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(bi)規定(ding)電壓(ya)高(gao)0.1V，電池因此熱(re)失控(kong)而充脹了；也接到通知說：電壓(ya)比(bi)規定(ding)定(ding)低0.1V，電池欠充，提前報廢。一個(ge)千(qian)(qian)分之幾的誤差造成如此嚴(yan)重后果(guo)，真是失之毫厘(li)，謬之千(qian)(qian)里之外，鉛酸蓄電池果(guo)真有這(zhe)(zhe)么神秘嗎？為了解開困擾(rao)電動車充電中的這(zhe)(zhe)個(ge)謎團，做如下實驗。
用(yong)一個(ge)水(shui)(shui)槽盛滿水(shui)(shui)，電(dian)(dian)(dian)池放(fang)在(zai)水(shui)(shui)中，在(zai)電(dian)(dian)(dian)池上方(fang)有一個(ge)收集氣(qi)體用(yong)的(de)(de)倒扣的(de)(de)漏(lou)斗，漏(lou)斗頂端裝有可以(yi)計量(liang)(liang)氣(qi)體容(rong)量(liang)(liang)的(de)(de)注射針(zhen)筒(tong)。充(chong)電(dian)(dian)(dian)用(yong)可調穩壓電(dian)(dian)(dian)源(yuan)，用(yong)兩只四位半(ban)數(shu)字萬用(yong)表測量(liang)(liang)充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流和充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)壓。
試驗(yan)時間是(shi)在(zai)冬季(ji)，水溫5℃。實驗(yan)條(tiao)件是(shi)統一用(yong)2A電(dian)(dian)(dian)(dian)流充(chong)電(dian)(dian)(dian)(dian)，最充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)壓(ya)分別用(yong)43V、44V、45V輪(lun)循環依次進行，浮(fu)充(chong)轉(zhuan)換電(dian)(dian)(dian)(dian)流一律400mA，記(ji)錄(lu)(lu)下(xia)每次的充(chong)電(dian)(dian)(dian)(dian)時間，包(bao)括充(chong)電(dian)(dian)(dian)(dian)末期隨時間電(dian)(dian)(dian)(dian)流下(xia)降各點數(shu)據、開始析(xi)氣電(dian)(dian)(dian)(dian)壓(ya)，按時間記(ji)錄(lu)(lu)析(xi)氣量(liang)。電(dian)(dian)(dian)(dian)池充(chong)完后，用(yong)萬分之幾精度的電(dian)(dian)(dian)(dian)量(liang)臺記(ji)錄(lu)(lu)放電(dian)(dian)(dian)(dian)容量(liang)。充(chong)入電(dian)(dian)(dian)(dian)量(liang)是(shi)在(zai)計算紙上讀出時間電(dian)(dian)(dian)(dian)流曲線與(yu)坐標(biao)之間的面(mian)積(ji)（電(dian)(dian)(dian)(dian)容量(liang)就是(shi)充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流對時間的定積(ji)分）。數(shu)據見(jian)下(xia)表：
充號(hao)
最(zui)高電壓
V
充電電流
A
浮充電壓V
切換電流A
充入電量Ah
放出(chu)電量
Ah
析氣電(dian)壓
V
析氣量(liang)
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)電容量為10Ah。
得(de)到試驗(yan)數據(ju)后，最感到驚異的(de)(de)(de)是(shi)(shi)(shi)(shi)：充(chong)入(ru)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)的(de)(de)(de)多(duo)少幾乎與(yu)(yu)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)無(wu)關(guan)。很(hen)多(duo)人認為充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)低(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)會(hui)充(chong)不滿(man)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)會(hui)提前鹽化(hua)報(bao)廢(fei)，特別(bie)是(shi)(shi)(shi)(shi)在(zai)冬季氣溫較低(di)的(de)(de)(de)時(shi)候。而這(zhe)次試驗(yan)正好(hao)是(shi)(shi)(shi)(shi)在(zai)冬季，水溫只有5℃，試驗(yan)的(de)(de)(de)中心電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)值(zhi)是(shi)(shi)(shi)(shi)44V，上下偏差1V，相對誤差是(shi)(shi)(shi)(shi)2.3%。在(zai)用43V和45V充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)情況(kuang)下，充(chong)入(ru)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)和放出(chu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)相差無(wu)幾，與(yu)(yu)大家公認的(de)(de)(de)看(kan)法大相徑庭，試驗(yan)是(shi)(shi)(shi)(shi)用的(de)(de)(de)同(tong)(tong)一(yi)組電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)，同(tong)(tong)樣(yang)的(de)(de)(de)充(chong)、放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)條(tiao)件(jian)，輪番做同(tong)(tong)樣(yang)的(de)(de)(de)測試，實驗(yan)數據(ju)重復同(tong)(tong)樣(yang)的(de)(de)(de)規(gui)律，可排除偶然因素干擾，試驗(yan)數據(ju)是(shi)(shi)(shi)(shi)準(zhun)確可信(xin)的(de)(de)(de)。從(cong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)原理上看(kan)，只要充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)高于電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)端(duan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)，都會(hui)給電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，一(yi)直到電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)中的(de)(de)(de)活性物(wu)質轉換完成。充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)最高電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)，也就(jiu)是(shi)(shi)(shi)(shi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源開始(shi)由(you)(you)恒(heng)流區(qu)轉變(bian)到恒(heng)壓(ya)(ya)區(qu)，這(zhe)種(zhong)轉變(bian)是(shi)(shi)(shi)(shi)由(you)(you)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)自身(shen)(shen)充(chong)入(ru)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)多(duo)少、活性物(wu)質反應了多(duo)少決定的(de)(de)(de)，充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)的(de)(de)(de)高低(di)，僅(jin)是(shi)(shi)(shi)(shi)能進行電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)化(hua)學反應的(de)(de)(de)條(tiao)件(jian)，只要高于電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)開路電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)就(jiu)會(hui)給電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，多(duo)少物(wu)質能參(can)與(yu)(yu)反應由(you)(you)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)自身(shen)(shen)決定。從(cong)這(zhe)個(ge)思(si)路理解，就(jiu)不難(nan)得(de)出(chu)，充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)高低(di)對電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)容量(liang)沒(mei)有多(duo)大影響。
電(dian)池(chi)在42.5V～43.5V時開始(shi)析(xi)氣(qi)(qi),而析(xi)氣(qi)(qi)的(de)速度與充(chong)電(dian)電(dian)壓有(you)關(guan)。到(dao)充(chong)電(dian)結束時，總(zong)析(xi)氣(qi)(qi)量與充(chong)電(dian)最高(gao)電(dian)壓有(you)關(guan)，43V與45V總(zong)析(xi)氣(qi)(qi)量相(xiang)差10位（注：以單格允許極限失(shi)水(shui)10克，18格相(xiang)當240公升氣(qi)(qi)體，該電(dian)池(chi)45V時失(shi)水(shui)并不大）。 在充(chong)電(dian)末(mo)期電(dian)流(liu)下降(jiang)區(qu)時，只要(yao)降(jiang)低(di)電(dian)壓到(dao)42.5V時，析(xi)氣(qi)(qi)立即停(ting)止，這時充(chong)電(dian)電(dian)流(liu)稍(shao)小一點(dian)，還會依著原來的(de)規律下降(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(fu)充的(de)目的(de)僅是(shi)(shi)免(mian)于充電末(mo)期(qi)大量析氣失水，只要把電壓(ya)(ya)降到(dao)析氣點電壓(ya)(ya)以下，但也(ye)不能低于電池端電壓(ya)(ya)而停止向電池充電。前面說過，在浮(fu)充電壓(ya)(ya)下，充電電流(liu)的(de)走勢基本還是(shi)(shi)依著原曲(qu)線(xian)下降，一般還補足5%的(de)容(rong)量。所(suo)以浮(fu)充電壓(ya)(ya)應在的(de)范圍(wei)是(shi)(shi)低于析氣電壓(ya)(ya)（42.5V），高于電池充足電以后的(de)開(kai)路(lu)端電壓(ya)(ya)（約40V）。
浮(fu)充(chong)(chong)(chong)轉(zhuan)換(huan)(huan)(huan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)，只不(bu)過(guo)(guo)是(shi)(shi)選(xuan)擇在(zai)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)末(mo)(mo)期(qi)(qi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池活性物質反應接近(jin)尾聲，充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)自動(dong)下降(jiang)到(dao)某一(yi)(yi)點(dian)(dian)(dian)時，切換(huan)(huan)(huan)浮(fu)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)的(de)(de)記號，不(bu)少(shao)人(ren)以為(wei)浮(fu)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)高(gao)了電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池會(hui)充(chong)(chong)(chong)不(bu)滿是(shi)(shi)概念不(bu)清，充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)只要(yao)高(gao)于(yu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池端電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)，都(dou)會(hui)對電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，只不(bu)過(guo)(guo)有(you)用(yong)戶看到(dao)指示燈紅(hong)轉(zhuan)綠(lv)后(hou)提前去(qu)用(yong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池，這(zhe)種情況是(shi)(shi)不(bu)多的(de)(de)，一(yi)(yi)般都(dou)是(shi)(shi)夜間(jian)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，到(dao)早晨綠(lv)燈已亮了多時。有(you)的(de)(de)廠家(jia)使用(yong)說(shuo)明書上(shang)(shang)(shang)提醒用(yong)戶，在(zai)轉(zhuan)綠(lv)燈后(hou)繼續(xu)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)2小(xiao)時，是(shi)(shi)很好很正確的(de)(de)。所以沒(mei)有(you)必(bi)要(yao)刻意去(qu)追(zhui)求浮(fu)充(chong)(chong)(chong)轉(zhuan)換(huan)(huan)(huan)點(dian)(dian)(dian)的(de)(de)高(gao)低，一(yi)(yi)般新電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池末(mo)(mo)期(qi)(qi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)約為(wei)50mA，失水以后(hou)，酸比增(zeng)高(gao)，那時可達500 mA以上(shang)(shang)(shang)。從析(xi)氣速率與電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)的(de)(de)關系上(shang)(shang)(shang)來看（上(shang)(shang)(shang)圖），早點(dian)(dian)(dian)脫離析(xi)氣區為(wei)好，一(yi)(yi)方面(mian)，一(yi)(yi)方面(mian)可以減少(shao)析(xi)氣量，另一(yi)(yi)方面(mian)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池用(yong)了一(yi)(yi)段時間(jian)，末(mo)(mo)期(qi)(qi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)增(zeng)高(gao)，但還(huan)能低于(yu)我們設(she)定的(de)(de)轉(zhuan)換(huan)(huan)(huan)點(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)，否(fou)則電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池一(yi)(yi)直在(zai)最高(gao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)下，大量失水，引發熱控(kong)，充(chong)(chong)(chong)脹充(chong)(chong)(chong)壞(huai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池。有(you)人(ren)固(gu)執地強調，浮(fu)充(chong)(chong)(chong)轉(zhuan)換(huan)(huan)(huan)點(dian)(dian)(dian)高(gao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池會(hui)欠充(chong)(chong)(chong)，前面(mian)已討(tao)論過(guo)(guo)，切換(huan)(huan)(huan)到(dao)浮(fu)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)后(hou)，不(bu)是(shi)(shi)停止充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)了，還(huan)會(hui)繼續(xu)對電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)，轉(zhuan)換(huan)(huan)(huan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)適當高(gao)一(yi)(yi)點(dian)(dian)(dian)有(you)利于(yu)避免過(guo)(guo)分失水和熱失控(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2A左右，遠離(li)極(ji)限充電(dian)電(dian)流。