| US 7,589,500 B2 | ||
| Method and system for battery protection | ||
| Todd W. Johnson, Wauwatosa, Wis. (US); Jay J. Rosenbecker, Menomonee Falls, Wis. (US); Gary D. Meyer, Waukesha, Wis. (US); Jeffrey M. Zeiler, Delafield, Wis. (US); Kevin L. Glasgow, Lomira, Wis. (US); Jonathan Z. Zick, Waukesha, Wis. (US); Jeffrey M. Brozek, Whitefish Bay, Wis. (US); and Karl F. Scheucher, Waite Hill, Ohio (US) | ||
| Assigned to Milwaukee Electric Tool Corporation, Brookfield, Wis. (US) | ||
| Filed on May 24, 2005, as Appl. No. 11/138,070. | ||
| Claims priority of provisional application 60/574278, filed on May 24, 2004. | ||
| Claims priority of provisional application 60/574616, filed on May 25, 2004. | ||
| Claims priority of provisional application 60/582138, filed on Jun. 22, 2004. | ||
| Claims priority of provisional application 60/582728, filed on Jun. 24, 2004. | ||
| Claims priority of provisional application 60/582730, filed on Jun. 24, 2004. | ||
| Claims priority of provisional application 60/612352, filed on Sep. 22, 2004. | ||
| Claims priority of provisional application 60/626013, filed on Nov. 05, 2004. | ||
| Claims priority of provisional application 60/626230, filed on Nov. 09, 2004. | ||
| Claims priority of provisional application 60/643396, filed on Jan. 12, 2005. | ||
| Prior Publication US 2006/0091858 A1, May 04, 2006 | ||
| Int. Cl. H02J 7/00 (2006.01) | ||
| U.S. Cl. 320—134 [320/132; 320/114; 320/115] | 18 Claims |
| 1. A battery pack configured to supply power to a cordless power tool, the cordless power tool having a motor, the battery
pack comprising:
a plurality of battery cells operable to supply a battery pack discharge current to the motor of the cordless power tool,
each of the battery cells having a battery cell state of charge;
a switch operable to be alternately positioned in one of a conducting state and a non-conducting state, the switch further
operable to enable the supply of discharge current from the battery pack to the motor when the switch is positioned in the
conducting state and operable to interrupt the supply of discharge current from the battery pack to the motor when the switch
is positioned in the non-conducting state;
a controller electrically connected to the switch and to each of the battery cells via a respective connection to each cell,
operable to monitor the respective battery cell state of charge of each of the battery cells, operable to control operation
of the battery pack, and operable to control the positioning of the switch, the controller including a microcontroller; and
a plurality of electrical paths between the controller and the cell connections, each electrical path being associated with
a different one of the cell connections, wherein each electrical path among the plurality of electrical paths is independent
of the other electrical paths among the plurality of electrical paths, and wherein no two electrical paths share an electrically
conductive component,
wherein the controller modifies operation of the battery pack by causing the switch to move from the conducting state to the
non-conducting state to interrupt the supply of discharge current from the battery pack to the motor when the monitored respective
battery cell state of charge of one of the battery cells reaches a predetermined threshold.
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