TWI879070B - Battery module and method for extending battery life thereof - Google Patents

Abstract

A battery module and a method for extending battery life thereof are provided. The method for extending battery life is applied to a battery management system, which controls a charger to charge a battery pack. Before the battery pack is charged, after setting a target charge value of the battery pack according to a battery health status of the battery pack, enter a constant current charging mode, and let the charger start charging to the battery pack. Next, calculate the charged value of the battery pack, and when the charged value is greater than the target charge value, the constant current charging mode is terminated. In this way, the aging status of the battery is estimated before charging, and different life extension strategies are adopted to dynamically change the target charge value of the battery. Therefore, the full capacity can be gradually increased according to the aging degree to extend the battery life.

Description

Battery module and battery life extension method thereof

The present application relates to the field of batteries, and more particularly to a battery module and a method for extending the battery life thereof.

It is known that most battery life extension methods use configurable chargers, where the battery pack actively notifies the charger through communication handshakes to dynamically change the charging voltage. However, the following problems will be encountered during the charging process:

(1) Increased complexity of the charging process: Communication with the battery is required before charging can begin, which increases the design complexity of the charger and battery pack and the production cost of the charger.

(2) Unable to fine-tune: The charging voltage of the charger has accuracy issues, so the dynamic charging voltage also has voltage accuracy defects and cannot accurately fine-tune the full charge voltage.

Therefore, the present application aims at the above-mentioned troubles and proposes a battery module and a battery life extension method thereof to solve the problems arising from the prior art.

One purpose of this application is to provide a battery module and a battery life extension method thereof, which can effectively extend the battery life, slow down battery aging, and reduce production costs and design complexity.

To achieve the above-mentioned purpose, the present application provides a battery life extension method, which is applied to a battery management system (BMS) to control the charging of a battery pack by a charger through the battery management system. The battery life extension method includes the following steps: starting the charging operation, before charging the battery pack, setting the target charging capacity value of the battery pack according to the battery health status of the battery pack, entering the constant current charging mode, and allowing the charger to start charging the battery pack; calculating the charged capacity value of the battery pack; and when the charged capacity value is greater than the target charging capacity value, terminating the constant current charging mode.

In one embodiment of the present application, the target charging capacity value is one or a combination of the safe reserve capacity and the safe full charge capacity.

In one embodiment of the present application, the steps of terminating the constant current charging mode include: when the charged power value is greater than the target charged power value, setting a safe full charge voltage range according to the target charged power value, wherein the target charged power value is the safe full charge power; sensing the battery pack to obtain the voltage value; and when the voltage value is within the safe full charge voltage range, terminating the constant current charging mode.

In one embodiment of the present application, the step of terminating the constant current charging mode includes: when the charged power value is greater than the target charged power value, setting a safe full charge voltage according to the target charged power value, wherein the target charged power value is the safe full charge power, sensing the battery pack to obtain the voltage value, and terminating the constant current charging mode when the voltage value is equal to the safe full charge voltage.

In one embodiment of the present application, the step of ending the constant current charging mode further includes: notifying the charger to stop charging the battery pack through a communication handshake.

In one embodiment of the present application, the step of ending the constant current charging mode further includes: controlling the battery pack to cut off the charging circuit between the charger and the battery pack to stop the charging operation.

In one embodiment of the present application, the battery life extension method further includes starting a charging operation when the remaining power of the battery pack is equal to or less than a lower limit backup capacity or a lower limit storage voltage.

In one embodiment of the present application, the step of calculating the charged capacity of the battery pack includes: sensing the current values of the discharge circuit and the charge circuit of the battery pack, respectively calculating the discharge capacity and the charge capacity, wherein, during the charging operation, the discharge capacity is less than the charge capacity; and calculating the charged capacity value according to the discharge capacity and the charge capacity, wherein the relationship between the charged capacity values is:

In one embodiment of the present application, the target charging capacity value is inversely proportional to the battery health status.

The present application also proposes a battery module, which is connected to a load and a charger respectively, and includes a cell pack and a battery management system. The cell pack has a battery health status. The battery management system is connected to the cell pack, sets a target charging capacity value according to the battery health status, and stops charging the cell pack in a constant current charging mode when the charged capacity of the cell pack is greater than the target charging capacity value, wherein the target charging capacity value is inversely proportional to the battery health status.

In one embodiment of the present application, the battery module further includes a switch and a power calculation unit. The switch connects the cell group and the battery management system, and respectively establishes a charging loop with the charger and a discharging loop with the load. The power calculation unit is connected to the battery management system, and is used to sense the current value on the charging loop and the discharging loop, and is used to calculate the discharging power and the charging power, respectively, and obtain the charged value of the cell group.

In one embodiment of the present application, the battery management system controls the switch to cut off the charging circuit between the charger and the battery pack to stop charging.

In one embodiment of the present application, the battery management system may further include a communication module, and the communication module may notify the charger to start or stop charging the battery pack through a communication handshake.

The following examples illustrate the preferred implementation of this application, and are illustrated with accompanying drawings.

The battery life extension method of this application is applied to a battery management system, and the battery management system controls the charging of the battery pack by the charger.

Please refer to Figure 1. The battery life extension method includes the following steps: Step S100: Start the charging operation. Step S200: Before charging the battery pack, set the target charging capacity value of the battery pack according to the battery health status of the battery pack. Step S300: Enter the constant current charging mode (CC mode) to charge the battery with a fixed current, and let the charger start charging the battery pack. Step S400: Calculate the charged capacity value of the battery pack. Step S500: Determine whether the charged capacity value is greater than the target charging capacity value. If so, proceed to step S600, otherwise proceed to step S300. Step S600: End the constant current charging mode.

Generally speaking, new batteries are in a healthy state when they leave the factory. The battery state of health (SOH) can be defined as 100%, and the value of the battery state of health is the amount of electricity that can be released after charging is completed divided by the factory rated capacity. However, as the battery ages and wears out, the battery capacity and performance will gradually decrease, and the battery state of health (SOH value) will also gradually decrease.

Based on the above phenomenon, in order to extend the service life of the battery, in step S200 and step S500 of the first embodiment of the present application, the target charging capacity value is the safe reserve capacity, and the target charging capacity value is inversely proportional to the battery health status. Furthermore, the lower the battery health status value, the higher the target charging capacity (safe reserve capacity); the higher the battery health status value, the lower the target charging capacity (safe reserve capacity). Before charging the battery pack, the battery management system can set the expected charging capacity value according to the SOH value. For example, when the SOH value is 100%, the target charging capacity (safe reserve capacity) can be set to 80%; when the SOH value is 80%, the target charging capacity (safe reserve capacity) is set to 95%. The aforementioned numerical values are merely examples and are not intended to be limiting.

In step S400 of the first embodiment, the charged capacity of the battery pack is calculated by sensing the current values of the discharge circuit and the charge circuit of the battery pack to respectively calculate the discharge capacity and the charge capacity. Generally speaking, during the charging operation, the discharge capacity of the battery pack is less than the charge capacity. The charged capacity is further calculated based on the discharge capacity and the charge capacity, and the relationship between the charged capacity and the discharge capacity is as follows: .

Therefore, when the battery aging condition is not high, the above method can further monitor the battery during the charging process by setting a relatively sufficient reserve capacity to avoid the battery pack being in a fully charged and over-voltage state for a long time.

Please refer to FIG. 2 , the difference between the second embodiment and the first embodiment is that after executing step S600 , after the constant current charging mode is terminated in step S600 , step S700 is executed: determining whether the remaining power of the battery pack is equal to or less than the lower limit standby capacity or the lower limit storage voltage.

After the battery pack stops the constant current charging mode, the battery pack is in a relatively low voltage range due to self-consumption or peak load power consumption. At this time, in step S700, when the remaining power of the battery pack is reduced to the lower limit of the backup capacity or the lower limit of the storage voltage, it will return to step S100 to restart the extended life charging operation.

Therefore, the battery life extension method of the present application can prevent the battery pack from being over-discharged and thus shortening the battery life, thereby achieving the effect of extending the battery life.

Please refer to FIG. 3 . The difference between the third embodiment and the first embodiment is that the third embodiment further includes step S510 to step S530 between step S500 and step S600. When it is determined in step S500 that the charged power value is greater than the target charged power value, the following steps are performed first: Step S510: Set the safe full charge voltage range according to the target charged power value. Step S520: Sense the battery pack to obtain the voltage value. Step S530: Determine whether the voltage value is within the safe full-charge voltage range. If yes, proceed to step S600; otherwise, proceed to step S520, continue to maintain the constant current charging mode and sense the voltage value of the battery pack.

Generally speaking, a battery pack includes multiple battery cells. Due to electrochemical principles, the power of each battery cell in the same battery pack is different. Therefore, continuous charging of a battery cell with a high power will cause the battery cell to be overcharged. However, if the charging is suspended when the battery cell with a high power is fully charged, the battery cell with a low power will not be fully charged. When the power of each battery cell is different, continuous charging and discharging may cause aging of a single battery cell, thereby affecting the performance of the entire battery pack. Therefore, in the third embodiment, in step S510, the target charging power value further includes a safe full charge power. Therefore, setting the safe full charge voltage range according to the safe full charge power can further improve this problem.

Please refer to FIG. 4 , the fourth embodiment differs from the third embodiment in that step S500 and step S600 further include step S511, step S520′, and step S531.

In step S511, the safe full-charge voltage is set according to the target charging capacity value. Then, step S520' is executed to sense the battery pack to obtain the voltage value. Step S531 is further executed to determine whether the voltage value is equal to the safe full-charge voltage. When the voltage value is not equal to the safe full-charge voltage, return to step S520 to continue to maintain the constant current charging mode and sense the voltage value of the battery pack. When the voltage value of the battery pack is equal to the safe full-charge voltage, step 600 is executed to end the constant current charging mode.

In step S511, the target charging capacity is the safe full charge capacity. For example, assuming that the rated voltage of a brand new battery pack is 4V, the full charge voltage is generally set at 3.8V. In this embodiment, the safe full charge voltage can be set to 3.6V through step S511. The target is to stop charging when the voltage of the battery pack reaches 3.6V. However, if the voltage is judged alone, it is impossible to determine whether the charged capacity is sufficient. Therefore, through step S200 to step S500, it is first determined that the charged value of the battery pack is greater than the safe reserve capacity, and then after further determining that the voltage value of the battery pack is equal to the safe full-charge voltage, the safe reserve capacity and the safe full-charge capacity of the battery pack can be set when the battery is in a better health state, so that the battery pack will not be in an over-high voltage state for a long time when it is fully charged, thereby having the effect of extending the battery life.

Please refer to FIG. 5 . In one embodiment, the battery module 10 of the present application is connected to a load 20 and a charger 30 respectively, and the battery module 10 includes a battery pack 11 and a battery management system 12 .

The cell pack 11 has a battery health status. The battery management system 12 is connected to the cell pack 11, sets a target charging capacity value according to the battery health status, and stops charging the cell pack 11 in a constant current charging mode when the charged capacity of the cell pack 11 is greater than the target charging capacity value.

Among them, the target charging capacity value is inversely proportional to the battery health status.

In one embodiment, the battery module 10 includes a switch 13 and a power calculation unit 14 .

The switch 13 connects the cell pack 11 and the battery management system 12, and respectively establishes a charging loop with the charger 30 and a discharging loop with the load 20. The power calculation unit 14 is connected to the battery management system 12, and is used to sense the current values in the charging loop and the discharging loop, and to respectively calculate the discharging power and the charging power, and obtain the charged value of the cell pack 11. The power calculation unit 14 can be a coulomb counter.

In one embodiment, the battery management system 12 can control the switch 13 to cut off the charging circuit between the charger 30 and the battery pack 11 to stop charging.

In one embodiment, the battery management system 12 may further include a communication module 121. The communication module 121 may notify the charger 30 to start or stop charging the battery pack 11 through a communication handshake.

In summary, the battery module and battery life extension method described in this application can estimate the battery aging status by monitoring the voltage and charging and discharging behavior of the battery pack before charging, adopt different life extension strategies, and then dynamically change the full capacity or full voltage after the battery is fully charged. During the charging process of the battery pack, when it is found that the charging capacity has met the minimum system capacity requirement, charging can be stopped. By gradually increasing the full capacity according to the degree of aging, the battery life can be extended.

The above is only an example to illustrate the preferred implementation of this application, and is not intended to limit the scope of implementation. All simple substitutions and equivalent changes made based on the patent scope of this application and the content of the patent specification are within the scope of the patent application of this application.

S100~S700, S510~S530, S511, S520’, S531: Steps 10: Battery module 11: Cell pack 12: Battery management system 121: Communication module 13: Switch 14: Power calculation unit 20: Load 30: Charger

FIG1 is a flow chart of the first embodiment of the battery life extension method of the present application. FIG2 is a flow chart of the second embodiment of the battery life extension method of the present application. FIG3 is a flow chart of the third embodiment of the battery life extension method of the present application. FIG4 is a flow chart of the fourth embodiment of the battery life extension method of the present application. FIG5 is a block diagram of an embodiment of the battery module of the present application.

S100~S600: Steps

Claims (14)

A battery life extension method is applied to a battery management system, and controls a charger to charge a battery pack through the battery management system. The battery life extension method includes the following steps: Start a charging operation; Before charging the battery pack, set a target charging capacity value of the battery pack according to a battery health status of the battery pack, enter a constant current charging mode, and allow the charger to start charging the battery pack; In the constant current charging mode, calculate a charged capacity value of the battery pack; and When the charged capacity value is greater than the target charging capacity value, end the constant current charging mode. A battery life extension method as described in claim 1, wherein the target charging capacity value is a safe reserve capacity. A battery life extension method as described in claim 1, wherein the target charging capacity value is one or a combination of a safe standby capacity and a safe full charge capacity. The battery life extension method as described in claim 3, wherein the step of terminating the constant current charging mode includes: When the charged amount value is greater than the target charged amount value, setting a safe full charge voltage range according to the target charged amount value, wherein the target charged amount value is the safe full charge amount; Sensing the battery pack to obtain a voltage value; and When the voltage value is within the safe full charge voltage range, terminating the constant current charging mode. The battery life extension method as described in claim 3, wherein the step of terminating the constant current charging mode includes: When the charged power value is greater than the target charged power value, setting a safe full charge voltage according to the target charged power value, wherein the target charged power value is the safe full charge power; Sensing the battery pack to obtain a voltage value; and When the voltage value is equal to the safe full charge voltage, terminating the constant current charging mode. The battery life extension method as described in claim 1, wherein the step of terminating the constant current charging mode further includes: Notifying the charger to stop the charging operation of the battery pack through communication handshake. The battery life extension method as described in claim 1, wherein the step of terminating the constant current charging mode further includes: Controlling the battery pack to cut off a charging circuit between the charger and the battery pack to stop the charging operation. The battery life extension method as described in claim 1 further comprises the following steps: When the remaining power of the battery pack is equal to or less than a lower limit backup capacity or a lower limit storage voltage, the charging operation is started. The battery life extension method as claimed in claim 1, wherein the step of calculating the charged capacity value of the battery pack comprises: sensing the current values of a discharge circuit and a charge circuit of the battery pack, respectively calculating a discharge capacity and a charge capacity, wherein, during the charging operation, the discharge capacity is less than the charge capacity; and calculating the charged capacity value according to the discharge capacity and the charge capacity, wherein the relationship between the charged capacity values is: . A battery life extension method as described in claim 1, wherein the target charging capacity value is inversely proportional to the battery health status. A battery module is connected to a load and a charger respectively, and the battery module comprises: a battery pack having a battery health status; and a battery management system connected to the battery pack, setting a target charging capacity value according to the battery health status before charging the battery pack, and entering a constant current charging mode, calculating a charged capacity value of the battery pack in the constant current charging mode, and terminating the constant current charging mode and stopping charging of the battery pack when the charged capacity of the battery pack in the constant current charging mode is greater than the target charging capacity value, wherein the target charging capacity value is inversely proportional to the battery health status. The battery module as described in claim 11, wherein the battery module further comprises: a switch connecting the battery pack and the battery management system, and establishing a charging loop with the charger and a discharging loop with the load respectively; and a power calculation unit connected to the battery management system, used to sense the current values on the charging loop and the discharging loop, and to calculate a discharging power and a charging power respectively, so as to obtain the charged power value of the battery pack. A battery module as described in claim 12, wherein the battery management system controls the switch to cut off the charging circuit between the charger and the battery pack to stop charging. The battery module as described in claim 11, wherein the battery management system further comprises: A communication module, which notifies the charger to start or stop charging the battery pack through a communication handshake.

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