看到(dao)消息說手(shou)機用USB充(chong)電(dian)，充(chong)不滿，而且電(dian)量掉(diao)得快，搞得不好會(hui)漏電(dian)。用直(zhi)充(chong)就沒有(you)這個問(wen)題，真(zhen)的是這樣(yang)嗎？ 聽(ting)聽(ting)果殼網科學控的分析(xi)吧。“科學白癡”們可以(yi)直(zhi)接(jie)跳到(dao)最后(hou)一段，看結論。

鋰電池的充電方式

   鋰電池的(de)(de)充(chong)(chong)(chong)電(dian)方式(shi)是限壓(ya)(ya)恒(heng)流(liu)(liu)，都是由IC芯(xin)片控制(zhi)的(de)(de)，典型(xing)的(de)(de)充(chong)(chong)(chong)電(dian)方式(shi)是：先(xian)檢測待充(chong)(chong)(chong)電(dian)電(dian)池(chi)的(de)(de)電(dian)壓(ya)(ya)，如果(guo)電(dian)壓(ya)(ya)低于3V，要先(xian)進行預充(chong)(chong)(chong)電(dian)，充(chong)(chong)(chong)電(dian)電(dian)流(liu)(liu)為(wei)(wei)(wei)設(she)定(ding)(ding)電(dian)流(liu)(liu)的(de)(de)1/10，電(dian)壓(ya)(ya)升到3V后(hou)，進入(ru)標準充(chong)(chong)(chong)電(dian)過(guo)程(cheng)。標準充(chong)(chong)(chong)電(dian)過(guo)程(cheng)為(wei)(wei)(wei)：以設(she)定(ding)(ding)電(dian)流(liu)(liu)進行恒(heng)流(liu)(liu)充(chong)(chong)(chong)電(dian)，電(dian)池(chi)電(dian)壓(ya)(ya)升到4.20V時，改為(wei)(wei)(wei)恒(heng)壓(ya)(ya)充(chong)(chong)(chong)電(dian)，保持充(chong)(chong)(chong)電(dian)電(dian)壓(ya)(ya)為(wei)(wei)(wei)4.20V。此時，充(chong)(chong)(chong)電(dian)電(dian)流(liu)(liu)逐漸下(xia)降(jiang)，當(dang)電(dian)流(liu)(liu)下(xia)降(jiang)至設(she)定(ding)(ding)充(chong)(chong)(chong)電(dian)電(dian)流(liu)(liu)的(de)(de)1/10時，充(chong)(chong)(chong)電(dian)結束。

USB充電可能沒充滿

    電(dian)腦的(de)USB輸出電(dian)壓為(wei)5V，一(yi)般都很(hen)精(jing)準，之所以大家覺得(de)USB充不(bu)滿，是因為(wei)USB輸出電(dian)流(liu)小，而充電(dian)的(de)最后階段(duan)，需要(yao)有(you)(you)涓流(liu)充電(dian)。涓流(liu)充電(dian)是用來彌補電(dian)池在(zai)充滿電(dian)后由(you)(you)于自放電(dian)而造成(cheng)的(de)容量損失(shi)。電(dian)池在(zai)充滿電(dian)后，由(you)(you)于自放電(dian)損失(shi)的(de)容量大約是標稱(cheng)容量的(de)5%。理(li)論上(shang)說涓流(liu)充電(dian)要(yao)在(zai)充電(dian)電(dian)流(liu)的(de)1/500級別(bie)，USB電(dian)流(liu)只有(you)(you)500mA，涓流(liu)很(hen)小了(le)，所以這(zhe)個過程(cheng)很(hen)慢很(hen)慢，你等不(bu)及拔(ba)下來，5%就沒了(le)。

   用什么充，只有電流(liu)的區別

   另外手機數碼產品的鋰電池都有保護板，有限制最低電壓和限制充電電流的作用。而且現在的手機無論是用充電器還是(shi)用(yong)電(dian)(dian)腦USB，不都(dou)是(shi)那根線嘛，用(yong)什么充，只(zhi)有充電(dian)(dian)電(dian)(dian)流的區別，都(dou)得捅手機的“屁股”，只(zhi)要你用(yong)USB線充電(dian)(dian)，另一端(duan)是(shi)神馬，原(yuan)理(li)上(shang)都(dou)是(shi)一樣(yang)的，只(zhi)是(shi)充得快慢問題。

   經測試，筆記本(ben)電(dian)(dian)(dian)腦USB口(kou)對(dui)手機充電(dian)(dian)(dian)，與座充對(dui)裸手機電(dian)(dian)(dian)池充電(dian)(dian)(dian)相比(bi)，充電(dian)(dian)(dian)電(dian)(dian)(dian)壓略高（5V:4.2V），充電(dian)(dian)(dian)電(dian)(dian)(dian)流略低(di)（190mA:220mA），但(dan)換臺式機的USB口(kou)，充電(dian)(dian)(dian)電(dian)(dian)(dian)壓仍為5V，充電(dian)(dian)(dian)電(dian)(dian)(dian)流漲(zhang)為230mA。

   兩種充(chong)(chong)電(dian)(dian)方式并(bing)無明顯不同(tong)，USB充(chong)(chong)電(dian)(dian)會(hui)漏電(dian)(dian)的(de)說法不正確。