# US 4,397,918 A · Fuel cell stack shorting method and apparatus

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- Number: US 4,397,918 A
- Document ID: US4397918A
- Status: Granted
- Kind: A
- Application number: 06/366,659
- Filed: 1982-04-08
- Granted: 1983-08-09
- Earliest claimed: 1982-04-08
- Assignees: Energy Research Corporation
- Inventors: Chang V. Chi
- Web page: https://patentgrep.com/patent/US4397918A

## CPC

- H01M 8/04014: Heat exchange using gaseous fluids; Heat exchange by combustion of reactants
- H01M 8/0267: having heating or cooling means, e.g. heaters or coolant flow channels
- H01M 8/04074: {Heat exchange unit structures specially adapted for fuel cell}
- H01M 8/04246: {Short circuiting means for defective fuel cells (detection of defective fuel cells H01M8/04664, methods for shunting fuel cells H01M8/04955)}
- H01M 8/2484: characterised by external manifolds
- H01M 8/04671: {of the individual fuel cell}
- H01M 8/04679: {of fuel cell stacks}
- H01M 8/04768: {of the coolant}
- H01M 8/249: comprising two or more groupings of fuel cells, e.g. modular assemblies
- 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

Electrical conductive means is used to connect first and second cooling assemblies of a fuel cell stack to thereby establish a short circuit path which bypasses the fuel cells situated between these cooling assemblies

## Claims

### Claim 1

A fuel cell stack comprising:
a plurality of cooling assemblies;
a number of fuel cells situated between successive of said cooling assemblies;
and conductive means connecting first and second of said cooling assemblies establishing a short circuit path which electrically bypasses the fuel cells situated between said first and second cooling assemblies.

### Claim 2 (depends on 1)

A fuel cell stack in accordance with claim 1 wherein:
said connecting means comprises one or more conductive members.

### Claim 3 (depends on 2)

A fuel cell stack in accordance with claim 2 wherein:
said first and second cooling assemblies each have a plurality of passages therethrough for carrying a cooling gas;
and each of said conductive members has one end extending into and along a first end of a difference passage of said first cooling assembly and another end extending into and along a first end of a different passage of said second cooling assembly.

### Claim 4 (depends on 3)

A fuel cell stack in accordance with claim 3 wherein:
the passages of said first cooling assembly into which said conductive members extend and the passages of said second cooling assembly into which said conductive members extend are selected to reduce cooling of said stack by the amount of cooling required to cool said cells between said first and second cooling means.

### Claim 5 (depends on 4)

A fuel cell stack in accordance with claim 4 wherein:
each of said fuel cells has process gas channels for carrying oxidant and fuel process gases;
and said stack further includes means for closing the process gas channels of the fuels cells situated between said first and second cooling assemblies.

### Claim 6 (depends on 3, 4)

A fuel cell stack in accordance with claim 3 or 4 wherein:
the passages of said first cooling assembly into which said conductive members extend and the passages of said second cooling assembly into which said conductive members extend are selected to promote uniform current distribution in said first and second cooling assemblies.

### Claim 7 (depends on 3)

A fuel cell stack in accordance with claim 3 wherein:
said passages of said first cooling assembly are arranged in succession;
said passages of said second cooling assembly are arranged in succession;
alternate ones of said passages of said first cooling assembly have conductive members extending therein;
and alternate ones of said passages of said second cooling assembly have conductive members extending therein.

### Claim 8 (depends on 1)

A fuel cell stack in accordance with claim 1 wherein:
said first and second cooling assemblies each have one or more passages therethrough for carrying a cooling gas;
and a first conductive member has one end extending into a first end of a first passage of said first cooling assembly and another end extending into a first end of a first passage of said second cooling assembly.

### Claim 9 (depends on 8)

A fuel cell stack in accordance with claim 8 wherein:
a second conductive member has one end extending into a second end of said first passage of said first cooling assembly and another end extending into a second end of said first passage of said second cooling assembly.

### Claim 10 (depends on 8, 9)

A fuel cell stack in accordance with claim 8 or 9 wherein:
the section of each said conductive members exterior of said first and second passages includes a coating for electrically insulating said section from the fuel cells situated between said first and second cooling assemblies and for protecting said section from the corrosive components associated with said fuel cells.

### Claim 11 (depends on 10)

A fuel cell stack in accordance with claim 10 further comprising:
means for closing the open area of the first and second ends of said first passage and the open area of the first and second ends of said second passage with a material resistant to the corrosive components of said fuel cells.

### Claim 12 (depends on 10)

A fuel cell stack in accordance with claim 10 wherein:
said conductive members each include a plurality of conductive strands and the cross-section of said strands is less than the cross-section of the passage ends into which said conductive strands extend.

### Claim 13 (depends on 12)

A fuel cell stack in accordance with claim 12 wherein:
said strands of each conductive member extending into a passage are corrugated.

### Claim 14

A method of shorting a fuel cell stack of the type comprising a plurality of cooling assemblies between successive ones of which are situated a number of fuel cells, the method comprising:
connecting a conductive means to a first cooling assembly;
and connecting said conductive means to a second cooling assembly;
whereby a short circuit path is established which electrically bypasses the fuel cells situated between said first and second cooling assemblies.

### Claim 15 (depends on 14)

A method in accordance with claim 14 wherein:
said connecting steps include inserting one end of a conductive member into a passage in said first cooling assembly and inserting the other end of said conductive member into a passage in said second cooling assembly.

### Claim 16 (depends on 15)

A method in accordance with claim 15 wherein said connecting steps further include:
inserting first ends of further conductive members in further passages of said first cooling assembly and inserting second ends of said further conductive members into further passages in said second cooling assembly.

### Claim 17 (depends on 16)

A method in accordance with claim 16 wherein:
the passages of said first and second cooling assemblies into which conductive members are inserted are selected to reduce cooling of said stack by the amount of cooling required to cool said cells between said first and second cooling assemblies.

### Claim 18 (depends on 17)

A method in accordance with claim 17 further comprising:
closing the process gas channels of said cells situated between said first and second cooling assemblies.

### Claim 19 (depends on 15, 16)

A method in accordance with claim 15 or 16 wherein:
said inserting steps result in said ends of said conductive members extending maximally into said passages.

### Claim 20 (depends on 15, 16)

A method in accordance with claim 15 or 16 wherein:
said inserting steps result in the conductive strands of said conductive members within said passages becoming corrugated.

### Claim 21 (depends on 15, 16)

A method in accordance with claim 15 or 16 wherein:
said conductive members exterior of said passages include a coating for electrically insulating said conductors from the fuel cells situated between said first and second cooling assemblies and for protecting said conductors from the corrosive components of said fuel cells.

### Claim 22 (depends on 21)

A method in accordance with claim 21 further comprising:
plugging the ends of said passages into which conductive members are inserted with a material resistant to the corrosive components of said cells.

### Claim 23 (depends on 16)

A method in accordance with claim 16 wherein:
the passages of said first and second cooling assemblies into which said conductive members extend are selected to promote uniform current distribution in said first and second cooling assemblies.

### Claim 24 (depends on 16)

A method in accordance with claim 16 wherein:
said passages of said first cooling assembly into which said conductive members are inserted are alternate passages of said first cooling assembly;
and said passages of said second cooling assembly into which said conductive members are inserted are alternate passages of said second cooling system.