A rechargeable system includes: a charger (4); a battery pack (1); an adapter (3) configured to be electrically connected between the charger (4) and the battery pack (1), a cable (58) configured to be electrically connected between the battery pack (1) and the adapter. A battery-side microcomputer (526) controls the shutdown circuit (523) such that the shutdown circuit (523) disconnects the at least one of the positive terminal (5a) of the battery pack and the negative terminal (5b) of the battery pack (1) from the rechargeable battery (51) when detection of the battery-side microcomputer (526) indicates occurrence of at least one of two following events: one event is such that the rechargeable battery (51) is fully charged. Another event is such that the rechargeable battery (51) has some errors.