Feature: Batteries


Figure 1: Neighbouring balancing


Figure 2: Single-pair balancing


Types of balancing in battery management systems


By Ulrich Lentz, Technology Field Applications Engineer, BMS, Arrow Electronics


I


n today’s world, the desire to electrify everything and pave the way for fossil-free fuels has focused attention on the efficiency and safety of battery management systems (BMS). These are found in batteries that use lithium as a chemical reactant and which tend to overheat or explode if incorrectly charged.


The core of these systems is balancing, a crucial process


that has a significant impact on the battery’s performance and life span. There must be a balance between battery cells and pack at all times, otherwise problems range from energy losses,


10 July/August 2024 www.electronicsworld.co.uk


There must be a balance between battery cells and pack at all times, otherwise problems range from energy losses, overloading and deep discharging, to potentially devastating damage


overloading and deep discharging, to potentially devastating damage. An unbalanced battery can also suffer from premature ageing, shorter life span and frequent shutdowns when the remaining energy in the cells is not precisely determined. Luckily, BMS balancing can help, of which there are several methods – from passive balancing to innovative active balancing. Active balancing is preferable when optimal precision,


fast reaction times, extended battery lifespan and high balancing current are required. This is a method particularly common in stationary setups, like energy storage systems for emergency power supplies. It’s a good option where space is not restricted and long battery life is of critical importance. Passive balancing is used in applications with lower


voltages and lower levels of available power, like e-bikes and e-scooters, for example. Despite the differences between the two methods, cost


pressures, lack of expertise, limited space and the need for simple implementation often dictate that only passive methods are used in reality.


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