In-situ battery health detector and end-of-life indicator
Some embodiments provide a system that monitors a battery in a portable electronic device. During operation, the system applies a pulse load to the battery and determines an impedance of the battery by measuring a voltage of the battery during the pulse load. Next, the system assesses a health of the battery based on the impedance. Finally, the system uses the assessed health to manage use of the battery in the portable electronic device.
1. A system for monitoring a battery in a portable electronic device, comprising:
a load-generating apparatus configured to apply a pulse load to the battery;
a monitoring apparatus configured to determine an impedance of the battery by measuring a voltage of the battery during the pulse load; and
a management apparatus configured to:
assess a health of the battery based on the impedance by analyzing a linearity of the impedance of the battery for at least two separate charge-discharge cycles performed on the battery; and
use the assessed health to manage use of the battery in the portable electronic device.
2. The system of claim 1 , wherein determining the impedance of the battery involves:
measuring the voltage of the battery in a fully charged state;
calculating a drop in the voltage after the pulse load is applied; and
dividing the drop in the voltage by a current of the pulse load.
3. The system of claim 1 , wherein a lack of linearity corresponds to degradation in the battery.
4. The system of claim 1 , wherein using the assessed health to manage use of the battery in the portable electronic device involves at least one of:
adjusting a charge voltage for the battery;
notifying a user of the portable electronic device of an end-of-life for the battery; and
isolating a cell in the battery.
5. The system of claim 4 , wherein adjusting the charge voltage for the battery involves:
decreasing the charge voltage to extend a cycle life of the battery and to control cell swelling within the battery.
6. The system of claim 4 , wherein adjusting the charge voltage for the battery involves:
stopping charging of the battery at the end-of-life for the battery.
7. A portable electronic device, comprising:
a battery;
a set of components powered by the battery;
a charger configured to apply a pulse load to the battery;
a monitoring apparatus configured to determine an impedance of the battery by measuring a voltage of the battery during the pulse load; and
a management apparatus configured to:
assess a health of the battery based on the impedance by analyzing a linearity of the impedance of the battery for at least two separate charge-discharge cycles performed on the battery; and
use the assessed health to manage use of the battery in the portable electronic device.
8. The portable electronic device of claim 7 , wherein determining the impedance of the battery involves:
measuring the voltage of the battery in a fully charged state;
calculating a drop in the voltage after the pulse load is applied; and
dividing the drop in the voltage by a current of the pulse load.
9. The portable electronic device of claim 7 , wherein a lack of linearity corresponds to degradation in the battery.
10. The portable electronic device of claim 7 , wherein using the assessed health to manage use of the battery in the portable electronic device involves at least one of:
adjusting a charge voltage for the battery;
notifying a user of the portable electronic device of an end-of-life for the battery; and
isolating a cell in the battery.
11. The system of claim 10 , wherein adjusting the charge voltage for the battery involves:
decreasing the charge voltage to extend a cycle life of the battery and to control cell swelling within the battery.
12. The system of claim 10 , wherein adjusting the charge voltage for the battery involves:
stopping charging of the battery at the end-of-life for the battery.