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)規定電(dian)壓(ya)高0.1V，電(dian)池(chi)因此熱失(shi)控而充(chong)(chong)(chong)脹了；也(ye)接到(dao)通知說：電(dian)壓(ya)比(bi)規定定低0.1V，電(dian)池(chi)欠充(chong)(chong)(chong)，提(ti)前報廢。一個(ge)千(qian)分之(zhi)幾的誤差造(zao)成如此嚴重(zhong)后(hou)果(guo)，真(zhen)是失(shi)之(zhi)毫(hao)厘(li)，謬(miu)之(zhi)千(qian)里之(zhi)外，鉛酸蓄電(dian)池(chi)果(guo)真(zhen)有(you)這(zhe)么神秘嗎？為了解開(kai)困擾(rao)電(dian)動車(che)充(chong)(chong)(chong)電(dian)中(zhong)的這(zhe)個(ge)謎團，做如下(xia)實(shi)驗。
用一(yi)個水(shui)槽盛滿(man)水(shui)，電(dian)(dian)(dian)池放在水(shui)中，在電(dian)(dian)(dian)池上方有一(yi)個收集氣(qi)體用的(de)(de)倒扣的(de)(de)漏斗，漏斗頂端裝有可以計(ji)量(liang)氣(qi)體容(rong)量(liang)的(de)(de)注射針筒(tong)。充(chong)電(dian)(dian)(dian)用可調穩壓電(dian)(dian)(dian)源，用兩只四(si)位半(ban)數字萬用表(biao)測(ce)量(liang)充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)和充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)壓。
試(shi)驗(yan)時(shi)間(jian)是在冬(dong)季(ji)，水溫(wen)5℃。實(shi)驗(yan)條件是統(tong)一用2A電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)，最充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)壓分(fen)別用43V、44V、45V輪(lun)循(xun)環依次(ci)進行，浮充(chong)(chong)轉換電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)一律400mA，記錄(lu)下(xia)每次(ci)的(de)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)時(shi)間(jian)，包括(kuo)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)末期隨時(shi)間(jian)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)下(xia)降各點(dian)數據、開始析氣電(dian)(dian)(dian)(dian)(dian)壓，按(an)時(shi)間(jian)記錄(lu)析氣量。電(dian)(dian)(dian)(dian)(dian)池充(chong)(chong)完后，用萬分(fen)之(zhi)幾精度的(de)電(dian)(dian)(dian)(dian)(dian)量臺(tai)記錄(lu)放電(dian)(dian)(dian)(dian)(dian)容(rong)量。充(chong)(chong)入電(dian)(dian)(dian)(dian)(dian)量是在計算紙(zhi)上讀出時(shi)間(jian)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)曲線(xian)與坐標之(zhi)間(jian)的(de)面(mian)積(ji)（電(dian)(dian)(dian)(dian)(dian)容(rong)量就(jiu)是充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)對時(shi)間(jian)的(de)定積(ji)分(fen)）。數據見下(xia)表：
充(chong)號(hao)
最高電壓
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(shi)，放電容量為(wei)10Ah。
得(de)(de)到(dao)試驗(yan)數據后，最感(gan)到(dao)驚異(yi)的(de)(de)(de)是(shi)(shi)(shi)：充(chong)(chong)(chong)(chong)(chong)入電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)(liang)的(de)(de)(de)多(duo)(duo)少(shao)幾乎與(yu)充(chong)(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(wu)關。很(hen)多(duo)(duo)人(ren)認(ren)為(wei)充(chong)(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)低電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)會(hui)(hui)充(chong)(chong)(chong)(chong)(chong)不(bu)滿(man)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)會(hui)(hui)提前鹽化報廢，特別是(shi)(shi)(shi)在(zai)冬季氣溫較低的(de)(de)(de)時(shi)候。而這(zhe)次試驗(yan)正好是(shi)(shi)(shi)在(zai)冬季，水溫只(zhi)有5℃，試驗(yan)的(de)(de)(de)中心電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)值是(shi)(shi)(shi)44V，上下偏差(cha)1V，相(xiang)對誤差(cha)是(shi)(shi)(shi)2.3%。在(zai)用43V和45V充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)情況下，充(chong)(chong)(chong)(chong)(chong)入電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)(liang)和放(fang)出(chu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)(liang)相(xiang)差(cha)無(wu)幾，與(yu)大(da)家公認(ren)的(de)(de)(de)看法(fa)大(da)相(xiang)徑庭，試驗(yan)是(shi)(shi)(shi)用的(de)(de)(de)同一組電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)，同樣的(de)(de)(de)充(chong)(chong)(chong)(chong)(chong)、放(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)條件，輪番做同樣的(de)(de)(de)測試，實驗(yan)數據重復(fu)同樣的(de)(de)(de)規律，可排除偶然(ran)因素干擾(rao)，試驗(yan)數據是(shi)(shi)(shi)準確可信的(de)(de)(de)。從電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)原理上看，只(zhi)要充(chong)(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(yu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)端電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)，都(dou)會(hui)(hui)給(gei)(gei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，一直到(dao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)中的(de)(de)(de)活性物(wu)(wu)(wu)質轉換完(wan)成。充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)最高(gao)(gao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)，也(ye)就(jiu)是(shi)(shi)(shi)充(chong)(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(shi)由(you)(you)恒(heng)(heng)流區(qu)(qu)轉變到(dao)恒(heng)(heng)壓(ya)區(qu)(qu)，這(zhe)種轉變是(shi)(shi)(shi)由(you)(you)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)自身充(chong)(chong)(chong)(chong)(chong)入電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)(liang)多(duo)(duo)少(shao)、活性物(wu)(wu)(wu)質反應了多(duo)(duo)少(shao)決定的(de)(de)(de)，充(chong)(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，僅(jin)是(shi)(shi)(shi)能(neng)進行電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)化學反應的(de)(de)(de)條件，只(zhi)要高(gao)(gao)于(yu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)開(kai)路電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)就(jiu)會(hui)(hui)給(gei)(gei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，多(duo)(duo)少(shao)物(wu)(wu)(wu)質能(neng)參與(yu)反應由(you)(you)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)自身決定。從這(zhe)個(ge)思(si)路理解，就(jiu)不(bu)難得(de)(de)出(chu)，充(chong)(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)低對電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)容量(liang)(liang)沒有多(duo)(duo)大(da)影響。
電(dian)(dian)池在42.5V～43.5V時(shi)(shi)開始析(xi)(xi)氣,而析(xi)(xi)氣的速(su)度與(yu)充電(dian)(dian)電(dian)(dian)壓有關。到充電(dian)(dian)結束(shu)時(shi)(shi)，總析(xi)(xi)氣量與(yu)充電(dian)(dian)最(zui)高(gao)電(dian)(dian)壓有關，43V與(yu)45V總析(xi)(xi)氣量相(xiang)差10位(wei)（注：以單格允(yun)許(xu)極(ji)限失(shi)水(shui)(shui)10克，18格相(xiang)當240公升(sheng)氣體(ti)，該電(dian)(dian)池45V時(shi)(shi)失(shi)水(shui)(shui)并不大）。 在充電(dian)(dian)末期電(dian)(dian)流下降(jiang)區時(shi)(shi)，只要降(jiang)低(di)電(dian)(dian)壓到42.5V時(shi)(shi)，析(xi)(xi)氣立即(ji)停止，這時(shi)(shi)充電(dian)(dian)電(dian)(dian)流稍小一(yi)點(dian)，還(huan)會依(yi)著原來的規律(lv)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(ding)浮(fu)充(chong)的目的僅(jin)是(shi)免于充(chong)電(dian)(dian)末期大量析(xi)氣(qi)失水，只要把電(dian)(dian)壓降到析(xi)氣(qi)點(dian)電(dian)(dian)壓以下，但(dan)也不能低(di)于電(dian)(dian)池端(duan)電(dian)(dian)壓而停止向電(dian)(dian)池充(chong)電(dian)(dian)。前面說過，在浮(fu)充(chong)電(dian)(dian)壓下，充(chong)電(dian)(dian)電(dian)(dian)流的走(zou)勢基本還(huan)是(shi)依(yi)著原曲線(xian)下降，一般還(huan)補足5%的容量。所以浮(fu)充(chong)電(dian)(dian)壓應在的范圍是(shi)低(di)于析(xi)氣(qi)電(dian)(dian)壓（42.5V），高(gao)于電(dian)(dian)池充(chong)足電(dian)(dian)以后(hou)的開路端(duan)電(dian)(dian)壓（約40V）。
浮(fu)充(chong)(chong)(chong)(chong)(chong)轉(zhuan)(zhuan)換(huan)(huan)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)，只(zhi)不過(guo)(guo)是(shi)選擇在(zai)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)末期(qi)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)活(huo)性(xing)物質反(fan)應接近尾(wei)聲，充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)自動(dong)下降到(dao)某一點(dian)時(shi)，切換(huan)(huan)浮(fu)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)的記(ji)號，不少人以(yi)(yi)為(wei)(wei)浮(fu)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)高(gao)(gao)了(le)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)會(hui)充(chong)(chong)(chong)(chong)(chong)不滿是(shi)概(gai)念不清(qing)，充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)只(zhi)要高(gao)(gao)于(yu)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)端電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)，都會(hui)對電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)，只(zhi)不過(guo)(guo)有用(yong)(yong)戶看到(dao)指示燈紅轉(zhuan)(zhuan)綠(lv)后(hou)提前(qian)去用(yong)(yong)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)，這種(zhong)情況是(shi)不多的，一般(ban)(ban)都是(shi)夜間(jian)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)，到(dao)早晨綠(lv)燈已亮了(le)多時(shi)。有的廠家使用(yong)(yong)說明(ming)書上(shang)提醒用(yong)(yong)戶，在(zai)轉(zhuan)(zhuan)綠(lv)燈后(hou)繼續充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)2小時(shi)，是(shi)很(hen)好(hao)很(hen)正確的。所以(yi)(yi)沒有必要刻意去追求浮(fu)充(chong)(chong)(chong)(chong)(chong)轉(zhuan)(zhuan)換(huan)(huan)點(dian)的高(gao)(gao)低(di)，一般(ban)(ban)新電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)末期(qi)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)約為(wei)(wei)50mA，失(shi)(shi)水(shui)(shui)以(yi)(yi)后(hou)，酸比增高(gao)(gao)，那時(shi)可達500 mA以(yi)(yi)上(shang)。從析(xi)氣(qi)(qi)速率與(yu)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)的關系上(shang)來看（上(shang)圖），早點(dian)脫(tuo)離析(xi)氣(qi)(qi)區為(wei)(wei)好(hao)，一方(fang)面(mian)(mian)，一方(fang)面(mian)(mian)可以(yi)(yi)減少析(xi)氣(qi)(qi)量(liang)，另(ling)一方(fang)面(mian)(mian)，電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)用(yong)(yong)了(le)一段時(shi)間(jian)，末期(qi)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)增高(gao)(gao)，但還(huan)能低(di)于(yu)我(wo)們設定的轉(zhuan)(zhuan)換(huan)(huan)點(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)，否則電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)一直在(zai)最高(gao)(gao)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)下，大量(liang)失(shi)(shi)水(shui)(shui)，引發熱(re)控，充(chong)(chong)(chong)(chong)(chong)脹(zhang)充(chong)(chong)(chong)(chong)(chong)壞電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)。有人固執地強調(diao)，浮(fu)充(chong)(chong)(chong)(chong)(chong)轉(zhuan)(zhuan)換(huan)(huan)點(dian)高(gao)(gao)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)會(hui)欠充(chong)(chong)(chong)(chong)(chong)，前(qian)面(mian)(mian)已討論過(guo)(guo)，切換(huan)(huan)到(dao)浮(fu)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)后(hou)，不是(shi)停(ting)止充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)了(le)，還(huan)會(hui)繼續對電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)的，轉(zhuan)(zhuan)換(huan)(huan)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)適當(dang)高(gao)(gao)一點(dian)有利于(yu)避免過(guo)(guo)分失(shi)(shi)水(shui)(shui)和熱(re)失(shi)(shi)控。
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)(dian)電(dian)(dian)流在(zai)2A左右，遠離極限充電(dian)(dian)電(dian)(dian)流。