Different strategies in battery aging

How is your battery aging and what can you do to slow the process

Patrick Schabus

Before you start
Do you know what the "gross" and "net" energy values of an electric car battery mean? Do you know buffer full and empty? Read here the text on this topic.
If you are already familiar with usable and installed (obstructed, physical) energy, please read on. Our colleague Patrick Schabus writes about two possible ways of aging an electric car battery and gives advice on how to tune the treatment depending on the car, related to the way the battery is aging.
The degree of control, but also responsibility, determine strategies
There are two strategic approaches to manufacturing a battery for electric vehicles. The main difference is how far one is allowed to discharge the battery, i.e. how much the range of use of the energy is limited. However, this seemingly simple classification hides a complex issue of choosing the right electric car for you. If you already have one, you can adapt your strategy to your car to slow down the aging process.
Strategy 1 - Eating up the emergency reserve
In this method, the usable range between 100-0% charge level indication is more limited than technically necessary. That is, a certain amount of energy is "locked in" in the emergency reserve range. The driver therefore has less leeway, as the battery is predefined to protect itself. This results in less range when new than would be possible, but it remains constant for many years. If cell aging occurs, energy is released from the oversized emergency reserve to keep the energy constant between 100-0% charge level indication. The range only begins to decrease when the minimum emergency reserve is reached.
While this carefree package allows for less margin, it also provides additional safety because such a battery is automatically protected. Moreover, adequate handling of such a battery requires little in-depth knowledge.
Strategy 2 - Limitation of range
In the second method, the maximum technically possible range is available to the user between 100-0% charge level indication. However, any aging of the cells also reduces the range, since there is no energy to compensate. As a result, aging can become noticeable after just one year or improper handling.
If you own such a battery, it is important to know that the battery should be handled with special care.
Your battery will thank you if you behave responsibly, charge and discharge it properly (no deep discharge, preferably stay between 80-20), have good knowledge and use it regularly.
How to determine the battery type?
It is not possible to determine from the car model which strategy was implemented in the manufacture of your battery. But let's say roughly that the first strategy is followed by BMW, Kia, Hyundai, Audi, etc., while Tesla, Nissan, Renault, etc. prefer the second strategy. I repeat, however, this is not a reliable way to determine your battery type. You can get much more reliable information from the data sheet itself, which you received with the car. There you will find the gross and net values of your battery. If the difference between gross and net is greater (and more than 10%), the manufacturer uses the first strategy. And logically, if this value is lower (usually about 5%), it is about the second strategy. For example, Audi e-Tron is 95 kWh gross and 83.6 kWh net (strategy 1), but BMW i4 83.7 is kWh gross and 80.9 kWh net (strategy 2).
Tip: Always read through info from manufacturers! But it can also happen that the strategy of battery use suddenly changes during a new software update from the manufacturer.
Practice: When buying a car, it is always good to have this information so you can find the right battery type according to your needs. Personally, I would always choose strategy 2, because then you can use all the energy of the battery, which then allows for more freedom on longer trips (eg vacation trip). Those who use the electric car as a second car usually choose strategy 2.

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