What's new with battery management systems (BMS) for electric vehicles?
Demands are increasing for efficient EVs, especially in regards to what's referred to as "range anxiety"—that is, the fear that an EV will run out of charge before it can reach another charging station. In order to assuage this issue, automotive companies are continuously investing in more efficient motors, innovative EV battery chemistries, and more advanced battery management systems.
Let's take a look at some recent examples of engineers tackling these problems facing EV battery systems.
What Does a Battery Management System Do?
First, a quick note on what an EV battery management system is. Most, if not all, Li-ion-based batteries include advanced battery management systems to ensure their proper use and safety. So what does a BMS monitor?
For a typical EV system, you can expect a BMS to do the following:
- Read the total voltage
- Read the current from/to the battery
- Read the temperature
- Determine the total charge
- Determine the battery health (by comparing the current capacity against the original capacity)
- Correctly manage regenerative breaking to recharge the batteries
- Detect over current situations
- Detect over-voltage situations
- Detect under-voltage situations
- Detect over-temperature situations
- Detect over-pressure (this is important if the battery starts producing hydrogen)
Since the EV battery management industry is critical to efficient car design, as well as safety, it is no doubt one of the key focus areas for EV manufacturing.
So, what have companies been up to lately and how are they hoping to change the EV industry?
Algorithm-Designed Efficiency: Bosch's Cloud-Connected Batteries
In July, Bosch announced a program that would allow EV batteries to be connected via the cloud for better maintenance. The software service enables "swam intelligence" via smart algorithms to monitor batteries in EV systems.
The idea is to bring the Internet of Things to automotive vehicles and by collecting large amounts of data from batteries to better understand efficiencies and failure points. Bosch, in turn, projects that they will be able to help reduce wear and tear on batteries by up to 20%. They could even prompt drivers with suggestions on how they can extend the life of their batteries.
Image from Bosch
The use of machine learning also gives way to better prediction systems so instead of simply monitoring the battery as it current stands, a system can predict how the battery is going to behave. In an environment where battery failures can result in a total disaster, battery prediction is something that will drastically improve the safety of Li-Ion batteries in EV environments. Data that Bosch will be using include the number of charge cycles, stress from acceleration and deceleration, and temperature.
Bosch has long been a manufacturer of components, especially IMU (inertial measurement units) andposition-tracking sensors that have served drones and robotics. The new EV battery-in-the-cloud system, however, is somewhat unique in their repertoire.
High-End Electrification: Lotus Unveils New Electric Vehicle
Also in July, British automotive company Lotus Cars unveiled their latest hypercar (i.e., concept car), the Evija, which they claim is "the first British all-electric hypercar."
The Lotus Evija is presented for the first time. Image from Lotus Cars
Lotus reports that the Evija has a top speed of 200mph, 0 to 60 in three seconds, and a target power output of 2,000ps—something they assert makes it the "most powerful car ever to enter production."
While these are impressive for any car, the real magic is in the power system with the use of a 2,000kW lithium-ion battery pack.
Williams Advanced Engineering (WAE), which also works with Formula E vehicles, announced in January that they would be tapped to provide advanced battery technologies for the Evija. Considering how competitive Formula E racing is, it comes as no surprise that WAE is less than forthcoming about sharing BMS-related specs. Primarily, WAE relies on demonstrating the power of their battery management systems—what they call the "Brains Behind the Battery"—at events such as Hybrid Vehicle Technology Expo in May where they showcased their work on Aston Martin's first electric vehicle, the Rapide E.
While this car is out of reach for most, it does demonstrate how electric-powered vehicles can rival their gas counterparts.
Addressing BMS Thermal Management: i-CoBAT
Just last week, a trio of companies—Ricardo, M&I Materials, and WMG—announced a bid to improve EV design by developing advanced cooling technology that relies on submerging battery cells in a dielectric fluid.
M&I Materials Product Group Director James O'Brien was quoted as crediting Ricardo with bringing "extensive knowledge of EV battery pack and battery management system design and thermal management to the project.
Rendering of an example EV battery system. Image from Ricardo
According to Ricardo, current EV technologies rely on air cooling or "cold plate cooling" with a refrigerant to stabilize the temperature of an EV battery system. While this is not the first example of immersion cooling for EVs, this one apparently aims to use a biodegradable coolant called MIVOLT that boasts a pour point of -75°C (which they present as being extremely low) and a fire point of 218°C.
The project hopes to increase the longevity of EV batteries while also decreasing charge times and costs.
The i-CoBAT project was spurred by the UK's "Faraday Battery Challenge", a nearly $300 million government-funded push for companies to collaborate and innovate new technologies that will aid the country in their pursuit of banning new conventional gas- and diesel-powered vehicles by 2040.
Battery Management Market Set to Grow
A recent study from Future Market Insights suggests that EV battery management systems will grow significantly by 2025.
When electric cars were first introduced, one of their biggest disadvantages was in their charging, particularly the long wait times for full charges and the lack of available charging stations. Arguably, these issues would not have posed such obstacles if electric cars had significant ranges—but typical electric cars are lucky to get 150 miles on a full charge. (Tesla cars are currently stated as being able to travel as far as 250 miles, but this depends on environmental factors.)
The second issue of charging stations is being addressed in some areas, especially in Europe where governments are pushing for net-zero carbon emissions (such as in the UK) and electric cars are becoming more popular.
Since battery management systems are fundamental in EVs, it comes as no surprise that the demand for more intelligent systems will also increase. The Bosch BMS is a good example of how a company is planning to integrate machine learning to potentially increase the effective range of EVs and a car that has the biggest range will be arguably the most popular.
It's important to remember, of course, that battery management systems are not just applicable to cars; they may also play a role in renewable energy power stations, which need to store power during times of high energy output when the grid cannot accept any more power.
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