# US 2008/0187802 A1 · Ptc element as a self regulating start resistor for a fuel cell stack > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0187802 A1 - Document ID: US20080187802A1 - Status: Published application - Kind: A1 - Application number: 11/549,737 - Filed: 2006-10-16 - Published: 2008-08-07 - Earliest claimed: 2006-10-16 - Assignees: GM Global Technology Operations LLC - Inventors: Benno Andreas-Schott; Glenn W. Skala; Jeffrey A. Rock; Balsu Lakshmanan; Robert S. Foley; Michael W. Murphy - Web page: https://patentgrep.com/patent/US20080187802A1 ## CPC - H01M 8/0432: Temperature; Ambient temperature - H01M 8/04223: during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells - H01M 8/04225: during start-up - H01M 8/0488: {of fuel cell stacks} - Y02E 60/50: Fuel cells - H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract At least one positive temperature coefficient element is used to efficiently control fuel cell voltage at startup and shutdown making the fuel cell more efficient and protecting the electro catalyst layer. ## Claims ### Claim 1 A fuel cell comprising: at least a pair of spaced apart plates; a membrane positioned between said plates; and a positive temperature coefficient element electrically connected between said plates, whereby during startup of the fuel cell said element limits a voltage generated by the fuel cell until the fuel cell has reached a normal operating temperature. ### Claim 2 (depends on 1) The fuel cell according to claim 1 wherein said element is positioned at a coolant outlet of the fuel cell and is electrically connected between a positive terminal and a negative terminal of the fuel cell. ### Claim 3 (depends on 1) The fuel cell according to claim 1 wherein said element is positioned in an opening formed in said membrane and is electrically connected between said at least one pair of plates. ### Claim 4 (depends on 3) The fuel cell according to claim 3 wherein said element is bonded to one of said plates. ### Claim 5 (depends on 3) The fuel cell according to claim 3 including a spring positioned in said opening between said element and one of said plates. ### Claim 6 (depends on 1) The fuel cell according to claim 1 wherein said element has a contact area with said plates of less than 100 square millimeters. ### Claim 7 (depends on 1) The fuel cell according to claim 1 wherein said element is formed of screen printed ink. ### Claim 8 (depends on 1) The fuel cell according to claim 1 wherein the fuel cell includes a plurality of said plates arranged in a stack, one of said membranes positioned between each adjacent pair of said plates and one of said elements connected between said plates of each adjacent pair of plates. ### Claim 9 (depends on 7) The fuel cell according to claim 7 wherein said elements are staggered on adjacent ones of said membranes. ### Claim 10 (depends on 1) The fuel cell according to claim 1 wherein said element is in a range of 20 to 40 microns thick. ### Claim 11 (depends on 1) The fuel cell according to claim 1 wherein said element is a silicon controlled rectifier[RF3]. ### Claim 12 A fuel cell comprising: a plurality of bipolar plates arranged in a stack between a positive terminal and a negative terminal; a plurality of membranes, each said membrane positioned between an associated pair of adjacent ones of said plates; and a positive temperature coefficient voltage limiting means electrically connected to said stack, whereby during startup of the fuel cell said limiting means limits a voltage generated by the fuel cell until the fuel cell has reached a normal operating temperature. ### Claim 13 (depends on 12) The fuel cell according to claim 12 wherein said limiting means is a single positive temperature coefficient element positioned at a coolant outlet of the fuel cell and is electrically connected between said positive terminal and said negative terminal. ### Claim 14 (depends on 12) The fuel cell according to claim 12 wherein said limiting means includes a plurality of positive temperature coefficient elements each positioned in an opening formed in one of said membranes and electrically connected between said associated pair of plates. ### Claim 15 (depends on 14) The fuel cell according to claim 14 wherein each said element is bonded to one of said associated plates and including a spring positioned in said opening between said element and another one of said associated plates. ### Claim 16 (depends on 14) The fuel cell according to claim 14 wherein said elements are staggered on adjacent ones of said membranes. ### Claim 17 A fuel cell comprising: a plurality of bipolar plates arranged in a stack between a positive terminal and a negative terminal; a plurality of membranes, each said membrane positioned between an associated pair of adjacent ones of said plates; and a plurality of positive temperature coefficient elements, each of said element positioned in an opening formed in one of said membranes and electrically connected between said associated pair of plates, whereby during startup of the fuel cell said limiting means limits a voltage generated by the fuel cell until the fuel cell has reached a normal operating temperature. ### Claim 18 (depends on 17) The fuel cell according to claim 17 wherein each said element is bonded to one of said associated plates and including a spring positioned in said opening between said element and another one of said associated plates. ### Claim 19 (depends on 17) The fuel cell according to claim 17 wherein said elements are staggered on adjacent ones of said membranes. ### Claim 20 (depends on 17) The fuel cell according to claim 17 wherein said elements are in a range of 20 to 40 microns thick.