充電時,鉛酸蓄電池充電器的參數指標
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電動車鉛酸蓄電池組充電時，有幾個關鍵參數：最高充電電壓、浮充電壓、浮充轉換電流、最大充電電流。它們應該是多少？如何制定？其中最主要的是最高充電電壓，多少為好？與析氣量、充入電容量和環境溫度又是什么關系？對此眾說不一，各電池生產廠家的要求也不一樣。最高充電電壓值相對誤差范圍是多少？我們不能脫離實際的工作對象，盲目制定出超常規的精度要求。我們接到某電動車售后服務部通知：充電器比規定(ding)電(dian)(dian)壓高(gao)0.1V，電(dian)(dian)池因此(ci)熱失控而充脹了(le)；也接(jie)到通知說：電(dian)(dian)壓比規定(ding)定(ding)低0.1V，電(dian)(dian)池欠充，提前報(bao)廢。一個(ge)千分之(zhi)幾的(de)誤差造成如(ru)此(ci)嚴重后果(guo)，真是失之(zhi)毫厘，謬之(zhi)千里(li)之(zhi)外，鉛(qian)酸蓄電(dian)(dian)池果(guo)真有這么神秘(mi)嗎？為了(le)解開困擾電(dian)(dian)動(dong)車(che)充電(dian)(dian)中(zhong)的(de)這個(ge)謎團，做如(ru)下實驗。
用(yong)一(yi)個(ge)(ge)水槽盛滿水，電(dian)(dian)(dian)池放在(zai)水中，在(zai)電(dian)(dian)(dian)池上(shang)方有(you)一(yi)個(ge)(ge)收集氣(qi)(qi)體(ti)用(yong)的(de)倒扣的(de)漏(lou)斗(dou)，漏(lou)斗(dou)頂端裝有(you)可以(yi)計量(liang)(liang)氣(qi)(qi)體(ti)容量(liang)(liang)的(de)注射針(zhen)筒(tong)。充電(dian)(dian)(dian)用(yong)可調穩(wen)壓電(dian)(dian)(dian)源，用(yong)兩(liang)只四(si)位半數字萬用(yong)表測量(liang)(liang)充電(dian)(dian)(dian)電(dian)(dian)(dian)流和充電(dian)(dian)(dian)電(dian)(dian)(dian)壓。
試驗(yan)時(shi)(shi)間(jian)(jian)是(shi)(shi)在冬季，水溫(wen)5℃。實驗(yan)條(tiao)件是(shi)(shi)統(tong)一用(yong)2A電(dian)(dian)(dian)流充(chong)(chong)(chong)電(dian)(dian)(dian)，最充(chong)(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)壓分別用(yong)43V、44V、45V輪循環依次進行，浮(fu)充(chong)(chong)(chong)轉換電(dian)(dian)(dian)流一律400mA，記錄(lu)下(xia)每次的充(chong)(chong)(chong)電(dian)(dian)(dian)時(shi)(shi)間(jian)(jian)，包括充(chong)(chong)(chong)電(dian)(dian)(dian)末期隨(sui)時(shi)(shi)間(jian)(jian)電(dian)(dian)(dian)流下(xia)降各點數(shu)(shu)據、開始析(xi)氣電(dian)(dian)(dian)壓，按時(shi)(shi)間(jian)(jian)記錄(lu)析(xi)氣量。電(dian)(dian)(dian)池充(chong)(chong)(chong)完后，用(yong)萬分之幾精度的電(dian)(dian)(dian)量臺記錄(lu)放電(dian)(dian)(dian)容(rong)量。充(chong)(chong)(chong)入電(dian)(dian)(dian)量是(shi)(shi)在計算(suan)紙上讀出時(shi)(shi)間(jian)(jian)電(dian)(dian)(dian)流曲線(xian)與坐標之間(jian)(jian)的面積（電(dian)(dian)(dian)容(rong)量就是(shi)(shi)充(chong)(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流對時(shi)(shi)間(jian)(jian)的定積分）。數(shu)(shu)據見下(xia)表：
充號
最高(gao)電壓
V
充電電流
A
浮充電壓V
切換電流A
充入電量Ah
放出電量
Ah
析氣電壓
V
析氣量
mL
溫度℃
1
43
2
41.5
0.4
6.35
6.30
42.6
10
5
2
44
2
41.5
0.4
6.41
6.38
43.0
22
3
45
2
41.5
0.4
6.33
6.31
43.5
160
4
43
2
41.5
0.4
6.52
6.37
42.5
10
5
44
2
41.5
0.4
6.57
6.38
42.5
18
6
45
2
41.5
0.4
6.43
6.39
43
135
備注：該電池組30℃時，放(fang)電(dian)容(rong)量(liang)為(wei)10Ah。
得(de)到試(shi)(shi)(shi)(shi)驗數據后，最(zui)感(gan)到驚(jing)異的(de)(de)(de)是(shi)(shi)(shi)(shi)：充(chong)(chong)(chong)(chong)入電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)的(de)(de)(de)多(duo)(duo)少(shao)(shao)幾乎(hu)與充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)無關。很多(duo)(duo)人認為充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)低(di)(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)會(hui)充(chong)(chong)(chong)(chong)不滿，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)會(hui)提前鹽(yan)化報廢，特(te)別是(shi)(shi)(shi)(shi)在冬季氣(qi)溫較低(di)(di)的(de)(de)(de)時候。而這次試(shi)(shi)(shi)(shi)驗正(zheng)好是(shi)(shi)(shi)(shi)在冬季，水溫只有5℃，試(shi)(shi)(shi)(shi)驗的(de)(de)(de)中(zhong)心電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)值(zhi)是(shi)(shi)(shi)(shi)44V，上(shang)下偏差1V，相對(dui)誤差是(shi)(shi)(shi)(shi)2.3%。在用(yong)43V和45V充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)情(qing)況(kuang)下，充(chong)(chong)(chong)(chong)入電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)和放出電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)相差無幾，與大家(jia)公(gong)認的(de)(de)(de)看法大相徑庭，試(shi)(shi)(shi)(shi)驗是(shi)(shi)(shi)(shi)用(yong)的(de)(de)(de)同(tong)一組電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)，同(tong)樣(yang)的(de)(de)(de)充(chong)(chong)(chong)(chong)、放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)條(tiao)件，輪(lun)番做(zuo)同(tong)樣(yang)的(de)(de)(de)測(ce)試(shi)(shi)(shi)(shi)，實驗數據重復同(tong)樣(yang)的(de)(de)(de)規律，可排除偶然因素干擾，試(shi)(shi)(shi)(shi)驗數據是(shi)(shi)(shi)(shi)準確可信(xin)的(de)(de)(de)。從(cong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)原理上(shang)看，只要(yao)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)高(gao)(gao)于電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)端(duan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)，都(dou)會(hui)給(gei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，一直到電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)中(zhong)的(de)(de)(de)活性物(wu)質(zhi)(zhi)轉(zhuan)換(huan)完(wan)成。充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)最(zui)高(gao)(gao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)，也就(jiu)是(shi)(shi)(shi)(shi)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源開(kai)始由(you)恒流區轉(zhuan)變到恒壓(ya)區，這種轉(zhuan)變是(shi)(shi)(shi)(shi)由(you)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)自身充(chong)(chong)(chong)(chong)入電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)多(duo)(duo)少(shao)(shao)、活性物(wu)質(zhi)(zhi)反應了多(duo)(duo)少(shao)(shao)決定的(de)(de)(de)，充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)的(de)(de)(de)高(gao)(gao)低(di)(di)，僅(jin)是(shi)(shi)(shi)(shi)能(neng)進行(xing)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)化學(xue)反應的(de)(de)(de)條(tiao)件，只要(yao)高(gao)(gao)于電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)開(kai)路電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)就(jiu)會(hui)給(gei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，多(duo)(duo)少(shao)(shao)物(wu)質(zhi)(zhi)能(neng)參與反應由(you)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)自身決定。從(cong)這個思(si)路理解，就(jiu)不難得(de)出，充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)高(gao)(gao)低(di)(di)對(dui)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)容(rong)量(liang)沒有多(duo)(duo)大影響(xiang)。
電池(chi)(chi)在(zai)42.5V～43.5V時(shi)開始析(xi)氣(qi)(qi),而析(xi)氣(qi)(qi)的速度(du)與(yu)(yu)(yu)充(chong)電電壓(ya)有關。到(dao)充(chong)電結束時(shi)，總析(xi)氣(qi)(qi)量(liang)與(yu)(yu)(yu)充(chong)電最(zui)高(gao)電壓(ya)有關，43V與(yu)(yu)(yu)45V總析(xi)氣(qi)(qi)量(liang)相差(cha)10位(wei)（注：以單格允許極限失水10克(ke)，18格相當(dang)240公升氣(qi)(qi)體(ti)，該電池(chi)(chi)45V時(shi)失水并(bing)不大）。 在(zai)充(chong)電末期電流下降(jiang)區時(shi)，只要降(jiang)低電壓(ya)到(dao)42.5V時(shi)，析(xi)氣(qi)(qi)立即停止，這時(shi)充(chong)電電流稍(shao)小(xiao)一點，還會(hui)依著原來的規(gui)律下降(jiang)。
這里對浮充電壓、浮充電流討論一下。對于長期處于浮充狀態下的鉛酸電池組，如后備電源上用的等，對浮充電壓要求是嚴格的。據國處文獻，浮充電壓有-0.2%溫度系數，浮充電壓偏差太大會造成電池鹽化。而電動車用的電池屬循環使用，不是處于這種狀態，不應該用套用浮充狀態使用的條件，充電器設定浮充(chong)的(de)(de)目的(de)(de)僅是免于(yu)充(chong)電(dian)(dian)(dian)(dian)(dian)末期(qi)大量析(xi)氣失水，只(zhi)要把電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)降(jiang)到析(xi)氣點電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)以下，但也不(bu)能低于(yu)電(dian)(dian)(dian)(dian)(dian)池端(duan)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)而停止向(xiang)電(dian)(dian)(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)(dian)(dian)。前面說(shuo)過，在浮充(chong)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)下，充(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流的(de)(de)走勢(shi)基本還是依著原曲(qu)線下降(jiang)，一般還補足5%的(de)(de)容量。所以浮充(chong)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)應在的(de)(de)范圍是低于(yu)析(xi)氣電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)（42.5V），高于(yu)電(dian)(dian)(dian)(dian)(dian)池充(chong)足電(dian)(dian)(dian)(dian)(dian)以后的(de)(de)開路(lu)端(duan)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)（約(yue)40V）。
浮(fu)充(chong)(chong)(chong)(chong)(chong)轉(zhuan)換(huan)電(dian)(dian)(dian)(dian)(dian)流，只(zhi)不過(guo)(guo)(guo)是(shi)(shi)選擇在(zai)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)末期(qi)電(dian)(dian)(dian)(dian)(dian)池(chi)活性(xing)物質反(fan)應接近尾聲，充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流自動下降到某一點(dian)(dian)時，切(qie)換(huan)浮(fu)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)壓(ya)的(de)(de)(de)(de)記號，不少人以(yi)(yi)為浮(fu)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)流高(gao)(gao)了(le)電(dian)(dian)(dian)(dian)(dian)池(chi)會充(chong)(chong)(chong)(chong)(chong)不滿是(shi)(shi)概(gai)念不清，充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)壓(ya)只(zhi)要(yao)高(gao)(gao)于(yu)電(dian)(dian)(dian)(dian)(dian)池(chi)端(duan)電(dian)(dian)(dian)(dian)(dian)壓(ya)，都會對(dui)(dui)電(dian)(dian)(dian)(dian)(dian)池(chi)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)，只(zhi)不過(guo)(guo)(guo)有用(yong)(yong)戶(hu)看到指示燈紅轉(zhuan)綠后(hou)提(ti)前(qian)去用(yong)(yong)電(dian)(dian)(dian)(dian)(dian)池(chi)，這種情況是(shi)(shi)不多的(de)(de)(de)(de)，一般(ban)都是(shi)(shi)夜間(jian)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)，到早(zao)晨綠燈已亮了(le)多時。有的(de)(de)(de)(de)廠家使用(yong)(yong)說(shuo)明書(shu)上(shang)提(ti)醒用(yong)(yong)戶(hu)，在(zai)轉(zhuan)綠燈后(hou)繼續充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)2小時，是(shi)(shi)很好(hao)很正確的(de)(de)(de)(de)。所以(yi)(yi)沒有必要(yao)刻意(yi)去追求(qiu)浮(fu)充(chong)(chong)(chong)(chong)(chong)轉(zhuan)換(huan)點(dian)(dian)的(de)(de)(de)(de)高(gao)(gao)低(di)(di)，一般(ban)新電(dian)(dian)(dian)(dian)(dian)池(chi)末期(qi)電(dian)(dian)(dian)(dian)(dian)流約(yue)為50mA，失(shi)水(shui)以(yi)(yi)后(hou)，酸比增高(gao)(gao)，那時可(ke)達500 mA以(yi)(yi)上(shang)。從析(xi)氣速率與電(dian)(dian)(dian)(dian)(dian)壓(ya)的(de)(de)(de)(de)關系上(shang)來看（上(shang)圖），早(zao)點(dian)(dian)脫離析(xi)氣區為好(hao)，一方面，一方面可(ke)以(yi)(yi)減少析(xi)氣量，另一方面，電(dian)(dian)(dian)(dian)(dian)池(chi)用(yong)(yong)了(le)一段時間(jian)，末期(qi)電(dian)(dian)(dian)(dian)(dian)流增高(gao)(gao)，但還(huan)能低(di)(di)于(yu)我們設定的(de)(de)(de)(de)轉(zhuan)換(huan)點(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流，否(fou)則電(dian)(dian)(dian)(dian)(dian)池(chi)一直在(zai)最高(gao)(gao)電(dian)(dian)(dian)(dian)(dian)壓(ya)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)下，大量失(shi)水(shui)，引發熱(re)控(kong)，充(chong)(chong)(chong)(chong)(chong)脹(zhang)充(chong)(chong)(chong)(chong)(chong)壞電(dian)(dian)(dian)(dian)(dian)池(chi)。有人固執地強調，浮(fu)充(chong)(chong)(chong)(chong)(chong)轉(zhuan)換(huan)點(dian)(dian)高(gao)(gao)電(dian)(dian)(dian)(dian)(dian)池(chi)會欠充(chong)(chong)(chong)(chong)(chong)，前(qian)面已討論過(guo)(guo)(guo)，切(qie)換(huan)到浮(fu)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)壓(ya)后(hou)，不是(shi)(shi)停止充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)了(le)，還(huan)會繼續對(dui)(dui)電(dian)(dian)(dian)(dian)(dian)池(chi)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)(de)，轉(zhuan)換(huan)電(dian)(dian)(dian)(dian)(dian)流適當高(gao)(gao)一點(dian)(dian)有利(li)于(yu)避免過(guo)(guo)(guo)分失(shi)水(shui)和熱(re)失(shi)控(kong)。
至于充電電流的大小設定，先看一下電池制造廠家對10Ah（12Ah）吸附式小型密封電池對充電時的技術要求，通常規定充電速率不要大于0.3C，相當于4A電流，而充電器充電(dian)電(dian)流在(zai)2A左(zuo)右，遠離(li)極限充電(dian)電(dian)流。