ELECTROCHEMICAL CELL BALANCING CIRCUITS AND METHODS
A system for charging and/or discharging electrochemical cells of a pack that provides power to a load of an apparatus, such as a vehicle. The system can include a circuit coupled to an electrochemical cell of the pack and configured to charge and/or discharge the electrochemical cell at a plurality of times occurring throughout a period in which the apparatus is dormant. The system can have a lower power draw. The system can have automatic timeouts to stop charging and/or discharging the cells when an auxiliary battery is disconnected.
1 . A system for charging and/or discharging electrochemical cells of a pack that provides power to a load of an apparatus, the system comprising:
a circuit coupled to an electrochemical cell of the pack and configured to charge and/or discharge the electrochemical cell at a plurality of times occurring throughout a period in which the apparatus is dormant.
2 . The system of claim 1 , wherein no power is drawn by the load from the pack when the apparatus is dormant.
3 . The system of claim 2 , wherein no current is flowing into or out of the pack when the apparatus is dormant.
4 . The system of claim 1 , wherein the apparatus is a vehicle and the load comprises a motor of the vehicle.
5 . The system of claim 4 , wherein the vehicle is dormant when the vehicle is turned off and the pack is not charging.
6 . The system of claim 4 , wherein the vehicle is dormant when the vehicle is turned off and no current is flowing into or out of the pack.
7 . The system of claim 1 , further comprising:
a controller configured to generate a control signal,
wherein the circuit is configured to charge and/or discharge the electrochemical cell in response to the control signal.
8 . The system of claim 7 , wherein the controller is configured to balance voltages or states of charge of the electrochemical cells of the pack.
9 . The system of claim 7 , wherein the circuit is configured to charge and/or discharge the electrochemical cell in response to the control signal and to automatically stop charging and/or discharging the electrochemical cell after a predetermined time period.
10 . The system of claim 7 , wherein the circuit is configured to charge and/or discharge the electrochemical cell for a predetermined time period in response to a refresh signal.
11 . The system of claim 10 , wherein the controller is configured to operate in at least a first power mode and a second power mode, wherein the controller uses less power in the second power mode than in the first power mode, wherein the controller is configured to generate the control signal when the controller is in the first power mode and not when the controller is in the second power mode, and wherein the system is configured to provide the refresh signal to the circuit when the controller is in the second power mode.
12 . The system of claim 10 , wherein the circuit is a first circuit coupled to a first electrochemical cell of the pack, and the system further comprises:
a second circuit coupled to a second electrochemical cell of the pack and configured to charge and/or discharge the second electrochemical cell,
wherein the first circuit is configured to receive the refresh signal from the second circuit.
13 . The system of claim 7 , wherein the control signal is a first control signal and the controller is further configured to generate a second control signal, and wherein the circuit is configured to stop charging and/or discharging the electrochemical cell in response to the second control signal.
14 . The system of claim 1 , wherein the circuit is a latching circuit configured to store a balancing command.
15 . The system of claim 14 , wherein the system is powered using a battery separate from the pack, and the circuit is configured such that if the battery is disconnected, the circuit will stop charging and/or discharging the battery within a predetermined amount of time.
16 . The system of claim 1 , wherein the charging and/or discharging is controlled at least in part by an application specific integrated circuit (ASIC), and the system is configured to repeatedly send a refresh signal to the ASIC so that the ASIC keeps charging and/or discharging one or more selected cells of the pack.
17 . A system for charging and/or discharging electrochemical cells of a pack, the system comprising:
a controller configured to generate a control signal; and
a circuit coupled to an electrochemical cell of the pack, the circuit being configured to charge and/or discharge the electrochemical cell in response to the control signal and to automatically stop charging and/or discharging the electrochemical cell after a predetermined time period.
18 . The system of claim 17 , wherein the circuit comprises:
a resistive element;
a capacitor; and
a transistor having a control terminal coupled to the resistive element and the capacitor.
19 . The system of claim 18 , further comprising:
an amplifier coupled to the control terminal to amplify a signal provided by the resistive element and the capacitor.
20 . The system of claim 17 , wherein the circuit is a first circuit coupled to a first electrochemical cell of the pack, and the system further comprises:
a second circuit coupled to a second electrochemical cell of the pack and configured to charge and/or discharge the second electrochemical cell in response to the control signal.
21 . The system of claim 20 , wherein the second circuit is connected to the first circuit to receive the control signal from the first circuit.
22 . The system of claim 17 , wherein the control signal is a first control signal and the controller is further configured to generate a second control signal, and wherein the circuit is configured to stop charging and/or discharging the electrochemical cell in response to the second control signal.
23 . A system for charging and/or discharging electrochemical cells of a pack, the system comprising:
a controller configured to generate at least one control signal; and
a plurality of circuits individually coupled to respective electrochemical cells of the pack to charge and/or discharge the electrochemical cells in response to the at least one control signal,
wherein the system is configured to draw no more than 100 mA on average from an auxiliary battery when in operation.
24 . The system of claim 23 , wherein the system is configured to draw no more than 50 mA on average from the auxiliary battery when in operation.
25 . The system of claim 24 , wherein the system is configured to draw no more than 2 mA on average from the auxiliary battery when in operation.
26 . The system of claim 23 , wherein the pack is configured to provide power to a motor of a vehicle.
27 . The system of claim 26 , wherein the controller is configured to generate the at least one control signal to control the plurality of circuits to charge and/or discharge the electrochemical cells of the pack at a plurality of times occurring throughout a period in which the vehicle is dormant.
28 . The system of claim 23 , wherein the system is configured to be powered by the auxiliary battery.
29 . The system of claim 23 , wherein the system is configured to be powered by the pack.
30 . The system of claim 23 , wherein the system is powered using no more than 100 mA on average.
31 . The system of claim 30 , wherein the system is powered using no more than 50 mA on average.
32 . The system of claim 31 , wherein the system is powered using no more than 2 mA on average.