Systems, methods and devices for adaptable battery charging

Patent metadata

Field	Value
Publication number	US-2016301226-A1
Application number	US-201514681810-A
Country	US
Kind code	A1
Filing date	Apr 8, 2015
Priority date	Apr 8, 2015
Publication date	Oct 13, 2016
Grant date	—

Abstract

Because a rechargeable battery has an increased number of uses (e.g., cycles), the battery's internal impedance can increase and the efficiency of the battery can become degraded. This internal resistance can cause cutoff voltage thresholds and cutoff current thresholds to prematurely stop a phase of battery charging, as these cutoff values can be based on low-cycle count batteries. New cutoff values can, instead, be based on battery impedance. Use of an adjusted cutoff current threshold during a constant voltage cycle can increase the capacity of high-cycle count batteries. Use of an adjusted cutoff voltage threshold in step charging can increase the charging speed of high-cycle count batteries. These increases in efficiency by using adjusted cutoff values can increase as the battery is further high-cycle count, in comparison with low-cycle count cutoff values used with high-cycle count batteries.

First claim

1 . A charging system for charging a battery comprising:
memory configured to store an open circuit voltage (OCV) of a low-cycle count battery; a sensor configured to determine an impedance of the battery; and a controller configured to: determine a first cutoff voltage threshold of a first constant current operation in a step charging of the battery based at least in part on the determined impedance of the battery and the stored OCV; and cause a power source to provide a first constant current until the first cutoff voltage threshold is reached.

2 . The charging system of claim 1 , wherein the controller is further configured to:
determine a second cutoff voltage threshold of a second constant current operation in the step charging of the battery based at least in part on the determined impedance of the battery and the stored OCV; and cause the power source to provide a second constant current until the second cutoff voltage threshold is reached.

3 . The charging system of claim 2 , wherein the controller is further configured to cause the power source to provide a constant voltage between the first constant current and the second constant current.

4 . The charging system of claim 3 , wherein to provide the constant voltage between the first constant current and the second constant current further comprises to hold the first cutoff voltage threshold until current delivered to the battery reaches the second constant current.

5 . The charging system of claim 1 , wherein after a final cutoff voltage threshold has been reached in a set of constant current step operations, the controller is further configured to provide a constant voltage to the battery until a cutoff current threshold is reached.

6 . The charging system of claim 1 , wherein the controller is further configured to dynamically adjust a constant current and a cutoff voltage threshold during step charging of the battery.

7 . The charging system of claim 1 , further comprising a bus between the power source and the controller configured to carry messages from the controller to the power source that cause the power source to provide a constant current to the battery.

8 . The charging system of claim 1 , wherein the battery is a lithium-ion (Li-ion) battery.

9 . A method of charging a battery comprising:
storing an initial open circuit voltage (OCV) of a fully charged rechargeable power source; determining a revised cutoff current threshold during constant voltage charge based at least in part on an indication that a OCV of a rechargeable power source has reached the initial OCV; charging the rechargeable power source at a constant current until a cutoff voltage threshold is reached; and charging the rechargeable power source at a constant voltage until the revised cutoff current threshold is reached.

10 . The method of claim 9 , wherein the revised cutoff current threshold is lower than a cutoff current threshold of a low-cycle count rechargeable power source at room temperature.

11 . The method of claim 9 , wherein determining the revised cutoff current threshold further comprises counting a number of cycles and retrieving a cutoff current threshold from a table that corresponds to the number of cycles.

12 . The method of claim 9 , wherein determining the revised cutoff current threshold further comprises measuring temperature and retrieving a cutoff current threshold from a table that corresponds to the temperature.

13 . The method of claim 9 , wherein determining the revised cutoff current threshold further comprises estimating an OCV of the rechargeable power source, determining an impedance of the rechargeable power source and calculating the revised cutoff current threshold based at least in part on the initial OCV.

14 . A method of charging a battery comprising:
storing an initial charge time of a fully charged battery; determining a revised cutoff current threshold during constant voltage charge based at least in part on matching a charge time of the battery to the initial charge time; causing the battery to charge at a constant current until a cutoff voltage threshold is reached; and causing the battery to charge at a constant voltage until the revised cutoff current threshold is reached.

15 . The method of claim 14 , wherein the revised cutoff current threshold is lower than a cutoff current threshold of a low-cycle count battery at room temperature.

16 . The method of claim 14 , wherein causing the battery to charge at the constant current further comprises transmitting a first message to a charger to charge the battery at the constant current; and
wherein causing the battery to charge at the constant voltage further comprises transmitting a second message to the charger to charge the battery at the constant voltage.

17 . The method of claim 14 , wherein determining the revised cutoff current threshold during constant voltage charge further comprises determining the revised cutoff current threshold based at least in part on battery temperature.

18 . The method of claim 14 , wherein determining the revised cutoff current threshold further comprises measuring a temperature and a number of cycles and retrieving a cutoff current threshold from a table that corresponds to the temperature and the number of cycles.

19 . A system for adaptive charging comprising:
a controller; a sensor configured to sense a voltage of a rechargeable power source; a bus interface between the controller and a charging system coupled to the rechargeable power source; the controller configured to:
receive measurements from the sensor;
estimate an open circuit voltage (OCV) of the rechargeable power source based at least in part on measurements from the sensor;
revise a current threshold based at least in part on the estimated OCV; and
communicate with the charging system over the bus interface to dynamically adjust a constant current of a constant current source and to approximately maintain a current below the current threshold associated with the estimated OCV to the rechargeable power source during a charging of the rechargeable power source.

20 . The system of claim 19 , wherein to receive measurements from the sensor further comprises to monitor measurements from the sensor;
wherein to estimate the OCV of the rechargeable power source further comprises to keep the estimate of the OCV updated based at least in part on the monitoring of the measurements; wherein to revise the current threshold based at least in part on the estimated OCV further comprises to update the current threshold when the estimated OCV exceeds an OCV threshold; wherein to communicate with the charging system over the bus interface to dynamically adjust the constant current of the constant current source further comprises to communicate the updated current threshold to the charging system after the current threshold is updated.

21 . The system of claim 19 , further comprising memory to store an undegraded OCV of an undegraded rechargeable power source.

22 . The system of claim 19 , wherein the bus interface is a system management bus (SMBUS) or I2C interface.

23 . The system of claim 22 , further comprising the charging system.

24 . The system of claim 23 , further comprising a portable computer, cell phone, tablet or drone that comprises the charger.

25 . The system of claim 19 , wherein after a final cutoff voltage threshold has bee

Assignees

• Intel Corp

Inventors

• Matsumura Naoki
• Ji Gang
• Fritz Brian C

Classifications

• H02J7/61

  against overcharge · CPC title

• H02J7/42

  with electronic devices having internal batteries, e.g. mobile phones · CPC title

• H02J7/96

  in response to battery voltage · CPC title

• H02J7/60 Primary

  including safety or protection arrangements · CPC title

• H02J7/00

  Circuit arrangements for charging or discharging batteries or for supplying loads from batteries · CPC title