Mining Contract: Methods to De-Energize Batteries
During a mine emergency involving a methane-contaminated atmosphere, the need may arise to selectively de-energize non-critical batteries to render them inert and safe. Engineering analyses and laboratory evaluations are needed of new technologies for emergency de-energizing of batteries intended for mine equipment.
Contract Status & Impact
This contract is ongoing.
Batteries present specific hazards during mine emergencies by virtue of the energy they contain and the fact that this energy could be released in a variety of ways to pose a methane ignition risk. A previous study identified such battery ignition hazards from past underground coal mine emergencies.
Batteries present specific hazards during mine emergencies by virtue of the energy they contain and the fact that this energy could be released in a variety of ways to pose a methane ignition risk. At this time, no technologies exist to de-energize smaller lithium-ion batteries or large lead-acid batteries to ensure they do not serve as an ignition source when an explosive atmosphere develops. The desired technology must be resistant to inadvertent triggering and be capable of both local and remote activation. It should also be free from sparking/arcing risk while being operational until the de-energizing protocol has been fully completed.
Under this contract, TIAX LLC is evaluating candidate technologies for de-energizing batteries that take into account factors that drive cost, performance, and ease of implementation. A range of design and circuit options for de-energizing systems have been explored and two architectures (single-load, multi-load) appropriate for testing of laboratory prototypes have been identified. Single-load architecture uses a latching relay switching element and a load element designed to be integrated with the battery and the equipment it powers to the greatest extent possible. Multi-load architecture uses a two-phase de-energizing sequence in which one circuit discharges the battery across its main terminals, removing the bulk of the resident energy, with cell-level loads subsequently completing the process to ensure that all cells are rendered intrinsically safe by bringing each cell to low voltage and permanently maintaining the voltage there.
The contractor has constructed a prototype of the single-load architecture designed to function with lithium-ion batteries, and a prototype of the multi-load architecture designed with an integrated lead-acid battery. With both prototypes completed, work is transitioning to a variety of tests to examine current handling, thermal performance, and time-to-de-energize metrics for both lithium-ion and lead-acid battery systems. The final report will provide detailed summaries of the evaluations, laboratory testing, and prototype demonstrations, as well as recommendations for the next steps toward commercialization.