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The traction battery, what’s that?
An electric vehicle has two batteries: a 12V battery for certain accessories, equivalent to the battery in combustion engine vehicles, and a traction battery (or battery pack), which powers the car’s electric motor. The traction battery is made up of dozens of small batteries, called cells, connected to each other.
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Why and how does the traction battery of my electric vehicle degrade ?
As an electric vehicle ages, it loses range. This loss of range is due to the chemical degradation of the cells that make up the battery pack. This phenomenon, called aging, strongly depends on the usage and storage conditions of the vehicle. For example, high temperatures or fast charging accelerate the aging of traction batteries.
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How to measure the loss of range of my battery ?
The state of the battery is measured using the State of Health.
The State of Health* (SOH) reflects the health status of the battery as a percentage. This number provides an indication of the degradation of the battery pack. It represents the ratio between the maximum electrical energy that a traction battery can provide at a given time (t) and the maximum electrical energy it could provide when brand new. For example, the SOH of a new electric car is 100%.
The Battery Management System (BMS) regularly monitors the state of the battery and calculates the SOH. This way, the BMS can, for example, adjust the displayed range on the dashboard based on the actual state of the battery pack.
For the driver, it is essential to regularly measure their SOH to ensure normal degradation or adjust their usage in case of premature aging.
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