LOW TEMPERATURE CHARGING OF LI-ION CELLS

• US 20110012562A1
• Filed: 09/30/2009
• Published: 01/20/2011
• Est. Priority Date: 07/17/2009
• Status: Active Grant

• Current Assignee: Tesla Inc.
• Original Assignee: Tesla Motors Incorporated (Tesla Inc.)
• Inventors: Paryani, Anil
• Granted Patent: US 8,552,693 B2
• Time in Patent Office: Days
• US Class Current: 320/152
• CPC Class Codes: H02J 7/007192 in response to temperature
• CPC Class Codes: H02J 7/007194 of the battery
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage

Abstract

A battery cell charging system, including a charger and a controller, for low-temperature (below about zero degrees Celsius) charging a lithium ion battery cell, the battery cell charging system includes: a circuit for charging the battery cell using an adjustable voltage charging-profile to apply a charging voltage and a charging current to the battery cell wherein the adjustable voltage charging-profile having: a non-low-temperature charging stage for charging the battery cell using a charging profile adapted for battery cell temperatures above about zero degrees Celsius; and a low-temperature charging stage with a variable low-temperature stage charging current that decreases responsive to a battery cell temperature falling below zero degrees Celsius.

Claims

1. A battery cell charging system, including a charger and a controller, for low-temperature (below about zero degrees Celsius) charging a lithium ion battery cell, the battery cell charging system comprising:

a circuit for charging the battery cell using an adjustable voltage charging-profile to apply a charging voltage and a charging current to the battery cell wherein said adjustable voltage charging-profile includes;

a non-low-temperature charging stage for charging the battery cell using a charging profile adapted for battery cell temperatures above about zero degrees Celsius; and

a low-temperature charging stage with a variable low-temperature stage charging current that decreases responsive to a battery cell temperature falling below zero degrees Celsius.

2. A battery cell charging system for low-temperature (below about zero degrees Celsius) charging a lithium ion battery cell, the battery cell charging system comprising:

a circuit for charging the battery cell using a variable charge-profile to apply a charging voltage and a charging current to the battery cell wherein said charge-profile is determined responsive to an imaginary R_Bad resistance included in series with an DCR resistance of a DC model for the battery cell wherein said R_Bad is a function including a component responsive to a battery cell temperature less than about zero degrees Celsius such that V_cell is about equal to a maximum battery cell voltage minus charging current times R_Bad.

3. A battery cell charging method for low-temperature (below about zero degrees Celsius) charging a lithium ion battery cell, the battery cell charging method comprising:

(a) applying, to the battery cell when a temperature of the battery cell is above about zero degrees Celsius, a non-low-temperature charging profile; and

(b) applying, to the battery cell when a temperature of the battery cell is below about zero degrees Celsius, a variable low-temperature stage charging current that decreases responsive to a battery cell temperature falling below zero degrees Celsius.

4. A battery cell charging method for low-temperature (below about zero degrees Celsius) charging a lithium ion battery cell, the battery cell charging method comprising:

(a) applying, responsive to a charge-profile, a varying charging voltage and a varying charging current to the battery cell wherein said charge-profile is determined responsive to an imaginary R_Bad resistance included in series with an DCR resistance of a DC model for the battery cell wherein said R_Bad is a function including a component responsive to a battery cell temperature less than about zero degrees Celsius such that V_cell is about equal to a maximum battery cell voltage minus charging current times R_Bad.