BATTERY PROTECTION SYSTEMS

A system includes multiple protection modules. Each protection module includes monitoring terminals that monitor battery cells' status, an output terminal that outputs a protection signal if an abnormal condition in the cells is detected, a switching terminal that receives a switching signal, and detection circuitry that switches from a normal-working mode to a fast-test mode if receiving the switching signal, delays outputting the protection signal for a first time interval if the abnormal condition is detected in the normal-working mode, and delays outputting the protection signal for a second time interval, less than the first time interval, if the abnormal condition is detected in the fast-test mode. In the protection modules, the switching terminal of a first protection module and a monitoring terminal of the first protection module are coupled to a second protection module and receive a protection signal from the output terminal of the second protection module.