Setting Your Battery Strategy: An Act of Balance

Magnus Bredin is an experienced engineering manager currently leading the Battery and EPS System Engineering team at Polestar. With over two years in this role, he brings a strong background in mechatronics, robotics and automation. Magnus has a proven track record in the logistics and supply chain industry, where he developed expertise in Failure Mode and Effects Analysis (FMEA), embedded systems and business process improvement.

Through this article, Bredin emphasizes the importance of battery strategy and concept in the development of electric vehicles. He highlights that the battery is a complex and critical component that can significantly impact the success of an electric vehicle project.

Regardless of if you are building on a hobby project in the garage or if you are into high-volume automotive development, your battery strategy and concept are a game changer.

In electrical vehicles, the battery is the most complex and cost-driving component and system. To set the correct strategy and concept early is a make or break to your success.

I sometimes describe engineering as the profession of compromises, and it is an act of balance to make correct choices to end up with the best overall solution.

There are a lot of different systems, concepts and choices to be carefully selected depending on the requirements and applications. The included concepts, technologies and systems can almost be endless, so the first step is to define and prioritize which areas to include and, as important, which areas to not include.

“There are a lot of different systems, concepts and choices to be carefully selected depending on the requirements and applications. The included concepts, technologies and systems can almost be endless, so the first step is to define and prioritize which areas to include and, as important, which areas to not include.”

Below are some examples of areas that we selected to look deeper into in one of my latest projects:

Integration Cell to Pack, Battery swapping, voltage level, cooling/heating concept. Modularization. charging versus sizing of energy, cell type and format.

To get a bit more down to earth, I will go a bit more into details on one of these areas:

Concept: Should the battery be easy to change for the end user or highly integrated into the vehicle?

This is an area that is naturally quite dependent on the application. In one end, you can see automotive applications with high capacity where trends are more integration to the vehicle down to cell-to-pack solutions. On the other end, you have e-bikes or hand tools with small capacity and very simple swapping solutions.

However, you can also see initiatives to the opposite from both these corner cases. Swapping solutions on high-end automotive as well as E-bike solutions when you integrate the battery in the frame. So, the answer is not that simple that you just can look at the size.

For our project, the main parameters that came into play were:

    ●  Capacity need and connected to this physical size and weight

    ●  Drive cycle/usage/environment

    ●  Charging possibilities and performance

    ●  Cost

In this example, we ended up in the conclusion that we prioritized low weight and the possibility to easily swap batteries. This was also an application that was to be used in winter conditions and low temperatures so being able to store and charge the battery in a controlled environment was ranked highly.

We ended up with a concept and strategy to prioritize less size and capacity to enable the possibility of being able to easily switch batteries. Instead of trying to push in as much energy as possible and more deep integration to the vehicle. Possibility and flexibility for the user to bring along one extra battery if needed.

In my opinion, setting up this kind of high-level concept/strategies early in a project is very important. It can be used generically on all concepts, from software to hardware.

It is also a good framework to fall back on when you come into decision-making on a more detailed level during the development.

During development, it is also important to frequently stop up and reflect on whether the design is still in line with the high-level strategy that was set up.

As important is to frequently also stop up and reflect and review if the strategy that was set in the start still holds. In the dynamic and constantly changing technology and market of batteries and EV technology, cost and state of the art can change over a short time. Is the strategy still in balance?