Scott M. Garrett

Apparatus and method of simulating high battery temperature in a rechargeable battery

A device (111) for simulating a high battery temperature used in charging a rechargeable cell (101). The device takes advantage of a control signal generated by a voltage control circuit (103) used to disconnect a rechargeable cell (101) from a charging system (105) when a predetermined voltage is reached. The device (111) is generally used with cells having a lithium based chemistry and requiring a different charging regime then nickel chemistry cells. The device (111) is activated by the control signal from control circuit (103) which detects a predetermined voltage from rechargeable cell (101) enabling thermistor (113) to change its state. This change is detected by the charging system (105) which alters its mode of operation from a rapid charging rate to a slower charging rate. The device is retrofitable to existing rechargeable batteries allowing them to be charged using existing charging systems alien to the rechargeable battery.

Battery lockout circuit and battery pack using same

A lockout circuit is provided in a battery pack (10) which blocks charging by incompatible chargers while allowing charging by a compatible charger (12). The battery comprises a battery cell or cells (22), and a switch circuit (24). The switch circuit blocks charge current until a switch disable signal is provided to a switch disable contact (18). The switch circuit provides a one way bypass so that the battery may provide power to a device. To eliminate voltage drop while powering a device, a current sense circuit is provided to detect discharge current, and disable the switch circuit.

Apparatus for controlling excess recharge current applied to a battery

A battery recharge current source 12 provides a recharge current 14 to battery cells 16. Recharge current 14 is in excess of an optimum recharge current level for battery cells 16 and is divided into currents 26 and 28 by variable shunt load 24 as controlled by charge current control circuit 18. Charge current control circuit 18 is comprised of current sense circuit 20 and load control circuit 22. Current sense circuit 20 produces a current sense signal in response to current through battery cells 16. Load control circuit 22 is responsive to the current sense signal and controls variable shunt load 24 as needed to conduct excess current away from the battery cells.