ELECTRIC TOOL POWERED BY A PLURALITY OF BATTERY PACKS AND ADAPTER THEREFOR

An electrical apparatus includes first and second battery interfaces disposed on a housing for electrically and mechanically connecting first and second battery packs in series. A controller is disposed within the housing and includes an apparatus microprocessor that receives first and second communication signals respectively outputted from respective microprocessors of the first and second battery packs. A first signal communication path communicates the first communication signal from the first battery pack microprocessor to the apparatus microprocessor by shifting a first voltage range of the first communication signal to a second voltage range that is suitable for inputting into the apparatus microprocessor. A second signal communication path communicates a third communication signal from the apparatus microprocessor to the first battery pack microprocessor by shifting the second voltage range of the third communication signal to a first voltage range that is suitable for inputting into the first battery pack microprocessor.