Detecting thermal events in battery packs
A battery module for use in a battery pack is disclosed. The battery module ( 12, 12 ′) comprises a plurality of battery cells ( 24, 25 ) and a sensing circuit ( 62 ) extending across the battery cells. A monitoring unit ( 46 ) is connected to the sensing circuit. The monitoring unit comprises a continuity detector ( 66 ) arranged to detect a break in continuity of the sensing circuit ( 62 ). This can allow a thermal event occurring in one of the plurality of cells to be detected.
1. A battery module comprising:
a plurality of battery cells;
a sensing circuit extending across the plurality of battery cells, the sensing circuit comprising a continuous severable component; and
a monitoring unit connected to the sensing circuit,
wherein the monitoring unit comprises a continuity detector arranged to detect a break in continuity of the continuous severable component, and
the continuous severable component comprises a trace on a circuit board.
2. A battery module according to claim 1 , wherein the monitoring unit is arranged to produce an alarm signal when a break in continuity of the continuous severable component is detected.
3. A battery module according to claim 1 , wherein the continuous severable component extends across a vent path of each of the plurality of battery cells.
4. A battery module according to claim 1 , wherein the continuous severable component is arranged to be severed by a venting action of a cell undergoing a thermal event.
5. A battery module according to claim 1 , wherein the continuous severable component is an electrical conductor.
6. A battery module according to claim 5 , wherein the monitoring unit is arranged to apply an electrical signal to the electrical conductor, and to detect an open circuit in the electrical conductor.
7. A battery module according to claim 1 , wherein the circuit board comprises a plurality of vent holes, each vent hole associated with a battery cell, and the continuous trace spans a plurality of vent holes.
8. A battery module according to claim 1 , wherein the trace includes a stress concentration feature where it spans a vent hole.
9. A battery module according to claim 8 wherein the stress concentration feature comprises at least one notch in the trace.
10. A battery module according to claim 1 , further comprising a laminated busbar, wherein the circuit board is part of the laminated busbar.
11. A battery module according to claim 1 , wherein the circuit board is arranged to bring electrical signals from the battery cells to a battery management unit.
12. A battery module according to claim 1 , wherein the monitoring unit is part of a battery management unit.
13. A battery module according to claim 1 , wherein the monitoring unit is arranged to receive an input from at least one other sensor.
14. A battery module according to claim 1 , the battery module comprising a plurality of sensing circuits.
15. A battery module according to claim 1 , wherein the plurality of battery cells are stacked, and each cell is orientated such that a vent path is in a direction of the sensing circuit.
16. A method of detecting a thermal event in a battery module comprising a plurality of battery cells, the method comprising:
monitoring a sensing circuit, the sensing circuit comprising a continuous severable component extending across the plurality of battery cells;
detecting a break in continuity of the continuous severable component; and
producing an alarm signal when a break in continuity of the continuous severable component is detected,
wherein the continuous severable component comprises a trace on a circuit board.
17. A battery pack comprising:
a plurality of battery cells;
a sensing circuit extending across the plurality of battery cells, the sensing circuit comprising a continuous severable component; and
a monitoring unit connected to the sensing circuit,
wherein the monitoring unit comprises a continuity detector arranged to detect a break in continuity of the continuous severable component, and the continuous severable component comprises a trace on a circuit board.