Recall that an integrated IoT device contains one or more sensors, communication, power storage, and a microcontroller, all preferably in a small enough footprint to be deployable in many locations. Usually, the largest of these is the power storage component. For the final device to have a small footprint, the power storage component must not only be small but also have a form factor compatible with the rest of the IoT device. Consider, for example, a postage-sized device powered by a cylindrical AA cell-type battery. The battery makes the device too bulky and perhaps difficult to deploy in many applications where blending with the background is essential.
This recognition of the value of a thin form factor initially led designers to use thin-film lithium-ion batteries for IoT applications. It was thought that the thin form factor and their significant energy storage capacity could potentially power the low-energy use IoT devices for 10 years or more. The trouble was that when deployed in the field, these batteries were not able to handle pulse power, whether for communication or for actuation.
Close to 95% of installs in the field fail because of this weakness of the battery (to handle pulse power). Several workarounds, such as upsizing the battery to allow for larger pulse loads, were tried to resolve this issue. The large pulse loads on the batteries, combined with the existing high/low temperatures in the field, also led to a reduction in battery life. The use of the battery also led to additional circuitry because care must be taken to limit current draw during discharge and current input during charging.
OptiXtal decided to attack this critical problem of powering IoT devices from a different angle. We already had a form factor energy storage device with a long life (20 years or so), which could handle much higher pulse currents. We required a simple circuit because we did not supercharge the supercapacitor from pulse currents during charge or discharge. The only two issues we needed to solve were: could we find a partner to design ultra-low power circuitry that consumed very little during standby? Could the Supercapacitor's supercapacitor be small enough to trickle charge it even in low light conditions (flux less than 50 lumens)?
