Can a Li-ion powerbank be charged and discharged simultaneously?

This question often sparks debate among enthusiasts, and the answer isn’t as straightforward as one might think.

At first glance, the notion of charging and discharging a battery simultaneously seems feasible. However, delving into the technicalities unveils a more nuanced reality.

Li-ion powerbank

In the realm of powerbanks, the distinction between a “battery” and a “power bank” is crucial. While a battery is a relatively simple component found within any power bank, the power bank itself comprises a complex assembly of multiple components and circuits.

Fundamentally, current flow through a battery is akin to water flow through a pipe-it can only move in one direction at a time. When a circuit allows current to flow in the battery’s natural direction, it discharges the battery. Conversely, if the circuit redirects external power to force current in the opposite direction, it charges the battery.

Some powerbanks are designed to draw power from an external source while simultaneously providing power to a device, such as a phone. However, this feature, known as pass-through charging, isn’t universally available across all powerbanks. It’s often an arbitrary decision made by the engineers during the design phase.

Whether a powerbank can both charge and discharge its internal battery simultaneously depends on various factors. If the external power source can supply more power than the device demands, the battery may charge. Conversely, if the device requires more power than the external source provides, the battery may discharge. In scenarios where power input and output are balanced, the battery’s charge status may remain unchanged.

However, charging and discharging a battery simultaneously through the same terminals isn’t physically feasible due to the nature of current flow. In such cases, the net current is zero, meaning the battery neither charges nor discharges-it simply channels power directly to the connected device.

While it’s technically possible to design circuits that facilitate both charging and discharging concurrently by incorporating multiple pathways, the battery still experiences either charging or discharging at any given moment.

Moreover, the complexity of Li-ion battery charging profiles adds another layer of consideration. Li-ion batteries undergo a constant current followed by constant voltage charge profile, which can introduce voltage fluctuations affecting circuit stability and battery health.

In practical terms, powerbank manufacturers often opt to disallow simultaneous charging and discharging to avoid potential complications and ensure optimal battery performance. This approach minimizes risks such as suboptimal charging profiles, confusion between charging and discharging states, and potential damage from self-charging loops.

In essence, while the concept of charging and discharging a battery simultaneously may seem plausible, the intricate interplay of circuitry, battery chemistry, and engineering considerations often dictates otherwise in the realm of powerbanks.