Although EVs are gaining acceptance, many consumers have lingering fears over the safety of lithium-ion batteries after a crash. These people may find comfort in a patent filing from Tesla, which hints the company is looking to bolster battery safety with a special “pyrotechnic disconnect” device.
According to the patent, a “pyrotechnic disconnect” can sever the electrical connection between a battery pack and a motor, increasing the safety of the electrical system. In demanding situations, the disconnect must interrupt very large currents, but doing so can create electric arcs that need to be suppressed in order to avoid further hazards. It’s important these electric arcs are managed properly without making the disconnect overly complex or expensive to implement, a challenge which Tesla’s system hopes to overcome.
Tesla’s device includes a housing with a combustion chamber inside, in addition to a pyrotechnic charge in that combustion chamber. A busbar covers the opening of the combustion chamber and is configured to be severed by activation of the pyrotechnic charge. Importantly, the pyrotechnic charge is configured so that gas cools those pesky electric arcs. There’s an exhaust port in a grating in a wall of the housing that allows gas to suppress the electric arc formed by the severing of the busbar. Arc splitter plates arranged in the housing help suppress an arc by dividing it into multiple arcs, interrupting the current flow.