Patent ID: 9472979
Filing Date: 2016-10-18
CPC Classification: H02J

Claim Text:
1. A method of operating a power tool with a first battery and a second battery connected in parallel, a first switch being connected in series with the first battery and the power tool, a second switch being connected in series with the second battery and the power tool, the method comprising: with a controller, monitoring a first voltage of the first battery and a second voltage of the second battery; when the first voltage of the first battery and the second voltage of the second battery are within a predetermined range, closing the first switch to connect the first battery to the power tool and closing the second switch to connect the second battery to the power tool; when the first voltage of the first battery is outside of the predetermined range of the second voltage of the second battery and the second voltage of the second battery is greater than the first voltage of the first battery, opening the first switch to disconnect the first battery from the power tool; and when the second voltage of the second battery is outside of the predetermined range of the first voltage of the first battery and the first voltage of the first battery is greater than the second voltage of the second battery, opening the second switch to disconnect the second battery from the power tool.