Battery device
View Patent ↗Provided is a battery device having high overcurrent detection current accuracy that suppresses increases in a resistance value of a charge/discharge path and in a manufacturing cost. A first charge/discharge control device is configured to monitor a charge/discharge current with a voltage generated across both ends of a charge/discharge control switch, and a second charge/discharge control device is configured to monitor the charge/discharge current with a voltage generated across both ends of a current sensing resistor. A field effect transistor forming the charge/discharge control switch is selected based on a desired ON resistance value. The charge/discharge control switch of the first charge/discharge control device includes a field effect transistor having the desired ON resistance value, and a charge/discharge control switch of the second charge/discharge control device includes a field effect transistor having an ON resistance value other than the desired ON resistance value.
1. A battery device, comprising:
a secondary battery having positive and negative electrodes;
positive and negative terminals connected, respectively, to the positive and negative electrodes of the secondary battery;
a switching line connecting between the positive electrode of the secondary battery and the positive terminal or between the negative electrode of the secondary battery and the negative terminal;
a first charge/discharge control device and a second charge/discharge control device both connected to the secondary battery in parallel to the second battery between the positive and negative electrodes of the secondary battery, wherein the first charge/discharge control device comprises a first overcurrent detection terminal for monitoring a charge/discharge current flowing through the secondary battery, and the second charge/discharge control device comprises a second overcurrent detection terminal for monitoring the charge/discharge current;
first and second charge/discharge control switches connected in series in the switching line, wherein the first charge/discharge control switch is turned off by the first charge/discharge control device to cut the switching line, and the second charge/discharge switch is turned off by the second charge/disgorge control device to cut the switching line; and
a current sensing resistor connected in the switching line upstream of the first charge/discharge control switch, wherein
the first overcurrent detection terminal of the first charge/discharge control device is connected to the switching line between a downstream end of the current sensing resistor and the first charge/discharge control switch so that the first charge/discharge control device monitors a voltage across the current sensing register to thereby monitor the charge/discharge current flowing through the secondary battery, and
the second overcurrent detection terminal of the second charge/discharge control device is connected to the switching line downstream of the second charge/discharge control switch so that the second charge/discharge control device monitors a voltage across the second charge/discharge control switch to thereby monitor the charge/discharge current flowing through the secondary battery.
2. A battery device according to claim 1 ,
wherein the second charge/discharge control switch includes a second field effect transistor selected to have a second ON resistance value that falls within a small variance from a desired ON resistance, and
wherein the first charge/discharge control switch includes a first field effect transistor selected to have a second ON resistance value close to the desired ON resistance value, the first field effect transistor being selected without regard to whether or not the second ON resistance value falls within the small variance from the desired ON resistance.
3. A method for manufacturing a battery device,
the battery device comprising:
a secondary battery having positive and negative electrodes;
positive and negative terminals connected, respectively, to the positive and negative electrodes of the secondary battery;
a switching line connecting between the positive electrode of the secondary battery and the positive terminal or between the negative electrode of the secondary battery and the negative terminal;
a first charge/discharge control device and a second charge/discharge control device both connected to the secondary battery in parallel to the second battery between the positive and negative electrodes of the secondary battery, wherein the first charge/discharge control device comprises a first overcurrent detection terminal for monitoring a charge/discharge current flowing through the secondary battery, and the second charge/discharge control device comprises a second overcurrent detection terminal for monitoring the charge/discharge current;
first and second charge/discharge control switches connected in series in the switching line, wherein the first charge/discharge control switch is turned off by the first charge/discharge control device to cut the switching line, and the second charge/discharge switch is turned off by the second charge/disgorge control device to cut the switching line; and
a current sensing resistor connected in the switching line upstream of the first charge/discharge control switch, wherein
the first overcurrent detection terminal of the first charge/discharge control device is connected to the switching line between a downstream end of the current sensing resistor and the first charge/discharge control switch so that the first charge/discharge control device monitors a voltage across the current sensing register to thereby monitor the charge/discharge current flowing through the secondary battery, and
the second overcurrent detection terminal of the second charge/discharge control device is connected to the switching line downstream of the second charge/discharge control switch so that the second charge/discharge control device monitors a voltage across the second charge/discharge control switch to thereby monitor the charge/discharge current flowing through the secondary battery,
the method comprising:
constructing the second charge/discharge control switch with a second field effect transistor selected to have a second ON resistance value that falls within a small variance from a desired ON resistance; and
constructing the first charge/discharge control switch with a first field effect transistor selected to have a second ON resistance value close to the desired ON resistance value, the first field effect transistor being selected without regard to whether or not the second ON resistance value falls within the small variance from the desired ON resistance.