A modern receiver-in-canal hearing aid uses a 25–100 mAh rechargeable coin cell, recharges nightly, runs 14–18 hours a day at near-zero average current with brief audio bursts, lives in a humid ear canal, and has to last at least three years on a battery you can''t replace. There is essentially no consumer-electronics cell on earth with stricter requirements.

The hearing-aid coin cell, deconstructed

The category is dominated by Ø 5–10 mm coin cells in the LIR / ML steel-shell family. They use:

  • A dual-shell hermetic crimp with a fluoropolymer gasket — three orders of magnitude better humidity resistance than a pouch laminate.
  • Welded pin contacts instead of tabs, so the cell drops directly into a metal contact spring on the device.
  • Conservative voltage windows (3.0–4.1 V on LIR variants) to extend cycle life past 1,000 cycles.
  • Ultra-low self-discharge electrolyte (sub-2 % per month) so a 60 % SOC cell still has charge two months later when the device sits on a shelf.

The lessons that travel

If you are building any of:

  • A continuous-glucose monitor patch (14-day life, sterile pack).
  • A smart ring or skin-contact biosensor.
  • An implantable pulse generator.
  • A long-life industrial sensor with sealed enclosure.

Hearing-aid manufacturing IP is the most relevant template. Specifically: hermetic crimp design, dual-shell construction, pin-contact terminations, low-SD electrolyte, and ISO 13485-aligned production.

What we ship into hearing-aid programs today

The two most common Zufek SKUs in this category:

  • LIR ZA10 (10 mm Ø, 30 mAh) for in-ear receiver-in-canal devices. 1,000+ cycles at 0.2 C.
  • LIR ZA13 (8 mm Ø, 25 mAh) for completely-in-canal devices. 800+ cycles, slimmer crimp.

Both run on our medical-grade line under ISO 13485 alignment, with full lot traceability and IEC 62133-2 / IEC 60086-4 documentation per shipment.

If you''re evaluating a coin-cell vendor for a wearable

Three diligence questions worth asking:

  1. Show me your hermetic-crimp leak test data on a 12-month shelf-life sample.
  2. Show me the pin-contact pull-test SOP and the AQL.
  3. Can you document a 14-day continuous-discharge profile at body temperature with full capacity reporting?

If they can answer all three quickly, they have shipped this category. If they can''t, your medical timeline is at risk.