An EV that will not become ready can display battery-related warnings without identifying the final cause. Preserve the exact message and a full diagnostic report before assuming that the complete battery needs replacement.
Battery control involves several functions
Bosch’s battery-management documentation describes battery control, cell-supervision circuits and a disconnect unit. It lists measurement and control functions, including battery current, cell-voltage information and contactor control. These are examples of system architecture, not a repair instruction for every vehicle.
A report should identify which controller stored each fault and the conditions in which it was recorded. Different vehicle designs and software versions need their own diagnostic information.
Useful information for an enquiry
Describe whether the warning began during charging, parking or an attempted drive. Include the indicated state of charge and any recent low-voltage battery work, software update, collision or water exposure. Save the original code descriptions and status rather than replacing them with a generic internet explanation.
Ask your qualified technician to summarise its findings and identify the exact assembly under investigation. Distinguish an observed value from a proposed cause.
Keep high-voltage work with qualified personnel
Do not open the battery, bridge a contactor or attempt to defeat an interlock. HSE guidance calls for appropriate competence, equipment and manufacturer-specific precautions for electric and hybrid work.
Start an EV or hybrid enquiry with the reports. Agree the vehicle-assessment and transport arrangements first; do not send a traction battery as an ordinary postal module.
References: Bosch — Battery management and disconnect systems; HSE — Electric and hybrid vehicles.