Rechargeable lithium-ion batteries are widely used in today’s portable electronic devices; particularly those demanding either significant amounts of power or a heavy usage frequency. When designing with lithium-ion, safety should always be on the forefront of the design engineer’s mind to ensure that proper care is taken - especially during charging. Lithium-ion safety considerations frequently result in a battery that is specially chosen for the given application and is tightly integrated with the system. Making future changes to that system can then be challenging and time-consuming.
If this is the case, why would a designer consider changing the power source? More often than not, the reason for converting comes down to a need to reduce cost. This may be to drive increased margins, to be more competitive with substitutes, or to reach a new or expanded customer base at a much lower price point. Converting from rechargeable lithium-ion to a single-use primary battery can be an attractive place to reduce costs. In addition to the price of the battery itself, lithium-ion designs require sophisticated circuitry to closely monitor charging and discharging, which is unnecessary if primary batteries are used.
Costly redundant systems may have even been employed to intentionally over-design for safety. Aside from bill-of-material costs, additional shipping and labor costs may be required to process returns and repairs. In addition to any cost considerations, the power requirements for modern electronic components have continued to decrease, and the usage of an extreme low power microcontroller in applications that were previously well suited for a rechargeable solution may now enable a primary battery solution instead.
In general, primary batteries that are designed for single use offer some inherent advantages over rechargeable lithium-ion batteries in portable devices. For example, if the device is used often, widely available primary batteries can be quickly swapped out for fresh ones with minimal downtime. There is also no need for packing bulky accessories, such as