Lithium Ion Cell/Batteries Electromagnetic Field Reduction in Phones for Hearing Aid Compliance

The Hearing Aid Compatibility Act of 1988 (HAC Act) generally requires that the Federal Communications Commission (FCC) ensure that telephones manufactured or imported for use in the United States after August 1989, and all 'essential' telephones, are hearing aid-compatible. The electromagnetic field (EMF) emission is generated by electrical currents in the phones' circuit boards and components, including the battery. Here, we have investigated design changes to reduce the EMF from Lithium Ion (Li-ion) batteries. Changes mainly include: (1) Li-ion cell internal positive/negative tab location and length on cathode/anode layers; and (2) Li-ion cell external positive/negative connectors spacing. Results show that the cell's internal tab locations and spacing between the cell's external connectors play critical roles in reduction of battery EMF emissions. It is important that cells' design changes are compatible with the manufacturing processes.