Custom Battery Solutions for Medical Devices

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Application Study for Small Medical Devices:

  • Portable Oxygen Concentrators
  • Infustion Pumps
  • Patient Monitors
  • Portable Ultrasound
  • Surgical Power Tools
  • CPAP
  • Other handheld, portable devices for patient care (non-life support or resuscitation)

Battery Design Requirementsfor Medical Devices

Designing a battery for a handheld medical device requires far more than achieving the customary voltage, capacity/runtime. Patient safety, performance and device reliability are paramount. Every small detail of the battery system must be engineered, tested, and documented to meet the stringent performance and regulatory requirements of a medical device.

The battery designer starts with a series of customer specifications.  For this specific medical device and battery, we have the following known items (but not inclusive):
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  • Battery Chemistry, Li Ion
  • Operating power of 6.0-8.4VDC, 500 mah nominal and 1200 mah peak for 3 seconds
  • Runtime, complete shift of 8 hours, energy needs of 14 Wh
  • Cycle life of 500 cycles, slated usage of 18-24 months
  • Charge in a multibay charge rack
  • Operating temperature of 0-35C degrees
  • IP 45
  • Vibration and shock; typical drop from table height 6X, no interference with usage or internal exposure, normal transport vibration scheme
  • BMS with fuel gauge, acccuracy to 3-5%, 5 visual LEDS, serial communications protocol
  • Gold plated output spade connector
  • Custom molded housing, tamper proof
  • Certifications per UN 38.3, UL2054, IEC 606001-1, IEC 62133


Using these specifications,we begin our design process.  However; our priority in the design is patient safety. The battery must be designed to minimize the risk of overheating, fire, electrolyte leakage, or electrical failure. Key elements are:
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  • Proper cell selection
  • Robust battery management electronics
  • Multiple layers of short circuit protection between polarities
  • Mechanical design that prevents damage during normal use or accidental abuse
  • Engineered plastics materials meeting UL V0 flammability
  • Seal all openings to prevent ingress of dust and water

Reliability is equally critical. Medical devices may operate continuously and/or are expected to function immediately in any emergency. The battery must provide consistent and reliable capacity throughout its service life.  The battery must maintain stable voltage under varying current loads.  It must deliver predictable and stable performance over many charge and discharge cycles.
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A well-designed Battery Management System (BMS) is essential in batteries powering medical devices. Key elements for the BMS are:
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  • Over voltage protection, undervoltage protection, overcurrent protection and redundancy (mechanical or electronic fuse)
  • Serial communications protocol, two wire and one wire systems
  • Being a two cell battery, cell balancing not needed. Assemble the battery with matched cells (voltage and impedance)
  • Off the shelf TI or Maxim IC for fuel measurements


Medical batteries must perform across a wide range of environmental conditions. Plastics used must have ability to resist cleaning with alcohol or other chemicals.  Choose an industrial ABS/PVC blend with high heat tolerance, good stability, resistant to chemicals, high impact material.  High impact plastics are needed to meet impact drops of 6 sides x 4 at 6 feet height onto tile floor.

A good practice is use of gold plating for mechanical and electrical battery interface. Medical devices are used in wet conditions where corrosion/electrolysis may occur. Gold plated terminals (15 micron thickness) are required.

Battery must fit properly on the medical device. Connector and slide/latch detail must be secure, reliable, and designed to prevent incorrect installation or accidental disconnection and never disconnect during usage of the battery and device.

Regulatory compliance must be designed into the product.  One cannot rely on passing certifications if the requirements are not designed into the battery at the onset.  Consider how the battery may be short circuited, testing at altitude, low and high vibration frequencies, overcharged, over discharged. The targeted certifications for UN38.3, UL 2054, IEC60601 and UL62133 all require such testing as a battery. Of course, the basic building block, the cell must also have its own certifications for safety before any product certification can be performed. 

With all the certifications comes comprehensive documentation, risk analysis and validation testing. Keep design records throughout each test and verification.  Keep records of every component (supplier, batch, IQC) within the battery design for traceability afterwards. AMP manufacturing meets or exceeds ISO 13485 requirements for Medical Device Quality Management System.

Finally, battery designers must consider the entire product lifecycle. Sourcing of high-quality cells from reputable suppliers, maintaining production traceability, validating manufacturing processes, field serviceability, and ensuring long-term component availability are all extremely important and on the battery engineer's radar. A carefully engineered battery system will operate properly within the medical arena.  A poorly designed battery will always be a weak link in the chain and un doubtedly result in field returns, user downtime, higher costs and possible fire and explosions in the medical arena.

AMP combines safety, reliability, intelligent electronics, regulatory compliance, and robust mechanical engineering into every medical battery. It behaves as a single integrated system with that medical device which healthcare professionals need and trust.

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