在不同溫度下使用充電器給電池充電
可(ke)充(chong)(chong)電(dian)電(dian)池(chi)可(ke)以在一個較寬(kuan)的(de)溫度(du)范(fan)圍內使用(yong)。然而這并不默認可(ke)在同樣的(de)溫度(du)范(fan)圍內進(jin)行(xing)充(chong)(chong)電(dian)。當無(wu)法避免(mian)在較熱或較冷(leng)的(de)環境(jing)充(chong)(chong)電(dian)時,使用(yong)者必(bi)需對(dui)充(chong)(chong)電(dian)過(guo)程進(jin)行(xing)一些控制。最好還是(shi)讓電(dian)池(chi)在合適的(de)溫度(du)下充(chong)(chong)電(dian)。
鎳(nie)鎘(ge)電池(chi):一般情況下,這種老的電池(chi)技術更能耐受在(zai)(zai)(zai)極端溫(wen)度下充(chong)電。鎳(nie)鎘(ge)電池(chi)能在(zai)(zai)(zai)一小(xiao)時或更短的時間(jian)內快速充(chong)電,但這樣的充(chong)電限(xian)制在(zai)(zai)(zai)5°C到45°C范(fan)圍(wei)內進行,如(ru)在(zai)(zai)(zai)更理想(xiang)的溫(wen)度范(fan)圍(wei)(10°C到25°C)充(chong)電可以得到更好(hao)的效(xiao)果。
在(zai)5°C以(yi)下充(chong)電(dian)(dian)(dian)時(shi)(shi)需要(yao)減(jian)慢充(chong)電(dian)(dian)(dian)速(su)率至0.1C(即標(biao)(biao)稱容量1/10的(de)電(dian)(dian)(dian)流(liu),比如電(dian)(dian)(dian)池(chi)是2000毫(hao)(hao)安(an)小時(shi)(shi)的(de)容量,使用200毫(hao)(hao)安(an)進行充(chong)電(dian)(dian)(dian)),這(zhe)是為了(le)與充(chong)電(dian)(dian)(dian)反應中生成的(de)氫和氧的(de)吸收速(su)率相(xiang)一致(zhi)。由于在(zai)低溫(wen)度時(shi)(shi)氫氧結合速(su)率減(jian)慢,充(chong)的(de)太快會電(dian)(dian)(dian)池(chi)內壓力大幅增加(jia),最(zui)終使電(dian)(dian)(dian)池(chi)排出氣體(ti)。這(zhe)樣(yang)充(chong)過(guo)的(de)電(dian)(dian)(dian)池(chi)以(yi)后(hou)就再也達不到它的(de)標(biao)(biao)稱容量了(le)。
一些需要在低溫時進行快速充電的工業電池內面有一層電熱層以維持電池溫度達到可接受值。一旦充電溫度達到可接受值,充電時發生的氣體結合這一特定過程也能產生一些熱量來輔助保持溫度。理想的充電器能(neng)(neng)自動調整以獲(huo)得氣體結(jie)合與充(chong)電(dian)電(dian)流之間的平衡。(在不放出氣體的情(qing)況下盡可能(neng)(neng)大的充(chong)電(dian)電(dian)流)
鎳氫(qing)電(dian)(dian)池相(xiang)比(bi)鎳鎘(ge)電(dian)(dian)池對(dui)高低溫(wen)下(xia)充(chong)電(dian)(dian)的耐受性要(yao)低許多。鎳氫(qing)電(dian)(dian)池不能(neng)在10°C以下(xia)進行(xing)快速充(chong)電(dian)(dian),在0°C以下(xia)連慢速充(chong)電(dian)(dian)都不行(xing)。一些專門設計的工業充(chong)電(dian)(dian)器(qi)能(neng)調整充(chong)電(dian)(dian)速率以適應(ying)當前的溫(wen)度,民用級消(xiao)費(fei)品由于對(dui)價格敏感,一般不設計成包含溫(wen)度傳感器(qi)的。
在更高的(de)溫(wen)度時,鎳基(ji)電池(chi)的(de)充電接(jie)受力大幅度的(de)下降。在通常室溫(wen)下能提供100%充電容量的(de)電池(chi)在45°C時只能充進75%的(de)容量,在60°C時只能充進45%的(de)容量。這與一些(xie)汽車充電器在夏天(tian)時的(de)低性能相印證(zheng)。
鋰離子電池在(zai)(zai)高低溫度時的性(xing)能都挺好。其可接受的充電溫度范圍是(shi)0°C到45°C。另外推薦在(zai)(zai)0°C到5°C時時將(jiang)充電速(su)率降(jiang)到1C以下。
民(min)用消費級鋰離子電池(chi)(chi)不能在(zai)0度以(yi)下充(chong)電,這(zhe)點很重要(yao)。雖(sui)然(ran)電池(chi)(chi)外(wai)殼在(zai)冰點以(yi)下充(chong)電看起來很正(zheng)常,但電池(chi)(chi)的(de)阻抗會(hui)升高并且電極接受離子的(de)能力(li)急劇下降(jiang)。
最麻煩的(de)是在電(dian)(dian)極上含鋰(li)金屬的(de)部分產(chan)生的(de)電(dian)(dian)鍍(du)反(fan)應。充(chong)電(dian)(dian)速率(lv)越(yue)高,電(dian)(dian)鍍(du)反(fan)應越(yue)顯著,在很低(di)的(de)溫(wen)度(du)下長期充(chong)電(dian)(dian)會對(dui)外殼安全性構(gou)成危害(hai)。電(dian)(dian)鍍(du)反(fan)應的(de)效(xiao)果將(jiang)是永久性的(de),無論經過多少(shao)個充(chong)放循(xun)環都無法(fa)回復。用戶所(suo)不知道的(de)是,這樣(yang)的(de)一(yi)個電(dian)(dian)池將(jiang)變得更易損直至失效(xiao)。如果被(bei)刺破、碾(nian)壓或大速率(lv)充(chong)電(dian)(dian),最終的(de)結果是爆出氣體及火焰(yan)。
優質充電(dian)(dian)器在低(di)溫(wen)時會減小(xiao)充電(dian)(dian)電(dian)(dian)流并且(qie)避免整(zheng)個充電(dian)(dian)過程(cheng)低(di)于0度。在給一個冷電(dian)(dian)池(chi)(chi)充電(dian)(dian)時,可以將外殼(ke)加溫(wen)再充電(dian)(dian)。在低(di)溫(wen)時放電(dian)(dian)不會對鋰(li)離子電(dian)(dian)池(chi)(chi)有什么(me)損害。當然在低(di)溫(wen)環境下整(zheng)個電(dian)(dian)池(chi)(chi)效能的降低(di)也是顯而(er)易(yi)見的。
有些特制的鋰離子電池允(yun)許低溫(wen)充電。這些電池(chi)殼體是用(yong)軍用(yong)材料或(huo)航(hang)空材料制作的。這些電池(chi)的低粘度(du)電解質減少了(le)容量/體積(ji)比率及循(xun)環壽命。除(chu)了(le)低效(xiao)能(neng)外,高價格(ge)也影(ying)響了(le)消費(fei)者對這些產品(pin)的關注。
在高溫環境時使用鋰離子電池也有一些需要(yao)關注(zhu)的(de)(de)安(an)全性問題(ti),尤其是(shi)電(dian)(dian)(dian)(dian)池含有鈷(gu)或鎳電(dian)(dian)(dian)(dian)極時(shi)。把一個充(chong)滿電(dian)(dian)(dian)(dian)的(de)(de)或已經過度充(chong)電(dian)(dian)(dian)(dian)的(de)(de)電(dian)(dian)(dian)(dian)池升(sheng)溫,會導(dao)(dao)(dao)致(zhi)自發性發熱(re)(re)(re)失(shi)控(溫升(sheng)導(dao)(dao)(dao)致(zhi)反應加(jia)快,反應過程放出的(de)(de)熱(re)(re)(re)又導(dao)(dao)(dao)致(zhi)溫度繼續上升(sheng),正反饋循環導(dao)(dao)(dao)致(zhi)失(shi)控)。電(dian)(dian)(dian)(dian)充(chong)的(de)(de)越(yue)滿,導(dao)(dao)(dao)致(zhi)發熱(re)(re)(re)失(shi)控所需要(yao)的(de)(de)熱(re)(re)(re)量就越(yue)少。錳(meng)基(ji)電(dian)(dian)(dian)(dian)池的(de)(de)熱(re)(re)(re)穩(wen)定性更好并且(qie)充(chong)滿電(dian)(dian)(dian)(dian)或過充(chong)時(shi)也不會喪失(shi)穩(wen)定。
鉛酸(suan)電(dian)池能適當(dang)忍受一些極(ji)端溫度,因為我(wo)們對自(zi)己汽車(che)的電(dian)池比較熟(shu)悉。部分耐受性要歸(gui)功于鉛酸(suan)電(dian)池系統的機能遲(chi)鈍(dun)。部分品牌允許零度及以下時充電(dian),其它的則(ze)會承受損害并降(jiang)低(di)容量和縮短(duan)使用壽(shou)命。
為(wei)改善(shan)鉛酸電(dian)(dian)池在低(di)溫時(shi)的(de)(de)充電(dian)(dian)性能以(yi)及避免在升(sheng)溫時(shi)的(de)(de)發(fa)熱(re)失控(kong),控(kong)制充電(dian)(dian)滿(man)時(shi)的(de)(de)電(dian)(dian)壓極限(xian)非(fei)常重要(yao)。進行量(liang)測調整可以(yi)延長電(dian)(dian)池壽(shou)命15%。一般的(de)(de)建議每攝氏度補償量(liang)約(yue)為(wei)3mV。電(dian)(dian)壓調整使用負系數,意即溫度上升(sheng)時(shi)電(dian)(dian)壓的(de)(de)閾值降低(di)。
熱是電池(chi)殺手。電池(chi)越(yue)熱,壽(shou)命越(yue)短。很多情況下升溫無法避免(mian),尤其在快速充電的時候,但盡(jin)量使這個時間(jian)縮(suo)短。在45°C時短時間(jian)充電還(huan)可以(yi)接受,50°C或(huo)以(yi)上(shang)時電池(chi)就開始受損了(le)。請(qing)注(zhu)意電池(chi)殼體(ti)內的溫度總(zong)是比室溫要高幾度的。
超快速充電器
一些充(chong)電(dian)器制造商聲(sheng)稱(cheng)能達到驚人的(de)(de)(de)30分鐘以內的(de)(de)(de)充(chong)電(dian)時間(jian)。使用平衡的(de)(de)(de)很好的(de)(de)(de)電(dian)池并在適度的(de)(de)(de)室(shi)溫下進行操作,專為快(kuai)速(su)充(chong)電(dian)設計的(de)(de)(de)鎳鎘電(dian)池的(de)(de)(de)確(que)能達到這(zhe)么快(kuai)的(de)(de)(de)速(su)度。要達到這(zhe)個速(su)度,只(zhi)需要通(tong)過大電(dian)流充(chong)電(dian)先(xian)充(chong)到70%的(de)(de)(de)充(chong)電(dian)周(zhou)期。
在充(chong)電(dian)(dian)周期的(de)(de)第二階段,充(chong)電(dian)(dian)電(dian)(dian)流必需(xu)減少(shao)。吸(xi)收電(dian)(dian)能的(de)(de)效(xiao)率在電(dian)(dian)池快充(chong)滿時逐漸降(jiang)低。在充(chong)電(dian)(dian)周期后半段如果仍保(bao)持大電(dian)(dian)流,多余的(de)(de)能量就會轉(zhuan)化成熱(re)量及很高的(de)(de)電(dian)(dian)池壓力(li)。最后導(dao)致排(pai)氣,放出氧氣及氫氣。放出氣體不僅會耗損電(dian)(dian)解質,它們還都是易(yi)燃的(de)(de)!白色粉(fen)狀物(wu)在排(pai)氣孔(kong)周圍積聚(ju)表明之前發生過排(pai)氣。
超快速充(chong)(chong)電(dian)(dian)只能應用(yong)(yong)(yong)于專門為快速充(chong)(chong)電(dian)(dian)設(she)計的(de)(de)電(dian)(dian)池(chi)。對(dui)普通充(chong)(chong)電(dian)(dian)電(dian)(dian)池(chi)進(jin)行這種大電(dian)(dian)流(liu)充(chong)(chong)電(dian)(dian)會使導(dao)電(dian)(dian)通路被加熱(re)。對(dui)于一些使用(yong)(yong)(yong)彈簧式壓緊電(dian)(dian)極的(de)(de)電(dian)(dian)池(chi)盒,電(dian)(dian)池(chi)在和電(dian)(dian)極接觸(chu)處(chu)的(de)(de)發熱(re)效應被低估了。這些接觸(chu)處(chu)使用(yong)(yong)(yong)大電(dian)(dian)流(liu)充(chong)(chong)電(dian)(dian)可能產生永久損傷。通常,一個細小的(de)(de)幾乎不可見的(de)(de)焊坑會產生在接觸(chu)處(chu)尖端(duan),繼而導(dao)至電(dian)(dian)路阻(zu)抗(kang)上升或(huo)接觸(chu)不良斷(duan)路。不良接觸(chu)處(chu)在大電(dian)(dian)流(liu)下產生的(de)(de)熱(re)量(liang)一般會導(dao)致塑料熔(rong)化。較高的(de)(de)接觸(chu)壓緊力可以減少電(dian)(dian)阻(zu)和熱(re)量(liang)。
老(lao)舊(jiu)的(de)(de)充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)池(chi)有(you)較(jiao)大的(de)(de)內阻,所(suo)以(yi)不配對的(de)(de)電(dian)(dian)(dian)池(chi)不能放一起進行快(kuai)速充(chong)電(dian)(dian)(dian)。即使它們(men)都是(shi)快(kuai)充(chong)型(xing)電(dian)(dian)(dian)池(chi)。內阻大的(de)(de)電(dian)(dian)(dian)池(chi)生熱(re)快(kuai),從(cong)而使電(dian)(dian)(dian)池(chi)狀況(kuang)繼續惡(e)化。差的(de)(de)(舊(jiu)的(de)(de))電(dian)(dian)(dian)池(chi)容量也降低了,它們(men)比正常電(dian)(dian)(dian)池(chi)更早充(chong)滿并(bing)開始快(kuai)速升溫(wen)。一些(xie)電(dian)(dian)(dian)池(chi)產生的(de)(de)熱(re)量足(zu)以(yi)讓塑料電(dian)(dian)(dian)池(chi)盒軟(ruan)化變形。
許多制造商還提供脈沖充電器。在充(chong)(chong)電脈沖之間分(fen)布放電脈沖可(ke)以(yi)很大的提(ti)升充(chong)(chong)電效果。這個方法促進了(le)氧氣和氫(qing)氣的重新結(jie)合,使內(nei)壓和溫(wen)度降低。脈沖充(chong)(chong)電還(huan)能(neng)減(jian)少(shao)鎳鎘電池結(jie)晶效應(ying)(記憶效應(ying))。多數用于鎳基電池的Cadex充(chong)(chong)電器都使用了(le)這種技術(shu)。
一些(xie)高(gao)級充(chong)電(dian)(dian)(dian)(dian)器能(neng)根(gen)據(ju)電(dian)(dian)(dian)(dian)池特性調整充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)。一個空的(de)充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)池先使用大(da)電(dian)(dian)(dian)(dian)流(liu)充(chong),在充(chong)到(dao)大(da)半時(shi),電(dian)(dian)(dian)(dian)流(liu)逐漸縮小。舊電(dian)(dian)(dian)(dian)池也能(neng)根(gen)據(ju)情況(kuang)自(zi)動充(chong)到(dao)一個合適的(de)程(cheng)度。
