NOVELTY - The pack (100) has rechargeable cell arranged in the battery pack. A set of exposed host contacts arranged on the battery pack that provide power from the rechargeable cell to a host device (202) coupled to the battery pack. A charge protection circuit element is coupled between rechargeable cell and power contact and that allows charging. A discharge circuit having circuit element coupled in parallel with the charge protection circuit element that allows a discharge current through the power contact.    USE - Portable rechargeable battery pack used to power portable devices.    ADVANTAGE - The portable rechargeable battery pack contains a charge protection circuit that prevents or limits current from flowing in the opposite direction of a charging current through the charging contacts. The portable rechargeable battery packs that have both charging contacts and host contacts where the charging contacts have a charge protection portion to prevent discharge current drawn from the charging contacts but through which a charge current flow, and providing power from the portable rechargeable battery pack though the charging contacts via an external adapter. The positive temperature coefficient (PTC) polymer switch acts as a current limiter and allows enough current to flow from the rechargeable battery cell(s) to the power contact to power a device through the external adapter, and limits the current in a resettable fuse manner to prevent an unnecessarily high current level to flow out of the charging contacts without interfering with powering the host device. A charge protection circuit element is coupled between rechargeable cell and power contact and that allows charging and prevents discharging of the rechargeable cell through the set of charging contacts.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (1) a portable rechargeable battery pack system;    (2) an external adapter for use with a portable rechargeable battery pack; and    (3) a portable power system.    DESCRIPTION OF DRAWING(S) - The drawing shows an isometric view of a portable rechargeable battery pack system.    Portable rechargeable battery pack (100)    Charging contacts (104)    Portable rechargeable battery pack system (200)    Host device (202)    External adapter (206)