JP2008005693A - Battery device - Google Patents

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Publication number
JP2008005693A
JP2008005693A JP2007131894A JP2007131894A JP2008005693A JP 2008005693 A JP2008005693 A JP 2008005693A JP 2007131894 A JP2007131894 A JP 2007131894A JP 2007131894 A JP2007131894 A JP 2007131894A JP 2008005693 A JP2008005693 A JP 2008005693A
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battery
voltage
secondary battery
charging
terminal voltage
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Hirobumi Hirooka
博文 廣岡
Hitoshi Hamaguchi
仁志 浜口
Shinichi Itagaki
真一 板垣
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Sanyo Electric Co Ltd
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Sanyo Electric Co Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery device capable of sufficiently utilizing the function of a battery cell constituting a secondary battery, while ensuring safety as the secondary battery, even when overcharge protection function operates. <P>SOLUTION: The battery device includes a voltage detection means for detecting a terminal voltage Vbat of a secondary battery and a terminal voltage Vcell of each battery cell; a charge control means which controls charging to the secondary battery, according to the terminal voltage Vbat of the secondary battery; and a variation detecting means for determining variation in battery characteristics among a plurality of battery cells, based on the terminal voltage Vcell of the battery cells, which reduces the charge control voltage Vcharge of the charge control means according to the maximum terminal voltage Vmax of the battery cell, when a variation among the plurality of battery cells is detected. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、複数の電池セルを直列接続した二次電池における前記電池セル間の特性のバラツキに起因する不具合を回避する機能を備えた電池装置に関する。   The present invention relates to a battery device having a function of avoiding problems caused by variations in characteristics between battery cells in a secondary battery in which a plurality of battery cells are connected in series.

複数の電池セルを直列に接続した二次電池は、通常、その充電電圧を監視しながらその充電が行われる。例えば充電装置側において二次電池の端子電圧Ｖbatを監視し、この端
子電圧Ｖbatから求められる上記各電池セル１個当たりの端子電圧Ｖcellが予め設定した
電圧に達したとき、その充電電流を減少させる等して満充電状態での充電電圧を一定化するようにしている。 A secondary battery in which a plurality of battery cells are connected in series is normally charged while monitoring its charging voltage. For example, the terminal voltage Vbat of the secondary battery is monitored on the charging device side, and when the terminal voltage Vcell per battery cell obtained from the terminal voltage Vbat reaches a preset voltage, the charging current is reduced. For example, the charging voltage in the fully charged state is made constant.

ところでリチウムイオン電池等の非水溶媒系の二次電池においては、電池セルの充電電圧Ｖcellが高くなりすぎるとその電池性能が劣化したり、また電池としての安全性が損なわれる虞がある。これ故、従来においては、例えば二次電池に対する急速充電時間を制御することで該二次電池（電池セル）に対する過充電を防止するようにしている（例えば特許文献１を参照）。また、例えば電池セルの充電電圧Ｖcellが予め設定した過充電保護電圧Ｖoverに達したときに作動して、前記二次電池に対する充放電回路を遮断する保護機能を組み込む等の対策が講じられている（例えば特許文献２を参照）。
特開平８−２０５４１８号公報 特開２００１−１２６７７２号公報 By the way, in the nonaqueous solvent type secondary battery such as a lithium ion battery, when the charging voltage Vcell of the battery cell becomes too high, the battery performance may be deteriorated, and the safety as the battery may be impaired. Therefore, conventionally, for example, the overcharge of the secondary battery (battery cell) is prevented by controlling the quick charge time for the secondary battery (see, for example, Patent Document 1). In addition, for example, measures are taken such as a protection function that is activated when the charging voltage Vcell of the battery cell reaches a preset overcharge protection voltage Vover and shuts off the charging / discharging circuit for the secondary battery. (For example, refer to Patent Document 2).
JP-A-8-205418 JP 2001-126792 A

ところで種々の手法を用いて二次電池の充電を制御しているにも拘わらずに生じる電池セルの過充電は、専ら、電池セルの特性劣化（電池寿命）に起因することが多い。しかも直列に接続した複数の電池セルの全てが一斉に特性劣化することは極めて希である。従って上述した電池セルの過充電は、複数の電池セル間における電池特性のバラツキに起因すると考えられる。   By the way, in many cases, the overcharge of the battery cell that occurs despite controlling the charging of the secondary battery using various methods is mainly caused by the deterioration of the battery cell characteristics (battery life). Moreover, it is extremely rare that all of the plurality of battery cells connected in series are deteriorated in characteristics at the same time. Therefore, it is considered that the overcharge of the battery cell described above is caused by variation in battery characteristics between the plurality of battery cells.

しかしながら、例えば直列に接続した複数の電池セルの１つが特性劣化し、これに起因して過充電が生じて過充電保護機能が作動したとしても、残りの電池セルは未だ十分に電池としての機能を有している。従って上記過充電保護機能が作動したことを以て該二次電池の安全性が低下した（安全性が保証されない）と看做し、その二次電池をそのまま使用禁止とする（廃棄する）ことは甚だ不経済である。   However, even if, for example, one of a plurality of battery cells connected in series deteriorates in characteristics and overcharge occurs due to this, the remaining battery cells still function as batteries sufficiently. have. Therefore, considering that the overcharge protection function has been activated, the safety of the secondary battery has been reduced (safety is not guaranteed), and it is imperative that the secondary battery be prohibited from use (discarded) as it is. It is uneconomical.

本発明はこのような事情を考慮してなされたもので、その目的は、電池セルの特性劣化に起因して過充電保護機能が働いた場合であっても、二次電池としての安全性を保証しながら、その二次電池に残されている電池機能を十分に利用することのできる電池装置を提供することにある。   The present invention has been made in consideration of such circumstances, and its purpose is to provide safety as a secondary battery even when an overcharge protection function is activated due to deterioration of battery cell characteristics. An object of the present invention is to provide a battery device that can fully utilize the battery function remaining in the secondary battery while guaranteeing.

上述した目的を達成するべく本発明に係る電池装置は、複数の電池セルを直列に接続した二次電池を備え、例えば電池パック化されてノート型パーソナルコンピュータ等の負荷に対するバックアップ電源装置として用いるに好適なものであって、
<ａ> 前記二次電池の端子電圧Ｖbatおよび前記各電池セルの端子電圧Ｖcellをそれぞれ
検出する電圧検出手段と、
<ｂ> 前記二次電池の端子電圧Ｖbatに応じて該二次電池に対する充電を制御する充電制御手段と、
<ｃ> 前記各電池セルの端子電圧Ｖcellから前記複数の電池セル間における電池特性のバラツキを判定するバラツキ検出手段と、
<ｄ> 前記複数の電池セル間のバラツキが検出されたとき、前記二次電池に対する過充電保護電圧を低減する制御・演算部と
を具備したことを特徴としている。 In order to achieve the above-described object, a battery device according to the present invention includes a secondary battery in which a plurality of battery cells are connected in series. For example, the battery device is formed into a battery pack and used as a backup power supply device for a load such as a notebook personal computer. Preferred,
<a> Voltage detection means for detecting the terminal voltage Vbat of the secondary battery and the terminal voltage Vcell of each of the battery cells,
<b> Charge control means for controlling charging of the secondary battery according to the terminal voltage Vbat of the secondary battery;
<c> Variation detection means for determining variation in battery characteristics among the plurality of battery cells from the terminal voltage Vcell of each of the battery cells;
<d> A control / arithmetic unit that reduces an overcharge protection voltage for the secondary battery when variation among the plurality of battery cells is detected.

或いは上記制御・演算部に代えて、
<ｅ> 前記複数の電池セル間のバラツキが検出されたとき、電池セルの最大端子電圧Ｖmaxに応じて前記充電制御手段における充電制御電圧Ｖchargeを低減する設定電圧変更手段
を具備したことを特徴としている。
ちなみに前記バラツキ検出回路は、例えば前記各電池セルの端子電圧Ｖcellを相互に比較して複数の電池セル間のバラツキを判定するように構成される。或いは前記バラツキ検出回路は、前記各電池セルの端子電圧Ｖcellが、その過充電保護電圧Ｖoverを超えるか否かをそれぞれ判定して複数の電池セル間のバラツキを判定するように構成される。そして前記設定電圧変更手段は、電池セルの最大端子電圧Ｖmaxがその過充電保護電圧Ｖoverよ
りも低くなるように前記二次電池に対する充電制御電圧Ｖchargeを変更するものとして実現される。 Alternatively, instead of the control / calculation unit,
<e> A setting voltage changing unit that reduces the charging control voltage Vcharge in the charging control unit according to the maximum terminal voltage Vmax of the battery cell when variation between the plurality of battery cells is detected is provided. Yes.
Incidentally, the variation detection circuit is configured to determine variations among a plurality of battery cells by comparing terminal voltages Vcell of the respective battery cells with each other, for example. Alternatively, the variation detection circuit is configured to determine whether or not the terminal voltage Vcell of each battery cell exceeds the overcharge protection voltage Vover to determine variation between the plurality of battery cells. The set voltage changing means is realized as changing the charging control voltage Vcharge for the secondary battery so that the maximum terminal voltage Vmax of the battery cell is lower than the overcharge protection voltage Vover.

上述した構成の電池装置によれば、二次電池を構成する直列接続された複数の電池セル間における電池特性にバラツキが生じ、例えば、これに起因して或る電池セルの端子電圧Ｖcellが過充電保護電圧Ｖlimを超えて過電圧保護機能が作動するような事態が生じても
、その後の二次電池に対する過充電保護電圧を低減するので、或いはその後の前記二次電池に対する充電電圧Ｖbatが低く抑えられるので、これによって上記特性劣化した電池セ
ルの端子電圧cellを前記過充電保護電圧Ｖlimよりも低く抑えることができる。この結果
、二次電池としての全体的な安全性を保証しながら、特性が劣化していない電池セルを有効に活用することで、二次電池としての機能を継続させることが可能となる。 According to the battery device having the above-described configuration, the battery characteristics vary among the plurality of battery cells connected in series constituting the secondary battery. For example, the terminal voltage Vcell of a certain battery cell is excessive due to this. Even if an overvoltage protection function is activated beyond the charge protection voltage Vlim, the subsequent overcharge protection voltage for the secondary battery is reduced, or the subsequent charge voltage Vbat for the secondary battery is kept low. As a result, the terminal voltage cell of the battery cell whose characteristics have deteriorated can be kept lower than the overcharge protection voltage Vlim. As a result, it is possible to continue the function as the secondary battery by effectively utilizing the battery cells whose characteristics are not deteriorated while guaranteeing the overall safety as the secondary battery.

尚、二次電池に対する充電電圧Ｖbatを低く抑えることでその充電容量が少なくなり、
この結果、二次電池の使用可能時間が短くなる。しかしこの状態で二次電池が機能している間に、該二次電池の性能が劣化した（電池寿命が近付いてきた）旨を警告表示し、これによって新しい二次電池への交換を促すようにすれば良い。 In addition, the charging capacity is reduced by keeping the charging voltage Vbat for the secondary battery low,
As a result, the usable time of the secondary battery is shortened. However, while the secondary battery is functioning in this state, a warning is displayed indicating that the performance of the secondary battery has deteriorated (the battery life is approaching), thereby prompting replacement with a new secondary battery. You can do it.

以下、図面を参照して本発明の一実施形態に係る電池装置について説明する。
図１は、ノート型パーソナルコンピュータ等の電子機器３０に装着されて、該電子機器３０のバックアップ電源として用いられる、いわゆる電池パック化された本発明の一実施形態に係る電池装置１０の概略構成を示している。この電池装置１０は、基本的には前記電子機器３０が内蔵する制御・電源部３１に接続されて充電される二次電池１を備え、充電により上記二次電池１に蓄積した電力エネルギを、前記電子機器３０の本体部であるＣＰＵやメモリ等の負荷３２に対して前記制御・電源部３１を介して供給するように構成される。 Hereinafter, a battery device according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a schematic configuration of a battery device 10 according to an embodiment of the present invention in a so-called battery pack that is mounted on an electronic device 30 such as a notebook personal computer and used as a backup power source of the electronic device 30. Show. This battery device 10 basically includes a secondary battery 1 that is connected to and charged by a control / power supply unit 31 built in the electronic device 30, and stores the electric energy stored in the secondary battery 1 by charging. The electronic device 30 is configured to be supplied via the control / power supply unit 31 to a load 32 such as a CPU or a memory which is a main body of the electronic device 30.

さてリチウムイオン電池やニッケル水素電池等からなる二次電池１は、例えば複数の電池セル２を直並列に接続して所定の電池電圧と電池容量とを確保した電池群として実現される。例えばリチウムイオン電池の満充電状態で４.２Ｖとなる電池セル２を用いる場合
には、電池セル２を３段直列に接続することで、全体として１２.６Ｖの電池電圧を有す
る二次電池として実現される。また各段の電池セル２を、それぞれ複数の電池セルを並列接続したものとすることで、必要な電気容量が確保される。 Now, the secondary battery 1 composed of a lithium ion battery, a nickel metal hydride battery or the like is realized as a battery group in which a plurality of battery cells 2 are connected in series and parallel to ensure a predetermined battery voltage and battery capacity. For example, when using a battery cell 2 that is 4.2 V in a fully charged state of a lithium ion battery, connecting the battery cells 2 in three stages in series results in a secondary battery having a battery voltage of 12.6 V as a whole. Realized. Moreover, the required electric capacity is ensured by making the battery cell 2 of each step | paragraph connect the some battery cell in parallel, respectively.

ちなみにこれらの複数の電池セル２の並列接続および直列接続は、例えば金属板やリード線からなる接続タブ３を用いて行われ、二次電池１はこれらの電池セル群を１つにまとめてパッケージ化したものとして実現される。尚、電池セル２の並列接続数や、直列接続する電池セル２の段数については、負荷２に応じて二次電池１に要求される仕様（電池電圧・電池容量）に従って定められるものであり、図１に例示する３並列・３段直列構成の二次電池に限定されないことは言うまでもない。またこのような二次電池１には、例えばその電池温度Ｔを検出する為のサーミスタ等の温度センサ４が一体に組み込まれる。   Incidentally, the plurality of battery cells 2 are connected in parallel and in series using a connection tab 3 made of, for example, a metal plate or a lead wire, and the secondary battery 1 is packaged by combining these battery cell groups into one. It is realized as The number of battery cells 2 connected in parallel and the number of battery cells 2 connected in series are determined according to the specifications (battery voltage and battery capacity) required for the secondary battery 1 according to the load 2. Needless to say, the secondary battery is not limited to the secondary battery having a three-parallel / three-stage series configuration illustrated in FIG. Also, in such a secondary battery 1, a temperature sensor 4 such as a thermistor for detecting the battery temperature T is integrally incorporated.

一方、電池装置１０は、二次電池１の充放電路に、その充放電電流Ｉを検出するための電流検出部５を備えている。この電流検出部５は、例えば上記充放電路に直列に介挿されたシャント抵抗と、このシャント抵抗の両端間に生じた電圧から前記二次電池１の充放電電流Ｉを検出するセンシングアンプとにより構成される。二次電池１の充放電路に流れる電流が充電電流であるか、或いは放電電流であるかは、上記シャント抵抗の両端間に生じる電圧の極性から判定されることは言うまでもない。   On the other hand, the battery device 10 includes a current detection unit 5 for detecting the charge / discharge current I in the charge / discharge path of the secondary battery 1. The current detection unit 5 includes, for example, a shunt resistor inserted in series in the charge / discharge path, and a sensing amplifier that detects the charge / discharge current I of the secondary battery 1 from the voltage generated between both ends of the shunt resistor. Consists of. Needless to say, whether the current flowing in the charge / discharge path of the secondary battery 1 is a charge current or a discharge current is determined from the polarity of the voltage generated across the shunt resistor.

また前記二次電池１の充放電路には、前記二次電池１の過充電阻止する為の充電制御スイッチ６と、二次電池１の過放電を阻止する為の放電制御スイッチ７とがそれぞれ設けられる。これらの制御スイッチ６,７は、例えば前記充放電路にそれぞれ直列に介挿された
２つのＰチャネル型のＭＯＳ−ＦＥＴからなる。これらの制御スイッチ（ＦＥＴ）６,７
は、後述する制御・演算部２０によりその動作が制御されるものであって、例えばそのゲートにハイレベル（Ｈ）の制御信号が印加されたときに遮断（オフ）動作して、前記二次電池１に対する充電電流または放電電流をそれぞれ遮断する機能、つまり二次電池１の充電および放電をそれぞれ禁止する役割を担う。 The charge / discharge path of the secondary battery 1 includes a charge control switch 6 for preventing overcharge of the secondary battery 1 and a discharge control switch 7 for preventing overdischarge of the secondary battery 1, respectively. Provided. These control switches 6, 7 are composed of, for example, two P-channel MOS-FETs inserted in series in the charge / discharge path. These control switches (FET) 6,7
Is controlled by a control / arithmetic unit 20, which will be described later. For example, when a high level (H) control signal is applied to the gate, the secondary / secondary operation is performed. It plays the function of blocking the charging current or discharging current for the battery 1, that is, the charging and discharging of the secondary battery 1.

さて前述した充電制御スイッチ６および放電制御スイッチ７の作動をそれぞれ制御する制御・演算部２０は、例えばマイクロプロセッサにより実現される。この制御・演算部２０は、基本的には前記二次電池１の端子電圧Ｖbat、および二次電池１を構成する前記各電池セル２の端子電圧Ｖcellをそれぞれ検出して前記各スイッチ６,７のオン・オフ動作を制御する役割を担う。また制御・演算部２０は、前述した電流検出部４にて検出される二次電池１の充放電電流Ｉを入力すると共に、前記温度センサ４を用いて温度検出部８が検出する電池温度Ｔを入力し、例えば前記二次電池１の充電容量（残容量）を管理する機能を備える。   The control / calculation unit 20 that controls the operations of the charge control switch 6 and the discharge control switch 7 described above is realized by, for example, a microprocessor. The control / arithmetic unit 20 basically detects the terminal voltage Vbat of the secondary battery 1 and the terminal voltage Vcell of each of the battery cells 2 constituting the secondary battery 1 to detect each of the switches 6 and 7. It plays a role of controlling the on / off operation of. The control / calculation unit 20 inputs the charging / discharging current I of the secondary battery 1 detected by the current detection unit 4 described above, and the battery temperature T detected by the temperature detection unit 8 using the temperature sensor 4. For example, and has a function of managing the charge capacity (remaining capacity) of the secondary battery 1.

ちなみに図１に例示する前記制御・演算部２０は、３段に直列接続された複数の電池セル２における各正極側の電圧Ｖ１,Ｖ２,Ｖ３、電流検出部４にて検出された充放電電流Ｉ、および温度検出部８にて検出された電池温度Ｔをマルチプレクサ２１を介して選択的に入力し、これをＡ／Ｄコンバータ２２を介してデジタル変換して取り込むものとなっている。これらの情報（電圧・電流・温度）の入力は、マルチプレクサ２１およびＡ／Ｄコンバータ２２のサンプリング周期に同期して、所定の周期で巡回的に行われる。そして上記複数の電池セル２の各正極電圧Ｖ１,Ｖ２,Ｖ３から、前述した二次電池１の端子電圧Ｖbat、および前記各電池セル２の端子電圧Ｖcell１,Ｖcell２,Ｖcell３をそれぞれ検出するものとなっている。   Incidentally, the control / arithmetic unit 20 illustrated in FIG. 1 includes the positive and negative voltages V1, V2, V3 in the plurality of battery cells 2 connected in series in three stages, and the charge / discharge current detected by the current detector 4. I and the battery temperature T detected by the temperature detector 8 are selectively input via the multiplexer 21 and digitally converted via the A / D converter 22 to be captured. These pieces of information (voltage, current, temperature) are input cyclically at a predetermined cycle in synchronization with the sampling cycle of the multiplexer 21 and the A / D converter 22. The terminal voltage Vbat of the secondary battery 1 and the terminal voltages Vcell1, Vcell2, Vcell3 of the battery cells 2 are detected from the positive voltages V1, V2, V3 of the plurality of battery cells 2, respectively. ing.

具体的には前記制御・演算部２０は、前記複数の電池セル２の各正極電圧Ｖ１,Ｖ２,Ｖ３から、前記二次電池１の端子電圧Ｖbat、および前記各電池セル２の端子電圧Ｖcell１,Ｖcell２,Ｖcell３を
Ｖbat＝Ｖ１
Ｖcell１＝Ｖ１−Ｖ２
Ｖcell２＝Ｖ２−Ｖ３ Ｖcell３＝Ｖ３
としてそれぞれ求めている。 Specifically, the control / arithmetic unit 20 calculates the terminal voltage Vbat of the secondary battery 1 and the terminal voltage Vcell1, of each battery cell 2 from the positive voltages V1, V2, V3 of the plurality of battery cells 2. Vcell2 and Vcell3 are set to Vbat = V1
Vcell1 = V1-V2
Vcell2 = V2-V3 Vcell3 = V3
As each seeking.

この制御・演算部２０は、基本的には通信処理部２３を介して前記制御・電源部３０の作動を制御して前記二次電池１の充電自体を制御する機能（満充電制御）、前述した充電制御スイッチ６の作動を制御して前記二次電池１の過充電を阻止する機能（過充電保護）、および前記放電制御スイッチ７の作動を制御して前記二次電池１の過放電を阻止する機能（過放電保護）を備える。   This control / calculation unit 20 basically controls the operation of the control / power supply unit 30 through the communication processing unit 23 to control the charging of the secondary battery 1 (full charge control), as described above. The function of preventing the overcharge of the secondary battery 1 by controlling the operation of the charge control switch 6 (overcharge protection) and the operation of the discharge control switch 7 are controlled to prevent the secondary battery 1 from being overdischarged. It has a function to prevent (over discharge protection).

上述した満充電制御機能は、ニッケル水素電池等においては、例えば二次電池１の充電時に該二次電池１の端子電圧Ｖbatが徐々に上昇し、満充電状態において上記端子電圧Ｖbatがピークに達した後、一定電圧（ΔＶ）だけ低下する現象を利用して満充電（１００％充電）状態を判定し（−ΔＶ方式）、二次電池１に対する充電を停止するものである。またリチウムイオン電池を充電するときのように電流値を所定値以下、電圧値を所定値以下にて充電する定電流・定電圧充電においては、定電流充電の後の定電圧充電時において、その充電電流値が所定値以下になると満充電と判定している。尚、電池温度Ｔの変化や充電電流Ｉの変化から満充電状態を検出する等、従来より種々提唱されている充電制御方式を適宜採用可能なことは言うまでもない。また本発明は二次電池１の満充電制御自体に直接関与するものではないので、満充電制御についてのこれ以上の説明は省略する。   In the above-described full charge control function, in a nickel metal hydride battery or the like, for example, when the secondary battery 1 is charged, the terminal voltage Vbat of the secondary battery 1 gradually increases, and the terminal voltage Vbat reaches a peak in the fully charged state. After that, the fully charged (100% charged) state is determined using the phenomenon that the voltage is decreased by a constant voltage (ΔV) (−ΔV method), and the charging of the secondary battery 1 is stopped. Moreover, in constant current / constant voltage charging that charges a current value below a predetermined value and a voltage value below a predetermined value as in charging a lithium ion battery, the constant voltage charging after constant current charging When the charging current value becomes a predetermined value or less, it is determined that the battery is fully charged. Needless to say, various charge control methods conventionally proposed, such as detecting a fully charged state from a change in the battery temperature T or a change in the charging current I, can be adopted as appropriate. In addition, since the present invention is not directly related to the full charge control of the secondary battery 1, further description of the full charge control is omitted.

一方、前述した過充電保護機能は、例えば二次電池１の端子電圧Ｖbatが予め設定した
二次電池１としての過充電保護電圧を超えたとき、或いは二次電池１を構成する複数段の電池セル２の個々の端子電圧Ｖcellが、各電池セル２に固有な過充電保護電圧を超えたとき、前述した充電制御スイッチ６を作動させてその充電路を強制的に遮断し、それ以上の充電（過充電）を阻止する役割を担う。尚、二次電池１の端子電圧Ｖbatは、充電制御に
おける満充電電圧により管理されているので、前記充電制御スイッチ６の作動による過充電防止は、専ら、個々の電池セル２の端子電圧Ｖcellが、その過充電保護電圧を超えたときに作動する。 On the other hand, the overcharge protection function described above is performed when, for example, the terminal voltage Vbat of the secondary battery 1 exceeds a preset overcharge protection voltage as the secondary battery 1 or a plurality of stages of batteries constituting the secondary battery 1. When the individual terminal voltage Vcell of the cell 2 exceeds the overcharge protection voltage specific to each battery cell 2, the charge control switch 6 described above is operated to forcibly cut off the charging path, and further charging is performed. Plays the role of preventing (overcharge). In addition, since the terminal voltage Vbat of the secondary battery 1 is managed by the full charge voltage in the charge control, the overcharge prevention by the operation of the charge control switch 6 is exclusively performed by the terminal voltage Vcell of each battery cell 2. Activated when the overcharge protection voltage is exceeded.

また過放電保護機能は、例えば二次電池１の端子電圧Ｖbatが予め設定した二次電池１
としての過放電保護電圧に近付いたとき、或いは複数段の電池セル２の個々の端子電圧Ｖcellが、各電池セル２に固有な過放電保護電圧に近付いたとき、或いは過放電保護電圧に至ったとき、前述した放電制御スイッチ７を作動させてその充電路を強制的に遮断して該二次電池１の深放電（過放電）を防止する役割を担う。 The overdischarge protection function is, for example, the secondary battery 1 in which the terminal voltage Vbat of the secondary battery 1 is set in advance.
When the voltage approaches the overdischarge protection voltage, or when the individual terminal voltages Vcell of the battery cells 2 of the plurality of stages approach the overdischarge protection voltage specific to each battery cell 2, or the overdischarge protection voltage is reached. At this time, the discharge control switch 7 described above is operated to forcibly cut off the charging path to prevent deep discharge (overdischarge) of the secondary battery 1.

このような機能の他にも前記制御・演算部２０は、例えば前述した電池温度Ｔから前記二次電池１の異常発熱が検出されたときや、前記充放電電流Ｉから二次電池１に対する異常（過大）な充放電電流が検出されたとき、充電制御スイッチ６および／または放電制御スイッチ７を作動させてその充放電路を遮断して、二次電池１のみならず負荷３２等を保護する機能等を備える。   In addition to such functions, the control / calculation unit 20 may detect, for example, abnormal heat generation of the secondary battery 1 from the battery temperature T described above, or abnormalities in the secondary battery 1 from the charge / discharge current I. When (excessive) charge / discharge current is detected, the charge control switch 6 and / or the discharge control switch 7 are operated to cut off the charge / discharge path, thereby protecting not only the secondary battery 1 but also the load 32 and the like. It has functions.

さて上述した過充電保護機能を備えた電池装置１０において本発明が特徴とするところは、前述した制御・演算部２０において二次電池１の過充電を検出して前述した充電制御スイッチ６を作動させたとき、二次電池１を構成する複数の電池セル２の端子電圧Ｖcellのバラツキに応じて上記二次電池１に対する充電制御電圧を低減し、これによって各電池セル２の充電電圧Ｖcellを過充電保護電圧Ｖlimt以下に抑えて二次電池１の継続使用を可能としたことにある。   The battery device 10 having the overcharge protection function described above is characterized in that the present invention is characterized in that the control / calculation unit 20 detects the overcharge of the secondary battery 1 and operates the charge control switch 6 described above. When this is done, the charging control voltage for the secondary battery 1 is reduced according to the variation in the terminal voltage Vcell of the plurality of battery cells 2 constituting the secondary battery 1, and thereby the charging voltage Vcell of each battery cell 2 is excessively exceeded. That is, the secondary battery 1 can be continuously used while being kept below the charge protection voltage Vlimt.

即ち、本発明に係る電池装置１０における制御・演算部２０は、前述した基本機能に加えて、複数の電池セル２間における電池特性のバラツキを判定するバラツキ検出手段２０ａと、複数の電池セル２間のバラツキが検出されたとき、電池セルの最大端子電圧に応じて前述した充電制御手段（制御・電源部３１）における充電制御電圧を低減する設定電圧変更手段２０ｂとを備えることを特徴としている。   That is, in addition to the basic functions described above, the control / calculation unit 20 in the battery device 10 according to the present invention includes a variation detection unit 20a that determines variation in battery characteristics between the plurality of battery cells 2, and a plurality of battery cells 2. And a setting voltage changing unit 20b for reducing the charging control voltage in the above-described charging control unit (control / power supply unit 31) according to the maximum terminal voltage of the battery cell when a variation between them is detected. .

具体的には上記バラツキ検出手段２０ａは、例えば前述した電池セル２の端子電圧Ｖcell１,Ｖcell２,Ｖcell３がその過充電保護電圧Ｖlimtを超えているか否かを判定している。
そして設定電圧変更手段２０ｂは、電池セル２の端子電圧Ｖcellが過充電保護電圧Ｖlimtを超えているとき、該電池セル２の端子電圧Ｖcellを上記過充電保護電圧Ｖlimt以下に抑えるべく、その後の二次電池１の充電制御電圧を低く設定するものとなっている。 Specifically, the variation detection means 20a determines whether, for example, the terminal voltages Vcell1, Vcell2, and Vcell3 of the battery cell 2 described above exceed the overcharge protection voltage Vlimt.
Then, when the terminal voltage Vcell of the battery cell 2 exceeds the overcharge protection voltage Vlimt, the set voltage changing means 20b performs the following two steps to keep the terminal voltage Vcell of the battery cell 2 below the overcharge protection voltage Vlimt. The charge control voltage of the secondary battery 1 is set low.

例えば３段直列に接続された３つの電池セル２の全てが正常な電池特性を有している場合、リチウムイオン電池を充電するときのように電流値を所定値以下、電圧値を所定値以下にて充電する定電流・定電圧充電において、二次電池１を規定の電圧Ｖ１まで充電したときにはこれらの電池セル２が略均等に充電されるので、各電池セル２の端子電圧Ｖcell１,Ｖcell２,Ｖcell３は図２(ａ)に示すように略等しくなる。しかしながら、例えば２段目の電池セル２の特性が劣化した場合、仮に二次電池１を規定の電圧Ｖ１まで充電したとしても、各電池セル２の端子電圧Ｖcell１,Ｖcell２,Ｖcell３にアンバランスが生じ、例えば図２(ｂ)に示すように２段目の電池セル２の端子電圧Ｖcell２だけが異常に高くなり、その分、１段目および３段目の電池セル２の端子電圧Ｖcell１,Ｖcell３が低く抑えら
れる。そして異常に高くなった２段目の電池セル２の端子電圧Ｖcell２を検出することで前述した過充電保護機能が作動し、それ以上の充電が阻止される（充電制御スイッチ６をオフとする）。このように過充電保護機能が作動する以前に、満充電が検出されたならばその充電自体が停止される。 For example, when all three battery cells 2 connected in series in three stages have normal battery characteristics, the current value is less than a predetermined value and the voltage value is less than a predetermined value as when charging a lithium ion battery. In the constant-current / constant-voltage charging, the battery cells 2 are charged substantially evenly when the secondary battery 1 is charged to the specified voltage V1, so that the terminal voltages Vcell1, Vcell2, Vcell3 is substantially equal as shown in FIG. However, for example, when the characteristics of the battery cell 2 in the second stage deteriorate, even if the secondary battery 1 is charged to the specified voltage V1, the terminal voltages Vcell1, Vcell2, and Vcell3 of each battery cell 2 are unbalanced. For example, as shown in FIG. 2 (b), only the terminal voltage Vcell2 of the second-stage battery cell 2 becomes abnormally high, and the terminal voltages Vcell1 and Vcell3 of the first-stage and third-stage battery cells 2 are accordingly increased. It can be kept low. Then, by detecting the terminal voltage Vcell2 of the battery cell 2 in the second stage that has become abnormally high, the above-described overcharge protection function is activated and further charging is prevented (the charge control switch 6 is turned off). . Thus, if full charge is detected before the overcharge protection function is activated, the charge itself is stopped.

しかしこの状態においては放電制御スイッチ７は作動していないので、二次電池１に充電した電力エネルギは、充電制御スイッチ６の寄生ダイオードおよび放電制御スイッチ７を介して取り出すことが可能である。従って電池装置１０そのものについては、負荷３２に対するバックアップ用電源としてそのまま継続使用可能である。しかしこの電源装置１０を再度充電して使用するには、既に２段目の電池セル２の性能結果に起因する過充電保護機能の作動の事実が確認されているので安全性が低下している。   However, since the discharge control switch 7 is not operating in this state, the power energy charged in the secondary battery 1 can be taken out via the parasitic diode of the charge control switch 6 and the discharge control switch 7. Therefore, the battery device 10 itself can be continuously used as a backup power source for the load 32. However, in order to charge and use the power supply device 10 again, the fact that the overcharge protection function is activated due to the performance result of the battery cell 2 in the second stage has already been confirmed, so the safety is lowered. .

そこでこの電池装置１０においては前述した設定電圧変更手段２０ｂを用いて、前記二次電池１を再充電する際の充電制御電圧（＝定電圧時の所定電圧値）を低減し、上述した性能が劣化した２段目の電池セル２の充電電圧Ｖcell２が過充電保護電圧Ｖlimt以下となるようにしている。具体的には、例えば過電圧保護機能が働いた際、又は充電を停止した際の各電池セル２の端子電圧Ｖcell１,Ｖcell２,Ｖcell３の比に基づいて、２段目の電池セル２の充電電圧Ｖcell２が過充電保護電圧Ｖlimt以下となるときの二次電池１に対する充電電圧Ｖbat’を求める。そして前記二次電池１を再充電する際の充電制御電圧として上記充電電圧Ｖbat’を設定し、二次電池１に対する充電電圧を図２(ｃ)に示すように低減する。すると二次電池１を構成する前記３段の電池セル２はその電池性能に応じて充電されるので、各電池セル２の端子電圧Ｖcell１,Ｖcell２,Ｖcell３は前述した電圧比に応じたものとなる。従って各電池セル２に対する充電容量が低減するものの、各電池セル２の端子電圧Ｖcell１,Ｖcell２,Ｖcell３のそれぞれが図２(ｃ)に示すように過充電保護電圧Ｖlimt以下に抑えられる。故に二次電池１の安全性を保証しながら、該二次電池１の再使用を可能とし得る。
上記の例では電圧バラツキの判断を過電圧保護機能が働いた際、又は充電を停止した際（例えば、満充電検出時）に行い、充電電圧への反映を再充電時としているが、充電電流が流れている状況で電圧バラツキ判断を行っても良いし、充電電圧への反映も充電中に行ってよい。
図４のフローにて、具体例での充電電圧Ｖbat（＝充電制御電圧＝定電圧時の所定電圧値）の変更について説明する。
ステップＳ４１において、保護を行いたい電圧として、過充電保護電圧Ｖlimtを、４．２Ｖとする。３つの電池セル２を充電するために、４．２Ｖ×３＝１２．６Ｖを充電電圧Ｖbatとして充電を行う。
ステップＳ４２において、端子電圧Ｖcell１,Ｖcell２,Ｖcell３において、いずれかの端子電圧が、過充電保護電圧Ｖlimtより大きい過電圧保護機能動作電圧Ｖprotect(＝４．３Ｖ)に至ったとき、過充電保護機能が作動して、充電を終了する。例として、Ｖcell１,Ｖcell２,Ｖcell３が、各々、４．２Ｖ、４．３Ｖ、４．１Ｖになり、充電を終了する。このような充電の終了は、このような過電圧保護機能動作電圧Ｖprotect(＝４．３Ｖ)に至ったときでなくても、満充電検出時（例えば、充電電流が所定値以下となったときや満充電検出電圧に到達したとき）に行ってもよい。
ステップＳ４３において、制御・演算部２０にて、充電電圧の変更を行う手順に入る。
ステップＳ４４において、過電圧保護機能動作電圧Ｖprotect(＝４．３Ｖ)に至ったＶcell２にて、各端子電圧を割り算すると、各端子電圧の比は、Vcell1: Vcell2: Vcell3 = 0.977:1:0.953となる。
ステップＳ４５において、比率を足し算した値に、保護を行いたい電圧である過充電保護電圧Ｖlimtをかけて、(0.977+1+0.953)*4.2V = 12.31Vの充電電圧を得る。この充電電圧で充電を行う。
ステップＳ４６において、通常、ステップＳ４５の後の充電時には、各端子電圧の比は、前回の比とほぼ同じで、充電が進むので、１２．３１Ｖにて充電するとき、満充電検出時（例えば、充電電流が所定値以下となったとき）、各端子電圧は、Vcell1,2,3 = 4.1V,4.2V,4.0Vとなり、電圧がもっとも高いＶcell２でも、過充電保護電圧Ｖlimt(４．２Ｖ)以下となる。そして、このようなフローを繰り返して、詳しい説明は省略するが負荷への放電と、充電とを繰り返すことになる。
また、図４のフローでは、各端子電圧、充電電圧に具体的な数値を用いて説明したが、図５のフローでは、このような値を、一般的数式を利用して、説明する。
ステップＳ５１において、保護を行いたい電圧として、過充電保護電圧Ｖlimtを、４．２Ｖとする。３つの電池セル２を充電するために、４．２Ｖ×３＝１２．６Ｖを充電電圧Ｖbatとして充電を行う。
ステップＳ５２において、充電終了時の端子電圧Ｖcell１,Ｖcell２,Ｖcell３を、確認する。このような充電の終了は、いずれかの端子電圧が過電圧保護機能動作電圧Ｖprotect(＝４．３Ｖ)に至ったとき、満充電検出したとき（例えば、充電電流が所定値以下となったときや満充電検出電圧に到達したとき）に行う。
ステップＳ５３において、制御・演算部２０にて、いずれかの端子電圧が、保護したい電圧Vlimitを超えているかを、確認する。保護したい電圧Vlimitを超えていないなら、ステップＳ５２に戻る。
保護したい電圧Vlimitを超えているなら、ステップＳ５４において、一番高い電圧を母数として、各端子電圧を割り算し、各端子電圧の比として、Vcell1: Vcell2: Vcell3 = r1:r2:r3を算出する。
ステップＳ５５において、比率を足し算した値に、保護を行いたい電圧である過充電保護電圧Ｖlimtをかけて、新充電電圧（=(r1+r2+r3)*Vlimit）を得る。そして、ステップＳ５６において、この新充電電圧で充電を行い、ステップＳ５２に戻る。
また、図５のフローでは、充電終了時の各端子電圧を確認して、充電電圧の変更を進めているが、図６のフローでは、充電を終了することなく、充電電流が流れている状況で電圧バラツキ判断を行っている。
ステップＳ６１において、保護を行いたい電圧として、過充電保護電圧Ｖlimtを、４．２Ｖとする。３つの電池セル２を充電するために、４．２Ｖ×３＝１２．６Ｖを充電電圧Ｖbatとして充電を行う。
ステップＳ６２において、充電を行いつつ、端子電圧Ｖcell１,Ｖcell２,Ｖcell３を、確認する。
ステップＳ６３において、制御・演算部２０にて、いずれかの端子電圧が、保護したい電圧Vlimitを超えているかを、確認する。保護したい電圧Vlimitを超えていないなら、ステップＳ６２に戻る。
保護したい電圧Vlimitを超えているなら、ステップＳ６４において、一番高い電圧を母数として、各端子電圧を割り算し、各端子電圧の比として、Vcell1: Vcell2: Vcell3 = r1:r2:r3を算出する。
ステップＳ６５において、比率を足し算した値に、保護を行いたい電圧である過充電保護電圧Ｖlimtをかけて、新充電電圧（=(r1+r2+r3)*Vlimit）を得る。そして、ステップＳ６６において、この新充電電圧で充電を行い、ステップＳ５２に戻る。 Therefore, in the battery device 10, the set voltage changing means 20b described above is used to reduce the charge control voltage (= predetermined voltage value at constant voltage) when the secondary battery 1 is recharged, and the performance described above is achieved. The charging voltage Vcell2 of the deteriorated second-stage battery cell 2 is set to be equal to or lower than the overcharge protection voltage Vlimt. Specifically, for example, the charging voltage Vcell2 of the battery cell 2 in the second stage is based on the ratio of the terminal voltages Vcell1, Vcell2, and Vcell3 of each battery cell 2 when the overvoltage protection function is activated or when the charging is stopped. The charging voltage Vbat ′ for the secondary battery 1 when the voltage becomes equal to or lower than the overcharge protection voltage Vlimt is obtained. Then, the charging voltage Vbat ′ is set as a charging control voltage when the secondary battery 1 is recharged, and the charging voltage for the secondary battery 1 is reduced as shown in FIG. Then, since the three-stage battery cells 2 constituting the secondary battery 1 are charged according to the battery performance, the terminal voltages Vcell1, Vcell2, and Vcell3 of each battery cell 2 correspond to the voltage ratio described above. . Accordingly, although the charging capacity for each battery cell 2 is reduced, the terminal voltages Vcell1, Vcell2, and Vcell3 of each battery cell 2 are suppressed to the overcharge protection voltage Vlimt or less as shown in FIG. Therefore, the secondary battery 1 can be reused while ensuring the safety of the secondary battery 1.
In the above example, the voltage variation is judged when the overvoltage protection function is activated or when charging is stopped (for example, when full charge is detected), and the reflection to the charging voltage is made when recharging. The voltage variation determination may be performed in a flowing state, and the reflection to the charging voltage may be performed during charging.
The change of the charging voltage Vbat (= charging control voltage = predetermined voltage value at constant voltage) in the specific example will be described with reference to the flow of FIG.
In step S41, the overcharge protection voltage Vlimt is set to 4.2V as a voltage to be protected. In order to charge the three battery cells 2, charging is performed with 4.2 V × 3 = 12.6 V as the charging voltage Vbat.
In step S42, when any one of the terminal voltages Vcell1, Vcell2, and Vcell3 reaches an overvoltage protection function operating voltage Vprotect (= 4.3V) that is larger than the overcharge protection voltage Vlimt, the overcharge protection function is activated. Then, charging ends. As an example, Vcell1, Vcell2, and Vcell3 become 4.2V, 4.3V, and 4.1V, respectively, and charging ends. The end of such charging is not when the overvoltage protection function operating voltage Vprotect (= 4.3 V) is reached, but when full charge is detected (for example, when the charging current becomes a predetermined value or less, Or when the full charge detection voltage is reached.
In step S43, the control / calculation unit 20 enters a procedure for changing the charging voltage.
In step S44, when each terminal voltage is divided by Vcell2 that has reached the overvoltage protection function operating voltage Vprotect (= 4.3V), the ratio of each terminal voltage is Vcell1: Vcell2: Vcell3 = 0.977: 1: 0.953. .
In step S45, the overcharge protection voltage Vlimt, which is a voltage to be protected, is multiplied by the value obtained by adding the ratios to obtain a charge voltage of (0.977 + 1 + 0.953) * 4.2V = 12.31V. Charging is performed at this charging voltage.
In step S46, normally, at the time of charging after step S45, the ratio of each terminal voltage is substantially the same as the previous ratio, and charging proceeds. Therefore, when charging at 12.31 V, when full charge is detected (for example, When the charging current falls below the specified value), the terminal voltages are Vcell1,2,3 = 4.1V, 4.2V, 4.0V, and overcharge protection voltage Vlimt (4.2V) even with the highest voltage Vcell2 It becomes as follows. Then, such a flow is repeated, and although detailed description is omitted, discharging to the load and charging are repeated.
Further, in the flow of FIG. 4, description has been made using specific numerical values for each terminal voltage and charging voltage, but in the flow of FIG. 5, such values will be described using general formulas.
In step S51, the overcharge protection voltage Vlimt is set to 4.2 V as a voltage to be protected. In order to charge the three battery cells 2, charging is performed with 4.2 V × 3 = 12.6 V as the charging voltage Vbat.
In step S52, the terminal voltages Vcell1, Vcell2, and Vcell3 at the end of charging are confirmed. Such charging is terminated when any of the terminal voltages reaches the overvoltage protection function operating voltage Vprotect (= 4.3 V), when full charge is detected (for example, when the charging current becomes a predetermined value or less, (When the full charge detection voltage is reached).
In step S53, the control / calculation unit 20 confirms whether any terminal voltage exceeds the voltage Vlimit to be protected. If the voltage Vlimit to be protected is not exceeded, the process returns to step S52.
If the voltage Vlimit to be protected is exceeded, in step S54, each terminal voltage is divided by using the highest voltage as a parameter, and Vcell1: Vcell2: Vcell3 = r1: r2: r3 is calculated as the ratio of each terminal voltage. To do.
In step S55, the overcharge protection voltage Vlimt, which is a voltage to be protected, is multiplied by the value obtained by adding the ratio to obtain a new charge voltage (= (r1 + r2 + r3) * Vlimit). In step S56, charging is performed with the new charging voltage, and the process returns to step S52.
Further, in the flow of FIG. 5, each terminal voltage at the end of charging is confirmed and the charging voltage is changed. However, in the flow of FIG. 6, the charging current flows without ending the charging. The voltage variation is judged by
In step S61, the overcharge protection voltage Vlimt is set to 4.2 V as a voltage to be protected. In order to charge the three battery cells 2, charging is performed with 4.2 V × 3 = 12.6 V as the charging voltage Vbat.
In step S62, the terminal voltages Vcell1, Vcell2, and Vcell3 are confirmed while charging.
In step S63, the control / arithmetic unit 20 confirms whether any terminal voltage exceeds the voltage Vlimit to be protected. If the voltage Vlimit to be protected is not exceeded, the process returns to step S62.
If the voltage Vlimit to be protected is exceeded, in step S64, each terminal voltage is divided using the highest voltage as a parameter, and the ratio of each terminal voltage is calculated as Vcell1: Vcell2: Vcell3 = r1: r2: r3. To do.
In step S65, the value obtained by adding the ratio is multiplied by the overcharge protection voltage Vlimt, which is a voltage to be protected, to obtain a new charge voltage (= (r1 + r2 + r3) * Vlimit). In step S66, charging is performed with the new charging voltage, and the process returns to step S52.

尚、二次電池１に対する充電制御電圧を低減するに際しては、例えば図３に示すように過充電保護機能の作動が繰り返し生じることを確認してから行うことが好ましい。
これにより、充電制御電圧の変更回数を減らすことができ、N回目の充電で下げた制御電圧値をN+1回目で戻す（上げる）といった頻繁に発生する充電電圧の変更をなくすことができる。
具体的には図３に示すようにその制御パラメータｎを初期設定した後（ステップＳ１）、前述した過充電保護機能が作動したか否かを判定する（ステップＳ２）。そして過充電保護機能が作動した場合には上記制御パラメータｎをインクリメントし（ステップＳ３）、制御パラメータｎが制御管理値Ｎに達したか否かを判定する（ステップＳ４）。そして制御パラメータｎが制御管理値Ｎに達したとき、つまり所定回数に亘って過充電保護機能が繰り返し作動したとき、電池セル２の性能が劣化したと判定して充電制御電圧を低減するようにすれば良い（ステップＳ５）。 In addition, when reducing the charge control voltage with respect to the secondary battery 1, it is preferable to carry out after confirming that the operation of the overcharge protection function repeatedly occurs, for example, as shown in FIG.
As a result, the number of changes in the charging control voltage can be reduced, and frequent changes in the charging voltage such as returning (increasing) the control voltage value lowered in the Nth charging in the N + 1th time can be eliminated.
Specifically, as shown in FIG. 3, after initializing the control parameter n (step S1), it is determined whether or not the above-described overcharge protection function is activated (step S2). When the overcharge protection function is activated, the control parameter n is incremented (step S3), and it is determined whether or not the control parameter n has reached the control management value N (step S4). When the control parameter n reaches the control management value N, that is, when the overcharge protection function is repeatedly activated for a predetermined number of times, it is determined that the performance of the battery cell 2 has deteriorated and the charge control voltage is reduced. (Step S5).

このようにな制御形態を採用すれば、例えば１つの電池セル２の性能が劣化しただけで、これを二次電池１としての性能の全てが劣化していると判定することがないので、電池性能が維持されている他の電池セル２が有する機能（電池性能）を十分に活用することができる。従って性能が劣化した電池セル２の過充電を防止してその安全性を確保しながら二次電池１が有する機能（性能）を十分に活用する上で好ましい。この際、充電制御電圧の低減、後述する過充電保護電圧Ｖlimtの低減によって二次電池１に充電し得る電気エネルギ量（充電量）も少なくなるので、例えば『電池性能が劣化しており、二次電池の交換時期が迫っている』旨の警告をメッセージ出力する（ステップＳ６）ことが望ましい。   If such a control form is adopted, for example, only the performance of one battery cell 2 is deteriorated, and it is not determined that all of the performance as the secondary battery 1 is deteriorated. The function (battery performance) of the other battery cells 2 whose performance is maintained can be fully utilized. Therefore, it is preferable in fully utilizing the function (performance) of the secondary battery 1 while preventing overcharging of the battery cell 2 whose performance has deteriorated and ensuring its safety. At this time, since the amount of electric energy (charge amount) that can be charged to the secondary battery 1 is reduced by reducing the charge control voltage and the overcharge protection voltage Vlimt described later, for example, “battery performance has deteriorated, It is desirable to output a warning message stating that the time for replacement of the next battery is approaching (step S6).

尚、図３に示したステップＳ５に代えて、前述したステップＳ４において制御パラメータｎが制御管理値Ｎに達したとき、予め設定した二次電池１に対する過充電保護電圧Ｖlimtを低減しても良い。このとき、過充電保護機能が動作した過充電状態の電池セルだけその過充電保護電圧Ｖlimtを低減しても良いし、全部の電池セルにおいて過充電保護電圧Ｖlimtを低減するようにしても良い。このような過充電保護電圧Ｖlimtを低減する機能は、制御・演算部２０が備えている。
また、更には、図３に示したステップＳ５に代えて、前述したステップＳ４において制御パラメータｎが制御管理値Ｎに達したとき、予め設定した二次電池１に対する過充電保護機能が作動する過充電保護機能動作電圧Ｖprotect(＝４．３Ｖ)を低減しても良い。このとき、過充電保護機能が動作した過充電状態の電池セルだけその過充電保護機能動作電圧Ｖprotectを低減しても良いし、全部の電池セルにおいて過充電保護機能動作電圧Ｖprotectを低減するようにしても良い。このような過充電保護機能動作電圧Ｖprotectを低減する機能は、制御・演算部２０が備えている。この場合、過充電保護機能動作電圧Ｖprotectは、過充電保護電圧Ｖlimtと表現することもできる。 Instead of step S5 shown in FIG. 3, when the control parameter n reaches the control management value N in step S4 described above, the overcharge protection voltage Vlimt for the secondary battery 1 set in advance may be reduced. . At this time, the overcharge protection voltage Vlimt may be reduced only in the overcharged battery cell in which the overcharge protection function is activated, or the overcharge protection voltage Vlimt may be reduced in all the battery cells. The control / arithmetic unit 20 has a function of reducing the overcharge protection voltage Vlimt.
Further, instead of step S5 shown in FIG. 3, when the control parameter n reaches the control management value N in step S4 described above, the overcharge protection function for the secondary battery 1 set in advance is activated. The charge protection function operating voltage Vprotect (= 4.3 V) may be reduced. At this time, the overcharge protection function operating voltage Vprotect may be reduced only in the overcharged battery cell in which the overcharge protection function is operated, or the overcharge protection function operation voltage Vprotect is reduced in all the battery cells. May be. Such a function of reducing the overcharge protection function operating voltage Vprotect is provided in the control / arithmetic unit 20. In this case, the overcharge protection function operating voltage Vprotect can also be expressed as an overcharge protection voltage Vlimt.

尚、本発明は上述した実施形態に限定されるものではない。例えば複数の電池セル２の端子電圧Ｖcellを個々にチェックすることに代えて複数の電池セル２の端子電圧を相互に比較し、これによって複数の電池セル２間のバラツキを判定するようにしても良い。そしてバラツキの度合いが大きいとき、二次電池１に対する充電制御電圧を低減するようにその充電を制御すれば良い。また充電制御電圧の低減の割合を一定化しておき、充電制御電圧の低減処理を数回実行したとき、これを二次電池１の寿命であると判定することも可能である。   The present invention is not limited to the embodiment described above. For example, instead of checking the terminal voltages Vcell of the plurality of battery cells 2 individually, the terminal voltages of the plurality of battery cells 2 are compared with each other, thereby determining the variation between the plurality of battery cells 2. good. When the degree of variation is large, the charging may be controlled so as to reduce the charging control voltage for the secondary battery 1. Moreover, it is also possible to determine that the life of the secondary battery 1 is reached when the charge control voltage reduction rate is made constant and the charge control voltage reduction process is executed several times.

またここでは二次電池１を主体として構成され、電子機器３０側に設けられた充電制御手段（制御電源部３１）に接続されて使用される電池パックを例に説明したが、二次電池１と共に、その充電制御手段（制御電源部３１）を内蔵した電池装置にも同様に適用することができることは勿論のことである。その他、本発明はその要旨を逸脱しない範囲で種々変形して実施することができる。   Further, here, the secondary battery 1 is mainly used, and the battery pack that is used by being connected to the charging control means (control power supply unit 31) provided on the electronic device 30 side has been described as an example. In addition, it goes without saying that the present invention can be similarly applied to a battery device incorporating the charging control means (control power supply unit 31). In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.

次に参考例１として、図７にブロック回路図を示す。参考例１においては、電池装置１０としての電池パック（＝バッテリーパック）１００及びこれを充電する充電器１３０を有している。この例においては、電池パック１００において、専用充電器１３０からの無負荷入力電圧を検出する制御回路１２０と、充電電流をＯＮ／ＯＦＦするスイッチング素子１０６を内蔵し、充電開始前に充電器１３０からの無負荷電圧値が正しい（＝専用充電器）である場合のみ、スイッチング素子１０６をＯＮし充電可能とするものである。
ここで、専用充電器１３０は、無負荷〜負荷時において出力電圧値がほとんど変化しないものであり、直流電源(CV/CC出力を備える)と、充電制御回路(高精度CV制御を備える)とを備えている。
そして、無負荷電圧検出／判定から、スイッチング素子１０６をＯＮするまでの間に所定のタイムラグを設けている。充電開始後もスイッチング素子１０６を周期的にＯＦＦし、同様の無負荷電圧の検出を継続して、無負荷電圧が所定値を超えた場合には、スイッチング素子をＯＦＦし充電を終了する。
この参考例１においては、専用充電器以外の充電器では充電されないため、安全性が向上する。

次に、参考例2として、充電時、放電時において、パック電池の温度上昇をおさえる構造について、説明する。パック電池内に、温度維持材料を配置することで、パック電池の温度上昇をおさえることができる。温度維持材料としては、三菱製紙(株)の商品「サーモメモリー」等を利用できる。
パック電池の温度上昇は、放電電流が大きいときに、また、充電の末期に、特に発生する。ここで、パック電池内の電池セルに、シート状の温度維持材料を巻く。温度維持材料は、電池セルの放電最大温度である８０℃近辺で温度維持できる材料とすることで、セルの温度上昇をおさえることができる。また、パック電池内の充電制御、放電制御を行うスイッチング素子のＦＥＴにおいて、ＦＥＴを封止するシリコン上に、温度維持材料を配置する。これにより、温度を数度〜5度程度低下させることができ、温度の定格がひとつ下のＦＥＴを利用することができる。

次に、参考例３として、プリチャージ異常検出について、以下に説明する。充放電制御機能を有するパック電池においては、電池電圧が低いとき、小電流にてプリチャージを行い、最小セル電圧が特定のセル電圧（3.0V）に到達したら、プリチャージから大電流の急速充電へ移行していた。一方、特定のセル電圧に、所定時間に到達しないものは、電池の異常として、充電を停止していた。ここで、パック電池内に、フ゜リチャーシ゛回路をもたず、充電電源を備えるＰＣ本体側にフ゜リチャーシ゛回路をもつものにおいて、電池電圧が低いにもかかわらず、通信で電池電圧不足（＝フ゜リチャーシ゛が必要）であることを伝達しているにもかかわらず、プリチャージを行わず、急速充電から開始するものがあった。
参考例３では、これを防止するために、パック電池側で、電池電圧不足でフ゜リチャーシ゛が必要な状態のときは、フ゜リチャーシ゛が一定時間ないことを検出して、異常検出する。つまり、プリチャージから急速充電へ移行する際の判定に、従来の最小セル電圧判定に加えて、プリチャージが開始されてから経過した時間が一定時間以上になることの判断をANDで追加する。閾値として使用するプリチャージの経過時間は、プリチャージ開始時の最小セル電圧で決まり、この時間が経過すれば3.0Vに十分到達するであろう時間とする。

次に、参考例４として、以下のように、電池チェック機能を備える充電器及びバッテリーシステムを利用することもできる。この例は、図１に示すパック電池（＝電池装置１０）と、これを充電制御する以下のような充電器が採用できる。参考例４においては、充電器において、パック電池からの通信（例えば、SMBus）で得られる電圧、電流及び温度データと、充電器で測定されたデータを比較チェックし、異常を検出した場合には、警告表示を行い、また、パック電池側に異常を知らせる機能を備える。このような情報により、充放電を禁止し、警告表示を、パック電池が行う。
電圧については、パック電池からSMBusを通じて出力されたセル電圧値のトータルと充電器で測定された電圧を比較して、差が大きい場合には、バッテリ異常として、警告表示を行う。また、電池パック側に異常を知らせ、充放電を禁止し、警告表示を行う。
電流については、パック電池からSMBusを通じて出力された電流値と充電器で測定された電流値を比較して、差が大きい場合には、バッテリ異常として、警告表示を行う。また、電池パック側に異常を知らせ、充放電を禁止し、警告表示を行う。
温度については、パック電池からSMBusを通じて出力されたパック電池の温度（パック電池内のマイコンに接続されたサーミスタに測定される温度）と充電器で測定された温度（バッテリ内のサーミスタを直接充電器のマイコンに接続して測定された温度）を比較して、差が大きい場合には、バッテリ異常として、警告表示を行う。また、電池パック側に異常を知らせ、充放電を禁止し、警告表示を行う。

次に、参考例５として、以下のようなバッテリーシステムを利用することができる。まず、問題として、今までは、パック電池が、異常な電圧、電流の充電器に接続された場合、パック電池内のイオン電池の保護回路が動作して、充電が停止する。例えば、異常に高い電圧の充電器で充電される場合に、過充電保護電圧まで充電された後に、充電が停止する。このような充電器を利用している場合、充電される度に、過充電保護電圧までの充電が繰り返されることとなる。この異常な充電が繰り返されることにより、電池の劣化、及び安全性が悪化する。
この問題を解決するため、参考例５においては、充電器とパック電池がお互いの情報を通信できる機能を備え、充電器のシリアル番号等の認証番号を、通信でパック電池にて認識できる。異常な電圧、電流で過去に充電された充電器の認証番号を、パック電池が記憶しておき、特定の認証番号の充電器により、所定回数以上、充電された場合に、パック電池側で充電が開始されないようにする機能を備える。これにより、異常な条件で、充電されない為、電池の劣化を防止し、安全性が確保できる。

次に、参考例６として、以下のような、過充電保護を行い、過充電によるダメージを軽減することができる。充電時、電池電圧が所定の過充電電圧を超えると、過充電を検出して、充電を停止し、過充電電圧より小さく設定された電圧（ヒステリシスを持たせた電圧）に下がったとき、充電停止を解除している。複数の電池セルを直列接続した組電池においては、長期にわたり使用しているとセル電圧にバラツキが起こり、特定のセルの過充電を検出し、過充電保護動作と、解除が繰り返し頻繁に行われるようになる。
この問題を解消するために、参考例６においては、過充電に至る回数を、所定回数検出すると、上記ヒステリシスを持たせた電圧に低下したことに加えて、充電停止の解除を、一定時間、延期させるようにする。これにより、過充電保護動作の回数を減らすことができ、電池に対するダメージが低減し、安全性が確保できる。

次に、参考例７として、以下のように、過放電保護を行い、イオン電池を適切に使用することができる。
過放電保護を設けたリチウムイオン電池のパック電池においては、過放電電圧を、単一の電圧値としていた。大電流放電によって、まだ残量が残っていても、電流が流れている間、電圧が低下するが、放電電流が小さくなると電圧が高い値に戻る。こうした過渡的な電圧低下でも、セルはダメージを受けるが、その程度は、本当に残量が低下して電圧が低下した場合に比べて、著しく軽い。
そこで、参考例７においては、流れる電流を閾値にして、複数の過放電保護電圧を設定することで、大電流放電による一時的な電圧低下では、低い電圧にて過放電保護を行い、放電電流がゼロか低い値の場合は、高い電圧で過放電保護をかける。これにより、セルへのダメージを最小限にとどめつつ、セルの放電能力を最大限に引き出すことができる。
更には、セルの温度を考慮した過放電保護電圧とすることもできる。即ち、低温時には、放電電流による電圧低下が大きく現れるため、高温時に比べ、より過放電保護電圧を下げることで、セルの能力をより引き出すことが可能になる。また、２段階でなく、温度と放電電流を因子にして、多段階、あるいは、連続的に、過放電電圧を変化させることもできる。具体的には、例えば、放電電流０．２ＣＡ未満が１０秒連続したときは、過放電保護を、２．５Ｖ／cellで作動させる。また、放電電流０．２ＣＡ以上を検出したとき、過放電保護を、１．５Ｖ／cellで作動させる。 Next, as reference example 1, a block circuit diagram is shown in FIG. The reference example 1 includes a battery pack (= battery pack) 100 as the battery device 10 and a charger 130 that charges the battery pack. In this example, the battery pack 100 includes a control circuit 120 that detects a no-load input voltage from the dedicated charger 130 and a switching element 106 that turns on / off the charging current. Only when the no-load voltage value is correct (= dedicated charger), the switching element 106 is turned on to enable charging.
Here, the dedicated charger 130 has an output voltage value that hardly changes during no load to a load, and includes a DC power supply (with CV / CC output), a charge control circuit (with high precision CV control), and It has.
A predetermined time lag is provided between the detection / determination of the no-load voltage and the time when the switching element 106 is turned on. Even after the start of charging, the switching element 106 is periodically turned off, and the detection of the same no-load voltage is continued. When the no-load voltage exceeds a predetermined value, the switching element is turned off and the charging is finished.
In this reference example 1, since it is not charged with chargers other than a dedicated charger, safety improves.

Next, as Reference Example 2, a structure that suppresses the temperature rise of the battery pack during charging and discharging will be described. By arranging the temperature maintaining material in the battery pack, the temperature rise of the battery pack can be suppressed. As a temperature maintaining material, a product “Thermo Memory” manufactured by Mitsubishi Paper Industries Co., Ltd. can be used.
The rise in temperature of the battery pack occurs particularly when the discharge current is large and at the end of charging. Here, a sheet-like temperature maintaining material is wound around the battery cells in the battery pack. The temperature maintaining material is a material that can maintain the temperature in the vicinity of 80 ° C., which is the maximum discharge temperature of the battery cell, so that the temperature rise of the cell can be suppressed. Moreover, in the FET of the switching element that performs charge control and discharge control in the battery pack, a temperature maintaining material is disposed on the silicon that seals the FET. As a result, the temperature can be lowered by several degrees to 5 degrees, and an FET having a lower temperature rating can be used.

Next, precharge abnormality detection will be described below as Reference Example 3. In battery packs with charge / discharge control functions, precharge is performed with a small current when the battery voltage is low, and when the minimum cell voltage reaches a specific cell voltage (3.0V), rapid charging from precharge to large current is performed. Had moved to. On the other hand, if the specific cell voltage does not reach the predetermined time, charging is stopped as a battery abnormality. Here, the battery pack does not have a precharge circuit and has a charge circuit on the side of the PC equipped with a charging power supply. Even though the battery voltage is low, the battery voltage is low due to communication (= precharge). However, there are some that start with quick charging without precharging.
In Reference Example 3, in order to prevent this, when the battery needs to be recharged due to insufficient battery voltage, it is detected that there is no precharge for a certain period of time, and an abnormality is detected. In other words, in addition to the conventional minimum cell voltage determination, a determination that the time elapsed after the start of the precharge is a certain time or more is added to the determination at the time of shifting from precharge to quick charge. The elapsed time of the precharge used as the threshold is determined by the minimum cell voltage at the start of the precharge. If this time elapses, it will be a time that will sufficiently reach 3.0V.

Next, as Reference Example 4, a charger and a battery system having a battery check function can be used as follows. In this example, the battery pack (= battery device 10) shown in FIG. 1 and the following charger that controls charging of the battery can be employed. In Reference Example 4, in the charger, the voltage, current, and temperature data obtained by communication from the battery pack (for example, SMBus) is compared with the data measured by the charger, and if an abnormality is detected, A function is provided for displaying a warning and notifying the battery pack of the abnormality. Based on such information, charging / discharging is prohibited, and the battery pack displays a warning.
Regarding the voltage, the total cell voltage value output from the battery pack through the SMBus is compared with the voltage measured by the charger, and if the difference is large, a warning is displayed as a battery abnormality. In addition, the battery pack is notified of the abnormality, charging / discharging is prohibited, and a warning is displayed.
Regarding the current, the current value output from the battery pack through the SMBus is compared with the current value measured by the charger, and if the difference is large, a warning is displayed as a battery abnormality. In addition, the battery pack is notified of the abnormality, charging / discharging is prohibited, and a warning is displayed.
Regarding the temperature, the temperature of the battery pack output from the battery pack via SMBus (the temperature measured by the thermistor connected to the microcomputer in the battery pack) and the temperature measured by the charger (the thermistor in the battery charger directly) If the difference is large, a warning is displayed as a battery abnormality. In addition, the battery pack is notified of the abnormality, charging / discharging is prohibited, and a warning is displayed.

Next, as Reference Example 5, the following battery system can be used. First, as a problem, until now, when the battery pack is connected to a charger having an abnormal voltage or current, the protection circuit for the ion battery in the battery pack operates to stop charging. For example, when charging with an abnormally high voltage charger, charging stops after charging to the overcharge protection voltage. When such a charger is used, charging up to the overcharge protection voltage is repeated each time the battery is charged. By repeating this abnormal charging, the battery is deteriorated and the safety is deteriorated.
In order to solve this problem, in Reference Example 5, the charger and the battery pack have a function of communicating information with each other, and the authentication number such as the serial number of the charger can be recognized by the battery pack by communication. The pack battery memorizes the authentication number of the charger that was charged in the past with an abnormal voltage or current. Has a function to prevent the start. As a result, since the battery is not charged under abnormal conditions, the battery can be prevented from deteriorating and safety can be ensured.

Next, as Reference Example 6, the following overcharge protection can be performed to reduce damage due to overcharge. When charging, if the battery voltage exceeds the specified overcharge voltage, overcharge is detected, charging is stopped, and the battery is charged when the voltage drops below the overcharge voltage (voltage with hysteresis). The stop is released. In an assembled battery in which a plurality of battery cells are connected in series, the cell voltage varies when used for a long period of time, overcharge of a specific cell is detected, and overcharge protection operation and release are repeated frequently. It becomes like this.
In order to solve this problem, in Reference Example 6, when the number of times of overcharge is detected a predetermined number of times, in addition to the voltage being reduced to the above-mentioned hysteresis, the release of the charge stop is canceled for a certain period of time. Try to postpone it. Thereby, the frequency | count of an overcharge protection operation can be reduced, the damage with respect to a battery can be reduced, and safety | security can be ensured.

Next, as Reference Example 7, overdischarge protection is performed as follows, and an ion battery can be appropriately used.
In a battery pack of a lithium ion battery provided with overdischarge protection, the overdischarge voltage is set to a single voltage value. Even if the remaining amount remains due to the large current discharge, the voltage decreases while the current flows, but when the discharge current decreases, the voltage returns to a high value. Even with such a transient voltage drop, the cell is damaged, but the extent is significantly lighter than when the battery level is really lowered and the voltage drops.
Therefore, in Reference Example 7, by setting a plurality of overdischarge protection voltages using the flowing current as a threshold value, overdischarge protection is performed at a low voltage in the case of a temporary voltage drop due to large current discharge. If is zero or low, apply overdischarge protection at high voltage. This makes it possible to maximize the discharge capability of the cell while minimizing damage to the cell.
Furthermore, the overdischarge protection voltage can be set in consideration of the cell temperature. That is, since a voltage drop due to the discharge current appears greatly at low temperatures, the cell capability can be further extracted by lowering the overdischarge protection voltage more than at high temperatures. In addition, the overdischarge voltage can be changed in multiple stages or continuously using factors of temperature and discharge current instead of two stages. Specifically, for example, when the discharge current of less than 0.2 CA continues for 10 seconds, the overdischarge protection is activated at 2.5 V / cell. Further, when a discharge current of 0.2 CA or more is detected, the overdischarge protection is activated at 1.5 V / cell.

本発明の一実施形態に係る電池装置の要部概略構成図。The principal part schematic block diagram of the battery apparatus which concerns on one Embodiment of this invention. 本発明に係る電池装置での二次電池に対する充電電圧制御の概念を模式的に示す図。The figure which shows typically the concept of the charge voltage control with respect to the secondary battery in the battery apparatus which concerns on this invention. 本発明の一実施形態に係る電池装置における充電制御電圧の低減処理実行手順の例を示す図。The figure which shows the example of the reduction process execution procedure of the charge control voltage in the battery apparatus which concerns on one Embodiment of this invention. 本発明の一実施形態に係る電池装置における充電制御電圧の低減処理実行手順の例（例2）を示す図。The figure which shows the example (example 2) of the reduction process execution procedure of the charge control voltage in the battery apparatus which concerns on one Embodiment of this invention. 本発明の一実施形態に係る電池装置における充電制御電圧の低減処理実行手順の例（例３）を示す図。The figure which shows the example (example 3) of the reduction process execution procedure of the charge control voltage in the battery apparatus which concerns on one Embodiment of this invention. 本発明の一実施形態に係る電池装置における充電制御電圧の低減処理実行手順の例（例４）を示す図。The figure which shows the example (example 4) of the reduction process execution procedure of the charge control voltage in the battery apparatus which concerns on one Embodiment of this invention. 参考例1を示すブロック回路図である。6 is a block circuit diagram showing Reference Example 1. FIG.

符号の説明Explanation of symbols

１ 二次電池
２ 電池セル
２０ 制御・演算部
２０ａ バラツキ検出手段
２０ｂ 設定電圧変更手段 ３１ 制御・電源部
３２ 負荷 DESCRIPTION OF SYMBOLS 1 Secondary battery 2 Battery cell 20 Control / arithmetic unit 20a Variation detection means 20b Setting voltage change means 31 Control / power supply part 32 Load

Claims (5)

複数の電池セルを直列に接続した二次電池と、
この二次電池の端子電圧および前記各電池セルの端子電圧をそれぞれ検出する電圧検出手段と、
前記二次電池の端子電圧に応じて該二次電池に対する充電を制御する充電制御手段と、
前記各電池セルの端子電圧から前記複数の電池セル間における電池特性のバラツキを判定するバラツキ検出手段と、
前記複数の電池セル間のバラツキが検出されたとき、前記二次電池に対する過充電保護電圧を低減する制御・演算部と
を具備したことを特徴とする電池装置。 A secondary battery in which a plurality of battery cells are connected in series;
Voltage detecting means for detecting the terminal voltage of the secondary battery and the terminal voltage of each of the battery cells, and
Charging control means for controlling charging of the secondary battery according to the terminal voltage of the secondary battery;
Variation detection means for determining variation in battery characteristics between the plurality of battery cells from the terminal voltage of each of the battery cells;
A battery device comprising: a control / arithmetic unit that reduces an overcharge protection voltage with respect to the secondary battery when variation between the plurality of battery cells is detected. 複数の電池セルを直列に接続した二次電池と、
この二次電池の端子電圧および前記各電池セルの端子電圧をそれぞれ検出する電圧検出手段と、
前記二次電池の端子電圧に応じて該二次電池に対する充電を制御する充電制御手段と、
前記各電池セルの端子電圧から前記複数の電池セル間における電池特性のバラツキを判定するバラツキ検出手段と、
前記複数の電池セル間のバラツキが検出されたとき、電池セルの最大端子電圧に応じて前記充電制御手段における充電制御電圧を低減する設定電圧変更手段と
を具備したことを特徴とする電池装置。 A secondary battery in which a plurality of battery cells are connected in series;
Voltage detecting means for detecting the terminal voltage of the secondary battery and the terminal voltage of each of the battery cells, and
Charging control means for controlling charging of the secondary battery according to the terminal voltage of the secondary battery;
Variation detection means for determining variation in battery characteristics between the plurality of battery cells from the terminal voltage of each of the battery cells;
A battery device comprising: a set voltage changing unit configured to reduce a charge control voltage in the charge control unit according to a maximum terminal voltage of the battery cell when a variation between the plurality of battery cells is detected. 前記バラツキ検出回路は、前記各電池セルの端子電圧を相互に比較して複数の電池セル間のバラツキを判定するものである請求項１または２に記載の電池装置。   The battery device according to claim 1, wherein the variation detection circuit determines a variation between a plurality of battery cells by comparing terminal voltages of the battery cells with each other. 前記バラツキ検出回路は、前記各電池セルの端子電圧が、その過充電保護電圧を超えるか否かをそれぞれ判定して複数の電池セル間のバラツキを判定するものである請求項１または２に記載の電池装置。   The said variation detection circuit determines whether each battery cell terminal voltage exceeds the overcharge protection voltage, respectively, and determines the variation between several battery cells. Battery device. 前記設定電圧変更手段は、電池セルの最大端子電圧がその過充電保護電圧よりも低くなるように前記二次電池に対する充電制御電圧を変更するものである請求項２に記載の電池装置。   The battery device according to claim 2, wherein the set voltage changing means changes a charge control voltage for the secondary battery so that a maximum terminal voltage of the battery cell is lower than an overcharge protection voltage.
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