High voltage battery pack cycler for a vehicle
An off-board battery cycler is used to condition an on-board battery system used in electric or hybrid electric vehicles. The battery cycler periodically discharges the vehicle's high voltage traction battery to eliminate battery “memory” that can prevent the battery from being fully charged. The cycler also recharges both the high voltage battery and an on-board low voltage battery used to power the vehicle's electrical system. High voltage AC power used in recharging the high voltage battery is switched using contactors physically isolated within the battery cycler, in order to protect operating personnel from coming onto contact with high voltage. Faults and malfunctions are recorded by the vehicle's on-board controller
1. Apparatus for controlling the charge on a battery system for a vehicle, the battery system including a first, low voltage battery for operating electrical systems on the vehicle and a second, high voltage traction battery, comprising:
a battery cycler adapted to charge both the low voltage battery and the high voltage battery, said battery cycler further adapted to discharge the high voltage battery, said battery cycler off-board said vehicle; and,
a controller adapted to control the operation of the battery cycler including discharge of said high voltage battery, said controller on-board said vehicle.
2. The apparatus of claim 1 , wherein:
the battery cycler is further operable for periodically discharging the high voltage battery, and the controller is operable for controlling the battery cycler to achieve a preselected state of charge on the high voltage battery.
3. The apparatus of claim 1 , wherein the battery cycler includes:
a constant current source for delivering constant charging current to the high voltage battery during charging of the high voltage battery, and a switching circuit operated by the controller for coupling the constant current source with the high voltage battery.
4. The apparatus of claim 1 , wherein the battery cycler includes:
a first releasable connection for connecting the battery cycler with the high voltage battery, and a second releasable connection for connecting the battery cycler with the controller.
5. The apparatus of claim 1 , wherein the battery cycler includes a manual switch operable by a user for initiating the operation of the battery cycler.
6. The apparatus of claim 1 , wherein the controller senses the state of charge of the high voltage battery and delivers a signal to the battery cycler causing the cycler to recharge the high voltage battery when the state of charge falls below a preselected level.
7. The apparatus of claim 1 , wherein:
the controller periodically delivers a first, discharge control signal to the battery cycler causing the battery cycler to discharge the high voltage battery to at least a first preselected state of charge, and the controller delivers a second recharge control signal to the battery cycler following discharge of the high voltage battery, the recharge control signal causing the battery cycler to recharge the high voltage battery to at least a second preselected state of charge greater than the first state of charge.
8. The apparatus of claim 1 , wherein the battery cycler includes a physically isolated electrical contactor for selectively coupling the high voltage battery in a circuit supplying high voltage power to the high voltage battery.
9. The apparatus of claim 1 , further comprising a second controller adapted to sense faults in the operation of the battery cycler and the controller, said second controller on-board said vehicle.
10. The apparatus of claim 1 , wherein said vehicle is a hybrid vehicle.
11. A system for controlling the state of charge of an on-board battery system for a vehicle, wherein the battery system includes a low voltage battery for operating electrical systems on the vehicle and a high voltage traction battery, comprising:
a battery cycler adapted to discharge and recharge the high voltage battery, and adapted to recharge the low voltage battery, said battery cycler off-board said vehicle; and,
a first controller adapted to control the operation of the battery cycler including discharge of said high voltage battery to achieve a preselected state of charge on each of the high and low voltage batteries, said first controller onboard said vehicle;
a second controller adapted to sense faults in the operation of the battery cycler and the first controller, said second controller on-board said vehicle.
12. The system of claim 11 , wherein the battery cycler includes:
a low voltage section for recharging the low voltage battery, and, a high voltage section for periodically discharging and recharging the high voltage battery, the high voltage section including a physically isolated switch for switching a source of high voltage AC into a circuit with a load that includes the high voltage battery.
13. The system of claim 12 , wherein the battery cycler includes a first electrical connector for releasably coupling the high voltage section with a high voltage power source, and a second electrical connector for releasably coupling the battery cycler with the first controller.
14. The system of claim 12 , wherein the switch is controlled by the first controller.
15. The system of claim 12 , wherein the high voltage section includes a constant current source used to recharge the high voltage battery.
16. The system of claim 11 , wherein the battery cycler includes a load bank for use in discharging the high voltage battery.