Tech/Software

Knowhow: what is a battery management system?

battery management system

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This guide outlines what a battery management system (BMS) is, what it can do, and the future of battery management system design.

The BMS has become a crucial tool in the global battle against polution and also climate change, being most effectively employed in electric vehicles as well as other battery-powered devices and equipment, plus their growing use as a source of household power in many areas.

Motor vehicles particularly have made a huge contribution in the amount of pollutants present in the air. And, in this way, the interest in the use of electric vehicles has been gaining space more and more in the sense of replacing conventional vehicles in the near future.

Electric vehicles are those where the propulsion system is provided by an electric motor powered by an energy storage system, which can be formed by a set of batteries only, or by a set of batteries connected to supercapacitors. The use of supercapacitors together with the battery pack is intended to store the energy peaks from the braking, conditioning this energy so that it can be stored in the battery pack or used by the electric motor.

For example, in an electric vehicle model with two electric motors, each coupled to the front wheels, the battery management system between the set of batteries and supercapacitors can be developed in order to increase the battery autonomy without causing damage to vehicle performance. For the development of the battery management system, fuzzy logic can be used with the resulting improvement of the vehicle’s autonomy.

As the world moves further towards advancing this technology, sophisticated design from custom hardware and software development companies like Integra Sources will help further improve the functionality and effectiveness of these systems.

Benefits of a battery management system

In general, we can say that a battery management system allows the increase of the battery pack’s useful life, or rather, allows the number of recharges normally announced for each type of battery (lithium, lead acid) to be reached, with impacts relatively reduced battery performance and efficiency. In short, the BMS makes it possible to maintain the quality of the batteries at high levels for a longer period of time and, therefore, to avoid severe wear or misuse of the batteries. Let’s see below what a battery management system does, in simple terms.

Monitoring

The battery management system allows you to effectively control the status of the battery(ies), monitoring its voltage, temperature, state of charge, refrigerant flow, current, and other variables. In this way, there is a constant check of the health status of the electric vehicle batteries.
If the vehicle is equipped with a regenerative braking system , the BMS will control battery charging by redirecting the energy recovered from braking or engine deceleration, used to recharge the batteries.

Calculation of indicators

The battery management system can also calculate relevant indicators based on the variables mentioned above, namely: maximum load current with a load current limit, maximum discharge current with a discharge current limit (DCL), energy delivered from the last recharge, total energy delivered since first use, total operating time since first use, etc.

Communication of relevant data

The battery management system also allows the reporting of all the data mentioned above to an external device, using various wired or wireless communication channels.

Protection

The battery management system protects the batteries by preventing:
– over current,
– over voltage (during charging),
– under voltage (during discharge), especially important for lead-acid and cell-ion batteries
– excessive temperatures
– under temperatures
– excess pressure (NiMH batteries)

Optmization

The battery management system can guarantee that all the cells that make up the batteries are kept in the same state of charge, through their balancing, which allows to increase their useful life. Typically, individual cells in a battery can be at different levels of charge (SOC). If there is no redistribution, the discharge must stop when the cell with the lowest capacity is “empty”. Without balance, the cell with the lowest capacity is the weakest link, which can easily be overworked or underloaded, while the remaining cells with higher capacity are only partially cycled. In this way, there is a more accentuated wear of the batteries, with an impact on vehicle performance and battery life. In summary, the battery management system is recommended.

The future of battery management system design

General Motors has announced that it would be the first automaker to use a “virtually wireless” battery management system (BMS) in its future electric cars. According to the automaker, the system, will be a key part of its goal of powering various types of electric cars with a common set of batteries and associated components.

Called wBMS (Wireless Battery Management System), the system will allow electric vehicles to reach the market faster, as it will not be necessary to develop different communication protocols or wiring schemes for each vehicle.

The function of wBMS is to balance the load of the various modules that make up the batteries so that they have maximum performance, in addition to monitoring in real time various parameters and sensors to ensure their safe operation, increasing their useful life. Using wBMS reduces wiring in a battery by up to 90%, according to GM, which results in lighter vehicles and room for more cells, increasing capacity.

According to the automaker, wBMS also facilitates the reuse of batteries when they reach the end of their useful life in a vehicle, but still have enough capacity for, for example, use in solar energy storage systems in a home. Current BMS have to be re-engineered before the batteries can be reused.

“Scalability and complexity reduction is a theme of our batteries, and wBMS is a critical component in enabling this incredible flexibility,” said Kent Helfrich, executive director of Global Electrification and Battery Systems at GM. “The wireless system represents the epitome of Ultium’s configurability and should help GM produce profitable electric vehicles at scale.”

Summary

In a nutshell, a BMS will allow an electric vehicle or similar battery powered equipment to perform better, more economically and provide better system feedback than without one. Thus even when it comes down to less expensive items like electric scooters, the small extra cost in purchasing one with a BMS (rather than one without a BMS) is more than compensated by the advantages it brings to the item’s operation and longevity.

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