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Multi-battery pack for power tools

  • US 9,673,738 B2
  • Filed: 05/15/2015
  • Issued: 06/06/2017
  • Est. Priority Date: 05/16/2014
  • Status: Active Grant
First Claim
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1. A power tool comprising:

  • a motor;

    a first battery pack;

    a second battery pack;

    a first switching element coupled between the first battery pack and the motor;

    a second switching element coupled between the second battery pack and the motor; and

    a controller coupled to the first switching element and the second switching element, the controller havinga first pulse-width modulation (PWM) output coupled to the first switching element and outputting a first PWM signal to selectively close the first switching element, anda second PWM output coupled to the second switching element and outputting a second PWM signal to selectively close the second switching element,wherein a first duty cycle of the first PWM signal and a second duty cycle of the second PWM signal are determined by the controller based on a state of charge of the second battery pack relative to a state of charge of the first battery pack.

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