Coin cells and peak current draw

Designers of portable equipment using coin cell batteries are challenged by system level energy budget considerations, mainly driven by MCU and RF current consumption, as well as by the capacity and specification limits battery manufacturers provide. This report shows that adding a capacitor in parallel with a CR2032 coin cell is the most effective choice a designer can make to maximize battery capacity utilization in low power RF applications (more than 40% improvement with poor quality CR2032s). The test results also show that using 30mA peak current versus 15mA peak current only slightly reduce the effective capacity of a CR2032 (9% on average depending on vendor). These observations are valid across all six coin cell vendors tested, and implies that minimizing average current is the key to achieving long battery life with CR2032s.