看(kan)到消息(xi)說手機(ji)用USB充電，充不滿，而且電量掉得快，搞得不好會(hui)漏電。用直充就沒有這個問題，真的(de)是這樣嗎？ 聽聽果(guo)殼網科學控(kong)的(de)分(fen)析吧。“科學白癡”們(men)可(ke)以(yi)直接跳到最后一段，看(kan)結(jie)論(lun)。

鋰電池的充電方式

   鋰電池的(de)(de)充(chong)電(dian)(dian)(dian)(dian)方式是(shi)限壓(ya)恒流(liu)，都(dou)是(shi)由IC芯片控制的(de)(de)，典型的(de)(de)充(chong)電(dian)(dian)(dian)(dian)方式是(shi)：先(xian)檢(jian)測待充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)池的(de)(de)電(dian)(dian)(dian)(dian)壓(ya)，如果電(dian)(dian)(dian)(dian)壓(ya)低于3V，要先(xian)進(jin)(jin)行(xing)預充(chong)電(dian)(dian)(dian)(dian)，充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)為(wei)設定電(dian)(dian)(dian)(dian)流(liu)的(de)(de)1/10，電(dian)(dian)(dian)(dian)壓(ya)升(sheng)(sheng)到3V后(hou)，進(jin)(jin)入標準充(chong)電(dian)(dian)(dian)(dian)過程。標準充(chong)電(dian)(dian)(dian)(dian)過程為(wei)：以設定電(dian)(dian)(dian)(dian)流(liu)進(jin)(jin)行(xing)恒流(liu)充(chong)電(dian)(dian)(dian)(dian)，電(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)壓(ya)升(sheng)(sheng)到4.20V時，改(gai)為(wei)恒壓(ya)充(chong)電(dian)(dian)(dian)(dian)，保(bao)持(chi)充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)壓(ya)為(wei)4.20V。此時，充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)逐(zhu)漸下降，當電(dian)(dian)(dian)(dian)流(liu)下降至設定充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)的(de)(de)1/10時，充(chong)電(dian)(dian)(dian)(dian)結束。

USB充(chong)電可能沒(mei)充(chong)滿

    電(dian)腦的(de)(de)USB輸出(chu)電(dian)壓(ya)為5V，一般都很(hen)精準，之所以(yi)大家覺得USB充(chong)不滿，是因為USB輸出(chu)電(dian)流(liu)(liu)(liu)小(xiao)，而充(chong)電(dian)的(de)(de)最后階段，需要有涓(juan)流(liu)(liu)(liu)充(chong)電(dian)。涓(juan)流(liu)(liu)(liu)充(chong)電(dian)是用來(lai)彌(mi)補電(dian)池在(zai)充(chong)滿電(dian)后由于自放(fang)電(dian)而造(zao)成(cheng)的(de)(de)容量(liang)損失。電(dian)池在(zai)充(chong)滿電(dian)后，由于自放(fang)電(dian)損失的(de)(de)容量(liang)大約是標稱容量(liang)的(de)(de)5%。理論上說涓(juan)流(liu)(liu)(liu)充(chong)電(dian)要在(zai)充(chong)電(dian)電(dian)流(liu)(liu)(liu)的(de)(de)1/500級別，USB電(dian)流(liu)(liu)(liu)只有500mA，涓(juan)流(liu)(liu)(liu)很(hen)小(xiao)了(le)，所以(yi)這個過程很(hen)慢很(hen)慢，你等不及拔(ba)下來(lai)，5%就沒了(le)。

   用什么充，只(zhi)有電流的區別(bie)

   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(huan)是用電(dian)腦(nao)USB，不都是那(nei)根(gen)線嘛(ma)，用什么充(chong)，只(zhi)有(you)充(chong)電(dian)電(dian)流的區(qu)別，都得捅手機(ji)的“屁股”，只(zhi)要你用USB線充(chong)電(dian)，另(ling)一端是神馬，原理上都是一樣的，只(zhi)是充(chong)得快慢(man)問題。

   經測試，筆記本電(dian)(dian)(dian)腦USB口對手機(ji)充(chong)(chong)電(dian)(dian)(dian)，與座(zuo)充(chong)(chong)對裸手機(ji)電(dian)(dian)(dian)池充(chong)(chong)電(dian)(dian)(dian)相比，充(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)壓(ya)略高（5V:4.2V），充(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流略低（190mA:220mA），但換臺式機(ji)的USB口，充(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)壓(ya)仍為(wei)5V，充(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流漲為(wei)230mA。

   兩種充(chong)電(dian)(dian)方式并無明顯不同，USB充(chong)電(dian)(dian)會漏電(dian)(dian)的說法不正確。