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Limits to repairing a damaged EV battery
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In some situations, the entire EV battery may need to be replaced.
ST PHOTO: CHONG JUN LIANG
When an electric vehicle (EV) has been in an accident and the battery is damaged, can the damaged parts be replaced or must the whole battery pack be removed and substituted with a new one?
In theory, it is possible to replace damaged parts in an EV’s battery pack. However, there are a number of practical, technical and safety limitations.
The most common type of EV battery pack is built by assembling individual battery cells in the series. Each cell has a voltage of approximately 3.5 volts. When fully assembled, depending on the number of cells in the series, the battery packs are typically rated at 400 or 800 volts.
Inside the EV battery pack, the cells are assembled individually or in sub-units called modules.
The main casing, usually made from pressed aluminium, contains the battery cells or modules, an electrical network for the power and monitoring sensors plus the coolant channels. The entire pack is hermetically sealed, so it is air- and water-tight, and designed to withstand some level of impact.
In the event the battery management system detects an error in any battery cell or module, the housing can be unsealed by specialist technicians to replace the faulty individual component, and thereafter reassembled to its original sealed condition.
Repairing it this way avoids incurring thousands of dollars to replace the complete battery pack.
While the EV’s chassis is designed to prevent damage to the battery housing in a road accident, in severe collisions, there is a possibility of the unit sustaining impact damage.
When this happens, some cells or modules could be damaged, while the hermetic seal would be compromised, as would the electrical and cooling system connections on the housing.
Under such circumstances, replacing the damaged battery cells alone would not be sufficient and any distortion to the housing cannot be repaired to its original form to ensure a perfect seal.
Assuming the body and chassis can be repaired, the car can be made road-worthy only if the entire battery pack is replaced to guarantee the specified connection integrity, especially for the high-voltage cables, cooling system and hermetic seal. Shreejit Changaroth
