【発明の詳細な説明】[Detailed description of the invention]
本発明は充放電サイクルの使用される鉛蓄電池
の充電方法に関するものである。
バツテリーフオーク、電気自動車あるいはゴル
フカートなどに用いられる鉛蓄電池の充電方法に
は、周知のように準定電流と定電流・定電圧が一
般的である。後者は３〜10時間率の定電流、2.30
〜2.50V／セルの定電圧が常用されている。充電
電力を節約する上では定電流・定電圧充電が好し
いが、この方式では過充電が少なく、ガツシング
がほとんどなく、電解液は撹拌されない。充電中
には正極板および負極板ともに硫酸を排出し、こ
れは重いので電解液は下部が高濃度に、即ち高比
重になる。液比重と正極板および負極板の平衡電
位との関係は第１図に示したように液比重が高い
と正極板は貴に、負極板は卑になり、したがつて
開路電圧は高くなる。充電時の電流は充電器から
の印加電圧と開路電圧との差に応じて流れる。定
電流・定電圧充電では後半の定電圧充電時に電流
はおもに低比重雰囲気にある極板の上部に流れ、
極板下部に充分に充電されない。充電末期に高い
電圧を付加してガス発生により電解液上下の比重
差を解消する提案もあるが、これでは極板下部の
完全な充電はできない。
本発明は深い放電後の充電を過充電量が少な
く、しかも極板全体を充分に充電することによ
り、省電力と電池性能の充分な発揮とを実現する
ことを目的としている。
本発明の要旨は充電により端子電圧が所定の値
（所定の値とは、セル当り2.30〜2.50Vである。）
に達したときに、電解液の上部および下部の比重
を検出し、その差異が0.10以上の場合に高電圧を
印加して、公称放電容量の２〜５％の電気量を短
時間で充電した後、定電圧充電に移行する鉛蓄電
池の充電方法にある。
本発明になる充電において、前半は定電流充電
であり、電流値は通常の３〜10時間率が好まし
い。電池の端子電圧は充電の進行につれて徐々に
上昇するが、2.30〜2.50V／セルに達するまでは
充電電流は活物質の充電に消費されて、水の電気
分解によるガス発生はほとんど生じない。完全放
電後の電池を通常の電流、すなわち３〜10時間率
電流で充電すると、約80％充電されたときに端子
電圧は2.30〜2.50V／セルとなるが、この時に電
解液上部と下部の比重差は0.20程度に達し、下部
が高比重となる。浅い放電、例えば公称容量の20
％を放電した後充電した場合には、電解液の上部
と下部との比重差は0.10未満であつて比較的均一
である。
電解液の上部および下部の比重は、光の屈折
率、鉛、二酸化鉛、カドミウムなどの単極電位、
水蒸気圧、適当な物体の浮力などで検出できるの
で、その差をとれば上部と下部との比重差が得ら
れる。この比重差が0.10以上、特に0.20以上ある
と、通常の定電流・定電圧充電では、低比重の極
板上部に電流が集中して、下部は長時間充電を継
続しても未充電の活物質が存在してしまう。
本発明になる充電では定電圧充電に移行する前
に高電圧を印加して、大電流で公称容量の２〜５
％の電気量を短時間で充電し、正および負極板か
らガスを発生させて、電解液の上下の比重差を解
消する。高電圧を印加して大電流を流す方法とし
ては、2.50〜2.80V／セルの高い定電圧充電を行
うものと、定電流充電を所定時間だけ延長、継続
してその時は端子電圧が上昇するにまかせておく
ものとがある。この時の充電電気量は電池の公称
容量の２〜５％の電気量が好ましい。少ないと電
解液の撹拌が不充分、多いと電力が無駄となるだ
けでなく、過充電で正極格子が腐食し、劣化が早
くなる。
このガス発生を伴う短時間の充電後では、2.30
〜2.50V／セルの低い電圧で１〜10hの長時間充
電を行う。この時には正、負極活物質の少量の未
充電部分が徐々にかつ完全に充電され、しかも電
力の損失は少ない。
つぎに5hR容量215Ahのクラツド式鉛蓄電池に
ついて完全放電後に第２図に示す外部特性の二種
類の充電器で充電した。ａは従来からの定電流・
定電圧充電器であり、端子電圧が2.40V／セル以
下では60Aの定電流充電が行われ、端子電圧が
2.40V／セルに達するとその電圧が維持されて電
流は垂下し０〜60Aの範囲にあることを示してい
る。ｂは本発明になる充電方法に用いる充電器の
一例であり、60Aの定電流充電を行つて端子電圧
が2.40V／セルに達してもなお60V定電流充電が
持続され、端子電圧は2.80V／セルまでは上昇で
きる。所定の短時間だけ2.40〜2.80V／セルの高
電圧で充電された後は2.40V／セルの定電流充電
に移行し、電流は０〜60Aの範囲で垂下する。
この時の電池の充電特性は第３図の通りであつ
た。従来の定電流・定電圧充電ａでは、端子電圧
が2.4V／セルまでは電圧は徐々に上昇し電流は
60A一定、それ以降は電圧は2.40V／セル一定で
電流は60Aから急激に垂下している。電圧が
2.40V／セルの時に電解液の上下の比重差は0.185
であつた。本発明になる充電方法ｂでは、端子電
圧が2.40V／セルに達してもさらに10分間定電流
充電が継続しており、この時の端子電圧は約
2.60V／セルまで上昇し、その後で2.40V／セル
の定電圧充電に移行し、充電電流は従来の方法ａ
の場合よりもさらに急激に垂下し、全体の充電電
気量はｂの方がａよりもむしろ少なかつた。端子
電圧が2.40〜2.60V／セルの間にはかなりのガス
が発生し、電解液の上下の比重左はこの10分間の
高電圧の充電によつて0.185から0.040に減少して
いた。この充電後の電解液上部の比重と5hR放電
量とを比較して第１表に示す。また別の電池で同
じ条件での充電したのち正極活物質中の硫酸鉛量
を第１表にあわせて示す。
The present invention relates to a method of charging a lead-acid battery used in a charge-discharge cycle. As is well known, quasi-constant current and constant current/constant voltage are commonly used to charge lead-acid batteries used in battery forks, electric vehicles, golf carts, and the like. The latter is a constant current with a rate of 3 to 10 hours, 2.30
A constant voltage of ~2.50V/cell is commonly used. Constant-current/constant-voltage charging is preferable to save charging power, but with this method there is little overcharging, almost no gassing, and the electrolyte is not stirred. During charging, sulfuric acid is discharged from both the positive electrode plate and the negative electrode plate, and since this is heavy, the electrolyte has a high concentration in the lower part, that is, a high specific gravity. The relationship between the specific gravity of the liquid and the equilibrium potential of the positive electrode plate and the negative electrode plate is as shown in FIG. 1. When the specific gravity of the liquid is high, the positive electrode plate becomes noble and the negative electrode plate becomes noble, so that the open circuit voltage becomes high. Current during charging flows according to the difference between the applied voltage from the charger and the open circuit voltage. In constant current/constant voltage charging, during the second half of constant voltage charging, the current mainly flows to the top of the electrode plate, which is in a low specific gravity atmosphere.
The lower part of the electrode plate is not sufficiently charged. There is also a proposal to apply a high voltage at the end of charging to eliminate the difference in specific gravity between the top and bottom of the electrolyte by generating gas, but this method does not allow complete charging of the lower part of the electrode plate. An object of the present invention is to reduce the amount of overcharging during charging after deep discharging, and to sufficiently charge the entire electrode plate, thereby realizing power saving and sufficient performance of the battery. The gist of the present invention is that the terminal voltage is set to a predetermined value by charging (the predetermined value is 2.30 to 2.50V per cell).
When the specific gravity of the upper and lower parts of the electrolyte was reached, the specific gravity of the upper and lower parts of the electrolyte was detected, and if the difference between them was 0.10 or more, a high voltage was applied to charge the battery with an amount of electricity of 2 to 5% of the nominal discharge capacity in a short time. The next step is how to charge a lead-acid battery, which shifts to constant voltage charging. In the charging according to the present invention, the first half is constant current charging, and the current value is preferably a normal 3 to 10 hour rate. The terminal voltage of the battery gradually increases as charging progresses, but until it reaches 2.30 to 2.50 V/cell, the charging current is consumed to charge the active material, and gas generation due to water electrolysis hardly occurs. When a fully discharged battery is charged with a normal current, that is, a 3 to 10 hour rate current, the terminal voltage will be 2.30 to 2.50 V/cell when it is approximately 80% charged, but at this time, the electrolyte at the top and bottom will be charged. The difference in specific gravity reaches about 0.20, with the lower part having higher specific gravity. Shallow discharge, e.g. 20 of nominal capacity
When charging after discharging %, the difference in specific gravity between the upper and lower parts of the electrolyte is less than 0.10 and relatively uniform. The specific gravity of the upper and lower parts of the electrolyte is determined by the refractive index of light, the unipolar potential of lead, lead dioxide, cadmium, etc.
It can be detected by water vapor pressure, buoyancy of a suitable object, etc., and by taking the difference, you can get the difference in specific gravity between the upper and lower parts. If this specific gravity difference is 0.10 or more, especially 0.20 or more, in normal constant current/constant voltage charging, the current will concentrate on the upper part of the electrode plate with low specific gravity, and the lower part will remain uncharged even if charging continues for a long time. A substance exists. In the charging according to the present invention, a high voltage is applied before transitioning to constant voltage charging, and a large current is used to charge 2 to 5 % of the nominal capacity.
% of electricity in a short time, gas is generated from the positive and negative electrode plates, and the difference in specific gravity between the top and bottom of the electrolyte is eliminated. There are two ways to apply a high voltage and flow a large current: one is to charge at a high constant voltage of 2.50 to 2.80V/cell, and the other is to extend and continue constant current charging for a predetermined time until the terminal voltage increases. There are things you can leave to yourself. The amount of electricity charged at this time is preferably 2 to 5% of the nominal capacity of the battery. If it is too little, the electrolyte will not be stirred sufficiently, and if it is too much, not only will electricity be wasted, but the positive electrode grid will corrode due to overcharging, leading to faster deterioration. After a short charging period with this gas generation, 2.30
Charge for a long time of 1 to 10 hours at a low voltage of ~2.50V/cell. At this time, the small amount of uncharged portions of the positive and negative electrode active materials are gradually and completely charged, and there is little loss of power. Next, a closed-type lead-acid battery with a 5hR capacity of 215Ah was fully discharged and then charged using two types of chargers with external characteristics shown in Figure 2. a is the conventional constant current
It is a constant voltage charger, and when the terminal voltage is 2.40V/cell or less, constant current charging of 60A is performed, and the terminal voltage is lower than 2.40V/cell.
When it reaches 2.40V/cell, that voltage is maintained and the current drops, indicating that it is in the range of 0 to 60A. b is an example of a charger used in the charging method of the present invention, and even when the terminal voltage reaches 2.40V/cell after 60A constant current charging, the 60V constant current charging is continued and the terminal voltage is 2.80V. You can climb up to /cell. After being charged at a high voltage of 2.40 to 2.80 V/cell for a predetermined short time, the charge shifts to constant current charging of 2.40 V/cell, and the current drops in the range of 0 to 60 A. The charging characteristics of the battery at this time were as shown in FIG. In conventional constant current/constant voltage charging a, the voltage gradually increases and the current decreases until the terminal voltage reaches 2.4V/cell.
The voltage is constant at 60A, and after that the voltage is constant at 2.40V/cell, and the current drops rapidly from 60A. voltage is
At 2.40V/cell, the difference in specific gravity between the top and bottom of the electrolyte is 0.185
It was hot. In charging method b according to the present invention, even if the terminal voltage reaches 2.40V/cell, constant current charging continues for another 10 minutes, and the terminal voltage at this time is approximately
The charging current increases to 2.60V/cell, then shifts to constant voltage charging of 2.40V/cell, and the charging current is the same as the conventional method a.
It dropped even more rapidly than in the case of case b, and the total amount of charged electricity was actually smaller in case b than in case a. A considerable amount of gas was generated when the terminal voltage was between 2.40 and 2.60 V/cell, and the specific gravity of the upper and lower parts of the electrolyte decreased from 0.185 to 0.040 due to the 10 minutes of high voltage charging. Table 1 shows a comparison between the specific gravity of the upper part of the electrolyte after charging and the 5hR discharge amount. Table 1 also shows the amount of lead sulfate in the positive electrode active material after charging another battery under the same conditions.
【表】
上記第１表より明らかなように本発明充電方法
による充電では、電解液比重は上部の値も所定の
値1.280に近く、上下の濃度差はほとんどない。
さらに容量は完全に回復しており、極板もよく
充電されている。
本発明は以上に詳述したように、充電電力の損
失や過充電による正極板の劣化がなく、しかも活
物質を完全に充電して電池性能を充分に発揮させ
る充電方法を提供するものである。[Table] As is clear from Table 1 above, when charging according to the charging method of the present invention, the upper value of the electrolyte specific gravity is also close to the predetermined value of 1.280, and there is almost no difference in concentration between the upper and lower portions. Furthermore, the capacity has been fully restored and the plates are well charged. As detailed above, the present invention provides a charging method that does not cause loss of charging power or deterioration of the positive electrode plate due to overcharging, and moreover, completely charges the active material and fully demonstrates battery performance. .
【図面の簡単な説明】[Brief explanation of drawings]
第１図は液比重と正・負極板の電位との関係を
示す説明図、第２図は充電器の外部特性図、第３
図はその充電器で充電したときの電池特性図で、
それぞれａは従来の充電法、ｂは本発明になる充
電方法を示している。
Figure 1 is an explanatory diagram showing the relationship between liquid specific gravity and the potential of the positive and negative electrode plates, Figure 2 is an external characteristic diagram of the charger, and Figure 3
The figure shows the battery characteristics when charging with that charger.
In each case, a shows a conventional charging method, and b shows a charging method according to the present invention.