Batteries are often used to supply units that are autonomously powered, from utility meters to key fobs and IoT wearables. These applications often have peak power needs can only be met with a supercapacitor.
Supercapacitors deliver peak power to support batteries.
Applications that are autonomously powered must use an energy harvester and / or battery. Where primary batteries are used they need to be high energy and low self discharge for the unit to have a long life. Examples are Lithium Thionyl Chloride batteries, used to power utility meters for up to 15 years, and CR2032 batteries in car key fobs and wearables. Batteries, which store energy electrochemically, are limited by the rate of the chemical reaction for the power they can deliver. This is exacerbated at cold temperatures such as outdoors in a North American or European winter. A short peak power is required to transmit data. This limited power delivery manifests itself as relatively high internal impedance, Rbatt, e.g. a CR2032 will typically be ~5 – 10Ω, a 7.7Ah Lithium Thionyl Chloride battery has internal impedance ~4.5Ω. A GS230 1.2F CAP-XX supercapacitor has Equivalent Series Resistance (ESR) of 25mΩ. Placing this supercapacitor across the battery means the supercapacitor will deliver nearly all the peak current – the current will be split between the battery and supercapacitor as a ratio of 1/ESR:1/Rbatt, so with the Lithium Thionyl Chloride battery, the supercapacitor will deliver over 99% of the current. CAP-XX offers solutions if the inrush current to charge the supercapacitor needs to be limited.