Patent Application
20060226812
This invention relates generally to battery charging, and more particularly to an algorithm and system for improving battery cycle life during extended battery charging.
Maintaining a battery at full charge for an extended period of time adversely affects cycle life capacity performance. The adverse effect of elevated temperature on battery cycle life is also well known. A common practice among users of charging devices is to leave the battery in the charger for an extended period of time, well beyond the time of a completed charge. Unfortunately, such practice is detrimental to the cycle life of the battery since many chargers continue to charge again after a complete charge after the battery falls below a maximum charge voltage threshold. Such scenario fails to preserve the battery cycle life performance of a battery particularly when the battery remains in a charger for an extended period of time.
Embodiments in accordance with the present invention can provide a system, method or algorithm which can dynamically adjust the maximum charge voltage (Vmax, typically 4.2V) based on a length of time that a battery is left in a charger and held at Vmax and/or by a number of recharge cycles to the battery. In addition, temperature can be measured and taken into account to adjust Vmax accordingly. For example, at higher temperatures, Vmax is reduced to minimize the thermal effect on cycle life capacity.
In a first embodiment of the present invention, a battery charging method can include the steps of setting a maximum charge voltage for a battery and dynamically adjusting the maximum charge voltage for the battery based on at least one among an amount of time the battery is maintained at the maximum charge voltage and an amount of cycles the battery is charged to the maximum charge voltage. The method can further include the step of measuring a temperature of the battery and further dynamically adjusting the maximum charge voltage for the battery based on the temperature of the battery. Such technique can help maintain the battery at an acceptable charge level below the maximum charge voltage while minimizing cycle life effects of elevated voltage and temperature. In one embodiment, the method can involve setting a threshold for one among a counter and a timer and clearing at least one among the counter and the timer once a battery is removed or placed into a charger using the method. Furthermore, the method can also include the step of updating at least one among a counter and a timer each time after a charge is complete.
In a second embodiment of the present invention, another battery charging method can include the steps of setting a maximum charge voltage for a battery, setting a threshold for a timer or counter, charging the battery, incrementing a timer or counter each time when charging of the battery is complete, charging the battery again if a battery voltage for the battery falls below a recharge voltage threshold and the timer or counter fails to exceed the (timer or counter) threshold, and adjusting the maximum charge voltage before charging the battery again if the battery voltage for the battery falls below the recharge voltage threshold and the timer or counter exceeds the threshold. The method can further include the step of measuring a temperature if the timer or counter exceeds the threshold and adjusting the maximum charge voltage based on a timer or counter value and the temperature measured or alternatively adjusting the maximum charge voltage based on just a timer or counter value measured. The method can further include the step of clearing at least one among the timer and the counter before a first charge of the battery.
In a third embodiment of the present invention, a battery charging system can include a charger coupled to at least one among a timer and a counter and a processor coupled to the charger. The processor can be programmed to set a maximum charge voltage for a battery and dynamically adjust the maximum charge voltage for the battery based on at least one among an amount of time the battery is maintained at the maximum charge voltage and an amount of cycles the battery is charged to the maximum charge voltage. The processor can also clear at least one among a timer and a counter before a charge of the battery. The processor can be further programmed to measure a temperature of the battery, particularly if at least one among a timer or a counter exceeds a threshold value. In this regard, the processor can further be programmed to dynamically adjust the maximum charge voltage for the battery based on at least one among a timer value, a counter value and the temperature of the battery measured. Note, the processor can also be programmed to maintain the battery at an acceptable charge level below the maximum charge voltage while minimizing cycle life effects of elevated voltage and temperature.
Other embodiments, when configured in accordance with the inventive arrangements disclosed herein, can include a system for performing and a machine readable storage for causing a machine to perform the various processes and methods disclosed herein.
While the specification concludes with claims defining the features of embodiments of the invention that are regarded as novel, it is believed that the invention will be better understood from a consideration of the following description in conjunction with the figures.
When a battery is left in an existing conventional charger for an extended period of time, the conventional charger will continue to recharge the battery each time the battery voltage drops below a (recharge) voltage threshold or at pre-set time interval (or the conventional charger can discontinue charging causing a unacceptable capacity level). Referring to
Referring to
By dynamically adjusting the Vmax charge voltage based on the amount of time the battery is being maintained at the Vmax level and/or the amount of cycles the battery is charged to the Vmax threshold, the algorithm or method 20 is able to determine that the battery is an extended charged battery and can in turn dynamically adjust the Vmax threshold based on the aforementioned information. In addition, the method 20 can use the temperature that the battery is being charged at. In this fashion, the algorithm or method 20 can maintain the battery at an acceptable charge level while minimizing the cycle life affects of elevated voltage and temperature.
Referring to
The charging system 102 includes, for example, a conventional regulation circuit (not shown) with conventional charge pumps if needed. The charging system 102 is coupled to the cells 104 for supplying an adjustable source voltage and/or source current for charging said cells 104 in accordance with the embodiments disclosed herein. To enable charging of the battery cells 104, a charger 103 is coupled to the charging system 102 to enabling charging in accordance with an algorithm or method 20 as described in the embodiments described above. Once the charger 103 and/or battery cells 104 are removed, charging of the battery cells 104 is done.
In a supplemental embodiment, the device 100 can include a conventional wireless transceiver 108 for exchanging messages with a communication system, a conventional display 110 for conveying interactive images to a user of the device 100, an audio system 112 for conveying audible signals to the user, and a conventional memory 114 for storage. The device 100 can further include a temperature sensor 105 to enable the measurement of the temperature of the battery. This embodiment can represent, for instance, a cell phone operating according to the present invention.
In light of the foregoing description, it should be recognized that embodiments in accordance with the present invention can be realized in hardware, software, or a combination of hardware and software. A network or system according to the present invention can be realized in a centralized fashion in one computer system or processor, or in a distributed fashion where different elements are spread across several interconnected computer systems or processors (such as a microprocessor and a DSP). Any kind of computer system, or other apparatus adapted for carrying out the functions described herein, is suited. A typical combination of hardware and software could be a general purpose computer system with a computer program that, when being loaded and executed, controls the computer system such that it carries out the functions described herein.
In light of the foregoing description, it should also be recognized that embodiments in accordance with the present invention can be realized in numerous configurations contemplated to be within the scope and spirit of the claims. Additionally, the description above is intended by way of example only and is not intended to limit the present invention in any way, except as set forth in the following claims.
