuit path and the second circuit path to supply the first and the second current for charging the battery for a first charging period that is proportional to the amount of time, and turning off the transistor to cause only the first circuit path, and not the second circuit path, to supply the first current subsequent to an end of the first charging period, and
if the amount of time is greater than or equal to the threshold, turning on the transistor to cause the first circuit path and the second circuit path to supply the first and the second current for charging the battery for a second charging period.