| 摘要 |
<p>When rechargeable batteries have been discharged to a selected voltage reference level, LED 29 (and/or buzzer BZ) and controller 32 may warn the operator that the rechargeable batteries should be recharged. Controller 32 may change the selected reference voltage level based upon use history information concerning the rechargeable batteries. The use history information may, e.g., be stored in EEPROM 52 of battery pack 40. Thus, the rechargeable batteries can be discharged to different voltage levels before the operator is warned that the rechargeable batteries should be recharged. In addition or in the alternative, switch 36 may be disposed between the rechargeable batteries and a motor (M). Controller 32 may open switch 36 when the detected voltage of the rechargeable batteries drops below the selected reference voltage level (or a derivative of the selected reference voltage level) in order to interrupt the flow of current to the motor (M). Thus, the rechargeable batteries can be prevented from being over-discharged and from developing memory effects, thereby prolonging the usable life of the rechargeable batteries. <IMAGE></p> |
