The Rechargeable Battery Pack is an optional accessory for the personalDataRAM hand-held dust monitor/data logger. The pDR-BP is a modular unit for direct plug-in and rigid attachment to the person Data RAM. The pDR-BP contains a rechargeable nickel-metal-hydride (NiMH) battery pack designed to proved dc voltage power to the personlDataRAM allowing it to operate for an extended period of time without requiring line power or battery replacement. Plugging the rechargeable battery pack into the personalDataRAM automatically disconnects the internal battery of the instrument, preventing any interference between the internal and the external power sources. The pDR-BP can be recharged by means of the AC Power Supply provided as a standard accessory with the personalDataRAM. The pDR-BP used in combination with the pDR-AC, provides uninterruptible power operation, I.e. continuous operating over unlimited time, even during line power interruptions.