Abstract:
Some embodiments of the present invention provide a system that adaptively charges a battery, wherein the battery is a lithium-ion battery which includes a transport-limiting electrode governed by diffusion, an electrolyte separator and a non-transport-limiting electrode. During operation, the system determines a lithium surface concentration at an interface between the transport-limiting electrode and the electrolyte separator based on a diffusion time for lithium in the transport-limiting electrode. Next, the system calculates a charging current or a charging voltage for the battery based on the determined lithium surface concentration. Finally, the system applies the charging current or the charging voltage to the battery.
Abstract:
The disclosed embodiments provide a system that manages use of a battery in a portable electronic device. During operation, the system provides a charging circuit for converting an input voltage from a power source into a set of output voltages for charging the battery and powering a low-voltage subsystem and a high-voltage subsystem in the portable electronic device. Upon detecting discharging of the battery in a low-voltage state, the system uses the charging circuit to directly power the low-voltage subsystem from a battery voltage of the battery and up-convert the battery voltage to power the high-voltage subsystem.
Abstract:
Some embodiments of the present invention provide a system that estimates a state of charge for a battery. During operation, while the battery is relaxing toward a fully rested state, the system determines if a modified state of charge of the battery is substantially consistent with a predetermined decay pattern. If so, the system estimates the state of charge of the battery as a value of the modified state of charge determined at the time when the consistency is observed. Otherwise, the system continues monitoring the modified state of charge of the battery. In one embodiment, the predetermined decay pattern is a single exponential decay. After estimating the state of charge of the battery, the system may determine an uncertainty of the estimated state of charge. More specifically, the system can estimate the uncertainty as substantially equal to a fraction of the difference between the value of the modified state of charge and the value of the voltage-based state of charge at the time when the consistency is observed.
Abstract:
The disclosed embodiments provide a system that manages use of a battery in a portable electronic device. During operation, the system obtains a voltage of the battery and a state-of-charge of the battery and calculates an effective C-rate of the battery using the voltage and the state-of-charge. Next, the system uses the effective C-rate to estimate an inaccessible capacity of the battery. Finally, the system manages use of the battery with the portable electronic device based on the inaccessible capacity.