Battery monitor with alarm activated by voltage or temperature threshold

The invention provides a battery monitoring device and method for monitoring a battery. The battery monitoring device comprises a voltage sensor and an alarm. The voltage sensor is arranged to monitor the voltage of the battery and the alarm is arranged to be activated if the voltage sensor detects a voltage below a threshold level. The battery monitoring device may be configured to operate in a first mode or a second, the first mode of operation being when the battery is in a storage state, and the second mode of operation being when the battery is in a discharging state.