# US 6,294,766 B1 · Battery cell bypass with pre-loaded compression action

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- Number: US 6,294,766 B1
- Document ID: US6294766B1
- Status: Granted
- Kind: B1
- Application number: 09/364,987
- Filed: 1999-07-31
- Granted: 2001-09-25
- Earliest claimed: 1999-07-31
- Assignees: Microsemi Corporation
- Inventors: Tracy A. Autry; Fernando C. Lynch; Don Mathes
- Web page: https://patentgrep.com/patent/US6294766B1

## CPC

- H02J 7/54: Passive balancing, e.g. using resistors or parallel MOSFETs
- H02J 7/60: including safety or protection arrangements
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY

## Abstract

A battery cell bypass protection technology for use with NiH2 (or other energy storage) cells on a spacecraft or other high reliability application. The device is a thermally activated switch, designed to bypass the current around a failed (open) or failing cell so that the other cells in the battery are unaffected. One unique aspect of the design is a “pre-loaded” compression action, solder shorting mechanism. Another unique aspect is that the construction employs series redundant heaters and blocking diodes in multi-chip packages. These unique aspects provide consistent and complete shorting to provide a low-resistance cell bypass in any orientation on earth (1g) or in orbit (0g). Another unique aspect is the use of non-lead-based solder that minimizes “creep” over time and temperature.

## Claims

### Claim 1

A battery cell bypass circuit assembly comprising a) a plurality of series-connected diodes; b) means for connecting said diodes in parallel with said cell; and c) a thermally activatable mechanism for bypassing current around the cell, in the event it should fail, said mechanism comprising:
a solder ingot fixed adjacent said diodes, so that the ingot will melt whenever cell failure causes said diodes to heat; and
compression means for confining the flow of melted solder within the diode contact area, so that bypass current flows through the solder, which solidifies to form a permanent solder bond.

### Claim 2 (depends on 1)

A battery cell bypass assembly as in claim 1 having multiple, series, redundant discharge and charge heaters (diodes) to ensure fail-safe operation.

### Claim 3 (depends on 1)

A battery cell bypass assembly as in claim 1 using a non-lead-based solder to minimize “creeping” under time, temperature, and pressure.

### Claim 4 (depends on 1)

An assembly as in claim 1 wherein said compression means for confining solder flow includes a spring.