A method for charging a lithium ion secondary battery of the present invention includes a first step and a second step. In the first step, A, B, and C satisfy the relationship A>B and B<C, where A represents an average charging current value in the range where a charge rate of the lithium ion secondary battery is 0% or more and less than 40%, B represents an average charging current value in the range where the charge rate is 40% or more and 60% or less, and C represents an average charging current value in the range where the charge rate is more than 60%. In the first step, the ratio of C.sub.MAX to C.sub.MIN (C.sub.MAX/C.sub.MIN) is 1.01 to 3.00, where C.sub.MAX represents the maximum value of the charging current value and C.sub.MIN represents the minimum value of the charging current value.

A vacuum cleaner including a motor, a suction opening, an exhaust opening, and an air passageway in fluid communication with the suction source and the exhaust opening. The motor receives power from a power cord that enters the lower portion of the main body through a power cord opening. The main body also includes a drain opening, configured to allow egress of any liquid in the main body. The power cord opening is higher than the drain opening. The vacuum also includes a protective tubular frame that surrounds the battery. The tubular frame is energy-absorbing, and is removable and replaceable.

A vacuum cleaner including a motor, a suction opening, an exhaust opening, and an air passageway in fluid communication with the suction source and the exhaust opening. The motor receives power from a power cord that enters the lower portion of the main body through a power cord opening. The main body also includes a drain opening, configured to allow egress of any liquid in the main body. The power cord opening is higher than the drain opening. The vacuum also includes a protective tubular frame that surrounds the battery. The tubular frame is energy-absorbing, and is removable and replaceable.

Various embodiments provide a pack for holding and re-charging an e-cigarette. The pack includes a pack battery; a body portion including a tube for receiving an e-cigarette; a re-charging mechanism for re-charging the e-cigarette received into the tube using the pack battery, wherein the e-cigarette can be re-charged in the tube without disassembly of the e-cigarette; and a dual activation mechanism comprising two separate triggers for causing the re-charging mechanism to begin re-charging the e-cigarette received into the tube using the pack battery. The re-charging begins only in response to the direct activation by a user of both of the separate triggers.

A backup power supply device having a short charging time is provided. The backup power supply device for supplying power when a main power supply is under a power failure includes first and second battery packs connected in parallel, a charging circuit for charging the first and second battery packs, first and second discharging switches for causing the first and second battery packs to discharge to the load device respectively, and a control unit. The control unit compares the battery voltages of the first and second battery packs with an output voltage from the main power supply. The control unit sets the first and second discharging switches to ON when the battery voltages are lower than the output voltage. When the battery voltage of the battery pack exceeds the output voltage of the main power supply due to charging, the control unit sets the first discharging switch and the second discharging switch to OFF. Thereafter, after the first and second battery packs are fully charged, the control unit switches the first and second discharging switches to ON when the battery voltage has dropped to a dischargeable upper limit voltage.

A backup power supply device having a short charging time is provided. The backup power supply device for supplying power when a main power supply is under a power failure includes first and second battery packs connected in parallel, a charging circuit for charging the first and second battery packs, first and second discharging switches for causing the first and second battery packs to discharge to the load device respectively, and a control unit. The control unit compares the battery voltages of the first and second battery packs with an output voltage from the main power supply. The control unit sets the first and second discharging switches to ON when the battery voltages are lower than the output voltage. When the battery voltage of the battery pack exceeds the output voltage of the main power supply due to charging, the control unit sets the first discharging switch and the second discharging switch to OFF. Thereafter, after the first and second battery packs are fully charged, the control unit switches the first and second discharging switches to ON when the battery voltage has dropped to a dischargeable upper limit voltage.

Disclosed is a photovoltaic-electrochromic-battery all-in-one device in which the functions of a dye-sensitized solar cell, an electrochromic device, and a lithium secondary battery are fused into one device. The all-in-one device according to the disclosure includes a photoelectrode uses as an active layer of a dye-sensitized solar cell (DSSC), a counter electrode used as an electrochromic layer opposite to the photoelectrode, and an electrolyte containing a lithium salt. The all-in-one device according to the disclosure allows the function of the DSSC that generates electrons by receiving solar energy, the function of an electrochromic device (ECD) that blocks light by discoloring an electrode with generated electrons, and the function of a lithium secondary battery (LIB) that stores generated electrons and uses the stored electrons again to be all implemented by one device.

A wireless charging system includes a platform having a substantially horizontal upper surface configured to support a vehicle and an induction coil coupled to the platform. The induction coil is configured to receive electrical energy from an energy source and generate a magnetic field above the upper surface, the magnetic field being positioned to wirelessly transfer the electrical energy to the vehicle while the vehicle is positioned atop the platform.

A wireless charging system includes a platform having a substantially horizontal upper surface configured to support a vehicle and an induction coil coupled to the platform. The induction coil is configured to receive electrical energy from an energy source and generate a magnetic field above the upper surface, the magnetic field being positioned to wirelessly transfer the electrical energy to the vehicle while the vehicle is positioned atop the platform.

A lithium secondary battery pack of the present invention includes: a lithium secondary battery including an electrode body formed of a positive electrode and a negative electrode facing each other and a separator interposed therebetween, and a non-aqueous electrolyte; a PTC element; and a protection circuit including a field effect transistor. The lithium secondary battery has an energy density per volume of 450 Wh/L or more, the lithium secondary battery has a current density of 3.0 mA/cm.sup.2 or less, and a relational expression (1) and a relational expression (2) below are established where A (mΩ) is an impedance of the lithium secondary battery and B (mΩ) is an impedance of the entire circuit unit of the lithium secondary battery pack excepting the impedance A (mΩ) of the lithium secondary battery:
A≤50 mΩ  (1)
B/A≤1  (2).