Temperature sensitive charging of batteries with simple chargers

• US 20050253561A1
• Filed: 05/11/2004
• Published: 11/17/2005
• Est. Priority Date: 05/11/2004
• Status: Abandoned Application

• Current Assignee: Moltech Power Systems Incorporated (City of Shanghai)
• Original Assignee: Moltech Power Systems Incorporated (City of Shanghai)
• Inventors: Tibbs, Bobby Leon
• Application Number:
  US10/842,974
• Publication Number:
  US 20050253561A1
• Time in Patent Office: Days
• US Class Current: 320/150
• CPC Class Codes: H02J 7/007194 of the battery
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage

Abstract

Methods and devices are provided for charging a battery in a temperature controlled charging process using a simple voltage-controlled charger. A control circuit includes elements for increasing the apparent voltage drop in a charging circuit, including a rechargeable battery, to produce a signal to a connected voltage-controlled charger to effect a lowering of the charger supplied charging current. This increased voltage drop is initiated upon sensing battery temperatures at or above a predetermined limit. In this way, a solely voltage-controlled charger may be controlled by battery temperature.

Claims

1. A rechargeable battery comprising:

at least one interconnected electrochemical cell; and

a charging control circuit connected to the cells and comprising;

means of connecting the control circuit to a charger having only two charging contacts;

means of sensing when a cell temperature exceeds a predetermined threshold temperature; and

means of increasing, by a predetermined additional voltage, a control circuit voltage between the charger contacts when the cell temperature exceeds the threshold temperature during charging.

2. The rechargeable battery according to claim 1, and wherein:

the means of increasing voltage includes;

a means of opening a first charging circuit and allowing charging to continue through a second charging circuit having the predetermined additional voltage.

3. The rechargeable battery according to claim 2, and wherein:

the control circuit further comprises a discharge circuit for discharging the cells.

22. A powered device including a rechargeable battery according to claim 1.

23. A powered device according to claim 22, and wherein:

the powered device comprises an electric bicycle.

4. A rechargeable battery comprising:

at least one interconnected electrochemical cell having a first and second pole;

at least a first charging contact;

a thermostat in thermal communication with at least one cell and providing a first charging circuit, between the first contact and the first pole, when the thermostat is in a closed condition, and the thermostat having an electrically open condition above a set point temperature;

an incremental resistance device providing a predetermined voltage drop between the first contact and the first pole when a charging voltage is applied and providing a second charging circuit between the first charging contact and the first pole.

5. The rechargeable battery according to claim 4, and further comprising:

a discharge circuit connected to the at least one interconnected electrochemical cell.

6. The rechargeable battery according to claim 5, and wherein:

the discharge circuit is connected to allow discharge between the first charge contact and the second pole and including a means of preventing a charging current from passing through the discharge circuit.

7. The rechargeable battery according to claim 6, and wherein:

the means of preventing a charging current comprises at least one diode.

8. The rechargeable battery according to claim 4, and wherein:

the incremental resistance device comprises at least one diode.

9. The rechargeable battery according to claim 4, and wherein:

the incremental resistance device provides voltage drop of at least 1.2 volts.

10. The rechargeable battery according to claim 4, and wherein:

the set point temperature is in a range of 40 to 60 degrees C.

11. The rechargeable battery according to claim 10, and wherein:

the set point temperature is 45 degrees C.

12. The rechargeable battery according to claim 4, and further comprising:

a resistor connected to provide heating to the thermostat in the open condition.

13. The rechargeable battery according to claim 4, and further comprising

an LED connected across the thermostat and configured to illuminate in the open condition.

14. The rechargeable battery according to claim 4, and wherein:

the thermostat is of a manually resettable design.

15. The rechargeable battery according to claim 4, and wherein:

each cell is a nickel metal hydride cell.

16. A control circuit for charging a rechargeable battery with a battery charger having only two charging contacts, the control circuit comprising

a first charging circuit configured to be connected between a battery and charger and comprising a thermostat configured to be placed in thermal communication with the battery, and the thermostat configured to open above a set point temperature;

a second charging circuit parallel to the thermostat and having an incremental resistance device.

17. The control circuit according to claim 16, and further comprising:

a discharge circuit parallel to the first charging circuit.

18. The control circuit according to claim 17, and wherein:

the discharge circuit is configured to prevent charging through the discharge circuit.

19. The control circuit according to claim 18, and wherein:

the discharge circuit includes at least one schottkey diode selected and connected to prevent charging through the discharge circuit.

20. The rechargeable battery according to claim 16, and wherein:

the set point temperature is in the range of 40 to 60 degrees C.

21. The rechargeable battery according to claim 20, and wherein:

the set point temperature is 45 degrees C.

24. A method of charging a battery with a battery charger that provides voltage dependent charging current, the method comprising:

connecting a battery to a battery charger with only two electrical contacts;

operating the charger to provide charging current to the battery;

when a battery temperature is above a predetermined threshold temperature, adding a predetermined voltage drop between the charger and the battery to reduce the charge current.