Electric tool powered by a plurality of battery packs and adapter therefor

An electric power tool comprising:

• a power tool housing having a first battery pack interface for a first battery pack and a second battery pack interface for a second battery pack, wherein a positive battery electrode of the first battery pack interface is connected in series with a negative battery electrode of the second battery pack interface, and
• at least one bypass circuit disposed within the power tool housing and comprising a first diode that electrically connects the positive battery electrode and a negative battery electrode of the first battery pack interface and a second diode that electrically connects a positive battery electrode and the negative battery electrode of the second battery pack interface,
• wherein the first and second diodes are also connected in series between the negative battery electrode of the first battery pack interface and the positive battery electrode of the second battery pack interface and
• the first diode has a reverse breakdown voltage that is higher than a power supply voltage of the first battery pack and the second diode has a reverse breakdown voltage that is higher than a power supply voltage of the second battery pack.

An adapter configured for detachably connecting a plurality of battery packs to a tool housing of a hand-held electric power tool, wherein each battery pack comprises a microprocessor and memory and the adapter is detachable from the tool housing of the electric power tool, the adapter comprising:

• an adapter housing configured to detachably latch the first and second battery packs;
• a circuit disposed within the adapter housing that electrically connects power terminals of the first and second battery packs in series;
• a controller disposed within the adapter housing and comprising an adapter microprocessor configured to receive signals respectively outputted from the microprocessors of the first and second battery packs, wherein the microprocessor of the first battery pack outputs a first signal at a first voltage level and the microprocessor of the second battery pack outputs a second signal at a second voltage level different from the first voltage level;
• and
• a first level-shifter disposed within the adapter housing and electrically connected between the controller and the microprocessor of the first battery pack, the first level-shifter being configured to shift the first voltage level of the first signal to the second voltage level that is usable by the adapter microprocessor,
• a second level-shifter disposed within the adapter housing and electrically connected between the controller and the microprocessor of the first battery pack, the second level-shifter being configured to shift the second voltage level of a signal outputted from the controller to the first voltage level that is usable by the microprocessor of the first battery pack, and
• a circuit disposed within the adapter housing that electrically communicates the second signal at the second voltage level from the microprocessor of the second battery pack to the adapter microprocessor.

An adapter configured for connecting first and second battery packs to a main body of an electric power tool, the adapter being detachable from the main body of the electric power tool, the adapter comprising:

• an adapter housing having a first battery pack interface for the first battery pack and a second battery pack interface for the second battery pack, wherein a positive battery electrode of the first battery pack interface is connected in series with a negative battery electrode of the second battery pack interface, and
• at least one bypass circuit disposed within the adapter housing and comprising a first diode that electrically connects the positive battery electrode of the first battery pack interface and a negative battery electrode of the first battery pack interface and a second diode that electrically connects a positive battery electrode of the second battery pack interface and the negative battery electrode of the second battery pack interface,
• wherein the first and second diodes are also connected in series between the negative battery electrode of the first battery pack interface and the positive battery electrode of the second battery pack interface and
• the first diode has a reverse breakdown voltage that is higher than a power supply voltage of the first battery pack and the second diode has a reverse breakdown voltage that is higher than a power supply voltage of the second battery pack.

A power supply interface for a hand-held electric power tool having a microprocessor comprising:

• a first battery pack interface configured to detachably latch a first battery pack and comprising a first positive battery electrode input terminal, a first negative battery electrode input terminal and a first battery controller interface terminal,
• a second battery pack interface configured to detachably latch a second battery pack and comprising a second positive battery electrode input terminal, a second negative battery electrode input terminal and a second battery controller interface terminal, the first negative battery electrode input terminal being electrically connected in series with the second positive battery electrode input terminal within the power supply interface, wherein the first positive battery electrode input terminal is electrically connectable with the second negative battery electrode input terminal via a load of the electric power tool, and
• a first DC-to-DC converter disposed within the power supply interface and electrically connected with the first battery controller interface terminal, the first DC-to-DC converter being configured to proportionally step down a voltage of a first signal received at the first battery controller interface terminal, and
• a second DC-to-DC converter disposed within the power supply interface and electrically connected with the first battery controller interface terminal, the second DC-to-DC converter being configured to proportionally step up a voltage of a second signal received at the second DC-to-DC-converter to be supplied to the first battery controller interface terminal,
• wherein the first and second signals are microprocessor signals.

A power supply interface for an electric power tool comprising:

• a first battery pack interface configured to detachably attach a first battery pack and comprising a first positive battery electrode input terminal and a first negative battery electrode input terminal,
• a second battery pack interface configured to detachably attach a second battery pack and comprising a second positive battery electrode input terminal and a second negative battery electrode input terminal, the first negative battery electrode input terminal being electrically connected in series with the second positive battery electrode input terminal, wherein the first positive battery electrode input terminal is electrically connectable with the second negative battery electrode input terminal via a load of the electric power tool,
• a first diode having a cathode electrically connected to the first positive battery electrode input terminal and an anode electrically connected to the first negative battery electrode input terminal, the first diode having the property that it becomes conductive when a reverse voltage is generated across the first positive battery electrode input terminal and the first negative battery electrode input terminal, and
• a second diode having a cathode electrically connected to the second positive battery electrode input terminal and an anode electrically connected to the second negative battery electrode input terminal, the second diode having the property that it becomes conductive when a reverse voltage is generated across the second positive battery electrode input terminal and the second negative battery electrode input terminal.