Battery assembly controller which monitors voltages of secondary batteries

1. A battery assembly controller controlling terminal voltages of a plurality of series-connected secondary batteries to be equal, the controller comprising:

a discharge circuit selectively reducing the terminal voltages of the secondary batteries; and

a monitoring circuit directly connected to positive and negative electrodes of the secondary batteries to monitor the terminal voltages of the secondary batteries, wherein

the discharge circuit includes:

a plurality of switches, each being connected to positive and negative electrodes of associated one of the secondary batteries, and

a control circuit controlling not to turn on odd-numbered and even-numbered switches simultaneously, where the switches are sequentially numbered as 1, 2, 3, . . . , from a high-potential side,

each of the switches is a MOS transistor, and

the discharge circuit further includes:

a plurality of resistors, each being connected between a gate and a source of one of the MOS transistors,

a plurality of current supplies, and

a plurality of other switches, each being connected between the gate of one of the MOS transistors and associated one of the current supplies.

2. The battery assembly controller of claim 1 , wherein the monitoring circuit includes a filtering capacitor switchably connected to the secondary batteries.

3. The battery assembly controller of claim 1 , wherein the monitoring circuit includes a filtering capacitor and a resistor switchably connected to the secondary batteries.

4. The battery assembly controller of claim 1 , wherein each of the switches includes a plurality of sub-switches connected in series.

5. The battery assembly controller of claim 1 , wherein each of the switches includes a sub-switch and a resistor, which are connected in series.

6. The battery assembly controller of claim 1 , wherein the control circuit controls not to turn on adjacent ones of the switches simultaneously.

7. The battery assembly controller of claim 1 , wherein

one of the switches with highest potential is a p-channel MOS transistor, and

one of the switches with lowest potential is an n-channel MOS transistor.

8. The battery assembly controller of claim 1 , wherein the discharge circuit further includes a plurality of short-circuit switches, each being connected between a gate and a source of one of the MOS transistors.

9. The battery assembly controller of claim 1 , wherein the discharge circuit further includes a plurality of resistors, each being connected in parallel to associated one of the switches.

10. The battery assembly controller of claim 9 , wherein the discharge circuit further includes a plurality of Zener diodes, each being connected in series to associated one of the resistors.