Specify the operating sequence
A useful runtime requirement describes what the device does during the test. A portable product may alternate between startup, active measurements, display activity, communications and standby. The power demand in each state can differ. Write the representative sequence with the device engineering team and identify the equipment and software version. If more than one usage pattern matters, define separate tests. An unqualified statement such as eight hours of battery life leaves too much room for different interpretations when a supplier proposes a pack.
Use an explicit energy estimate
For an illustrative engineering calculation, a device averaging 12W for three hours requires 36Wh at its load before reserve and losses. That example is not a recommendation for a medical application. The device team must determine the required reserve, applicable conditions and response to low available energy. Capacity planning should account for the approved operating range and the required performance at the planned replacement threshold. Ask the battery supplier to state the assumptions used for each proposed capacity and configuration.
Distinguish an estimate from an indication
A displayed battery percentage is an estimate of battery state, not a direct guarantee of minutes remaining. Its usefulness depends on the battery model, measurement system, operating history and load. Define what information the device needs and how that information will be validated. Check behavior during charging, after storage and near the expected end of discharge. The device manufacturer should decide how indications, warnings and operational decisions relate to the available data through its own design and risk-management process.
Plan for aging and service
The initial sample result is only one point in the product lifecycle. Define the service or replacement threshold and how the device or maintenance team will recognize it. Ask for relevant evidence on capacity retention under conditions related to the intended use. Keep cycle-life, calendar service duration and warranty conditions separate. If the battery can be replaced, control the approved replacement part and instructions. A compatible connector or nominal voltage should not be treated as approval to install a different battery model in service.
Validate within the complete product
Test the proposed pack in the actual device using the agreed sequence, charger and relevant environmental conditions. Record pack identity, specification revision, equipment version and measurement method. The responsible team should assess unexpected shutdown, power transitions and any required user indications. Keep the evidence specific to the evaluated configuration. Public battery product pages can help an early discussion, but they cannot establish runtime or clinical suitability for a finished medical device. Those conclusions require the device manufacturer's controlled evaluation and release process.
Sources & further reading
Prepared for the medical equipment battery projects collection. General engineering guidance does not replace a model-specific datasheet or application validation. Source review: 4 November 2026.