An Integrated Mixed-Signal Current Conditioning System for Li-Po Batteries Lifespan Improvement

Lithium-ion batteries are one of the most widespread solutions for what concerns energy storage solutions, due to their high energy density, low self-discharge rate, and efficiency in both portable electronics and larger applications like electric vehicles and renewable energy systems. Their ability to store large amounts of energy in compact forms has revolutionized a wide range of industries, enabling significant advancements in technology. However, despite their widespread adoption, Li-ion batteries are subject to degradation over time, influenced by factors such as temperature, discharge current profiles and external environmental factors. A specific subset of these batteries, lithium-ion polymer batteries, has emerged as a popular choice for applications where weight, form factor, and flexibility are critical, such as in drones, mobile devices, and wearable electronics. As most lithium-ion batteries, they too face degradation challenges, particularly when exposed to varying current profiles. This work investigates the degradation effects in Li-Po batteries, specifically focusing on how different pulsed current widths impact their lifespan, under same average current conditions. For this purpose some test batteries (GREPOW - GRP170723 & GRP200721) have been monitored during several charge/discharge cycles trying to understand how their performances are affected by the different pulsed discharge currents. The measurements have been conducted with a custom PCB along with a suitable data acquisition system. In response to the obtained results, a current conditioning system was developed to shape the current profile in order to improve the lifespan of Li-Po batteries. The entire system is composed by three main sub-blocks: a current sensing circuit, a moving average block and a current limiter. The current sensing block is responsible for continuously monitoring the current flow through the battery. This information is then sent to the moving average block which is designed to process the sensed current data calculating an averaged value over a set time interval. If the average current is higher than a fixed threshold value, the last block of the circuit is activated. The current limiter should ideally ensure that momentary spikes do not affect the lifespan battery and that the overall current remains within safe limits by regulating the gate voltage of the main MOS device.