Electricity: battery or capacitor charging or discharging – Battery or cell discharging – With charging
Reexamination Certificate
2001-02-22
2002-07-23
Tso, Edward H. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell discharging
With charging
Reexamination Certificate
active
06424122
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to battery charging control units and methods for controlling battery charging. More specifically, the present invention relates to a battery charging control unit for batteries used, for instance, for an electric vehicle, and a method for controlling the charging of such batteries.
2. Description of Related Art
In general, processes of charging, discharging, and recharging batteries are repeated when batteries are used. If the batteries are used for a certain period of time and these processes of charging and discharging are repeated a considerable number of times, the level of a full charge, i.e., the level at which the batteries are a fully charged to their maximum charging capacity, as compared with the initial level of full charge of the batteries, will decrease.
If this decrease in the charging capacity is caused temporarily by such factors as memory effect, it is known that the batteries can be restored to some extent by carrying out a supplemental charging (i.e., a complete charging/discharging) of the batteries.
As disclosed in the Japanese Unexamined Patent Application, First Publication No. 62-260531, for instance, the decrease in the charging capacity of the batteries can be restored by carrying out a supplemental charging process (or an even charging process) each predetermined number of times that the battery is charged.
However, among the environments in which the battery is used, there are cases in which, depending on the condition of the battery, supplemental charging of the batteries should not be carried out. In particular, when the battery is installed in an electric automobile, for example, the environments in which it is used may vary drastically. The batteries may be used in a harsh temperature environment wherein the temperature of the batteries reaches more than 40° C. during summer and less than −10° C. during winter.
Also, when batteries are in a high temperature environment, there is a danger that the batteries may be damaged by the supplemental charging process because in such an environment the charging current may be consumed in generating heat that increases the temperature of the batteries rather than being used to charge the batteries. Moreover, since a certain amount of the charging current is consumed for generating heat, the electric power is wasted and is economically ineffective.
In consideration of the above, an object of the present invention is to provide a battery charging control unit which is capable of eliminating the problem of the insufficient charging capacity of batteries by carrying out a supplemental charging process reliably at a suitable timing so that a highly efficient state of the batteries may be maintained and the lifetime thereof may be extended.
SUMMARY OF THE INVENTION
The present invention provides a battery charging control unit which controls the electric power from a power source and supplies it to a battery via a charger, comprising: a charging capacity insufficiency detection unit which detects an insufficiency in charging capacity of the battery based on the previous charging condition of the battery, the charging capacity insufficiency detection unit being capable of storing the detected insufficiency in the charging capacity of the battery; a charging capacity restoring determination unit which, after the charging capacity insufficiency detection unit detects an insufficiency in charging capacity of the battery, determines if the insufficiency in charging capacity of the battery will be restored by carrying out a supplemental charging process for the battery; and a supplemental charging unit which carries out the supplemental charging process for the battery if the charging capacity insufficiency detection unit detects an insufficiency in the charging capacity of the battery and the charging capacity restoring determination unit determines the insufficiency in charging capacity of the battery will be restored by the supplemental charging process.
As shown in
FIG. 8
, the restoring of a battery having a charging capacity insufficiency carried out by a supplemental charging process is confirmed to be effective if such a charging operation is performed after the temperature of the battery has been lowered, for instance, to an ordinary temperature. In consideration of this fact, the above battery charging control unit according to an embodiment of the invention has a structure capable of reliably restoring a battery having a charging capacity insufficiency by performing a suitable supplemental charging operation.
Specifically, the charging capacity insufficiency detection unit of the above battery charging control unit stores the charging condition (or state) of the battery in the previous charging operations in memory and carries out a supplemental charging operation based on the data of the previous charging condition stored in the memory. Also, the charging capacity restoring determination unit determines if the insufficiency in charging capacity of the battery will be restored by carrying out a supplemental charging process for the battery. This is because the restoring of the battery having a charging capacity insufficiency is difficult even with the supplemental charging operation if the temperature is high, as mentioned above, and the charging capacity restoring determination unit determines to carry out a supplemental charging process by the supplemental charging unit only when the restoring of the battery by the supplemental charging operation may be expected based on the battery temperature or the outside air temperature.
That is, the supplemental charging process is carried out only when the charging capacity insufficiency is detected and the restoring of battery is expected. Accordingly, it becomes possible to avoid performing a supplemental charging process when unnecessary. Also, harmful effects to the batteries, such as a temperature increase thereof due to the supplemental charging process or the waste of charging time and energy, may be avoided.
Moreover, since the charging capacity insufficiency detection unit only detects and stores in memory the generation of charging capacity insufficiency and does not carry out a supplemental charging process if the charging capacity restoring determination unit determines that the restoring of the battery is not expected, i.e., the supplemental charging process is carried out only when the restoring of battery is expected, and thus it becomes possible to carry out the supplemental charging process reliably.
Further, problems associated with a conventional periodic supplemental charging process, in which the process may be carried out unnecessarily, may be eliminated, simply resulting in an increase in the temperature of batteries that may shorten their life.
In accordance with another aspect of the invention, the charging capacity restoring determination unit determines if the battery will be restored by the supplemental charging process based on at least one of the battery temperature, and the outside air temperature.
According to the above battery charging control unit, since the charging capacity restoring determination unit determines if the battery will be restored by the supplemental charging process based on at least one of a battery temperature, and an outside air temperature, reliably carrying out the supplemental charging process to restore the battery when the restoring thereof is expected becomes possible.
Also, causing harmful effects to the battery, which may occur if a supplemental charging process is carried out when the temperature of battery or outside air is extremely high, may be avoided. Moreover, saving the time and energy that would be wasted if an unnecessary supplemental charging operation is performed becomes possible.
In yet another aspect of the invention, a battery charging control unit further includes: an integrated calendar, wherein the charging capacity restoring determination unit determines if the battery will be restored by the s
Ishikura Takashi
Mita Yoshinori
Okamoto Kazuhisa
Watanabe Kazunori
Watanabe Kenji
Arent Fox Kintner & Plotkin & Kahn, PLLC
Honda Giken Kogyo Kabushiki Kaisha
Tibbits Pia
Tso Edward H.
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