A system for protecting a vehicle battery intended to store energy from a network via a charge path or to supply energy to the network via a discharge path, the system comprising at least one current converter, at least one first isolation switch of the converter arranged between the charge path and/or the discharge path and the converter upstream of the converter and at least one external module for protecting the battery independent of the converter, arranged downstream of the converter, the battery being electrically connected to the converter, the converter being electrically connected to the mains via the charge path and the discharge path, the first isolation switch being suitable for connecting or disconnecting the converter to the mains upstream of the converter with respect to the battery, each external module for protecting the battery comprising: - an external system for measuring the voltage at the terminals of the battery, and - a control module configured to receive the value of the voltage measured by the external measurement system and being configured to isolate the battery from the mains when an undervoltage lower than a predetermined minimum reference voltage is measured by the external measurement system or when an overvoltage higher than a predetermined maximum reference voltage is measured by the external measurement system, the control module isolating the battery by opening the first isolation switch of the converter when an overvoltage or undervoltage is measured by the external voltage measurement system, characterised in that the converter comprises a first system for measuring the voltage at the terminals of the battery and a first control device capable of opening the first isolation switch of the converter when an overvoltage or undervoltage is measured by the first measuring system. the system comprising at least one current converter, at least one first isolation switch of the converter arranged between the charge path and/or the discharge path and the converter upstream of the converter and at least one external module for protecting the battery independent of the converter, arranged downstream of the converter, the battery being electrically connected to the converter, the converter being electrically connected to the mains via the charge path and the discharge path, the first isolation switch being suitable for connecting or disconnecting the converter to the mains upstream of the converter with respect to the battery, each external module for protecting the battery comprising: - an external system for measuring the voltage at the terminals of the battery, and - a control module configured to receive the value of the voltage measured by the external measurement system and being configured to isolate the battery from the mains when an undervoltage lower than a predetermined minimum reference voltage is measured by the external measurement system or when an overvoltage higher than a predetermined maximum reference voltage is measured by the external measurement system, - an external system for measuring the voltage at the terminals of the battery, and - a control module configured to receive the value of the voltage measured by the external measurement system and being configured to isolate the battery from the mains when an undervoltage lower than a predetermined minimum reference voltage is measured by the external measurement system or when an overvoltage higher than a predetermined maximum reference voltage is measured by the external measurement system, the control module isolating the battery by opening the first isolation switch of the converter when an overvoltage or undervoltage is measured by the external voltage measurement system, characterised in that the converter comprises a first system for measuring the voltage at the terminals of the battery and a first control device capable of opening the first isolation switch of the converter when an overvoltage or undervoltage is measured by the first measuring system.