看(kan)到消(xiao)息說手機用USB充電，充不滿，而且電量掉得(de)快，搞得(de)不好會漏電。用直充就沒(mei)有(you)這個問題(ti)，真(zhen)的是(shi)這樣嗎？ 聽聽果殼網科學控的分析吧。“科學白癡”們可以直接跳到最后一段，看(kan)結論。

鋰電池的充電方式

   鋰電池的(de)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)方式是(shi)限壓(ya)恒(heng)流(liu)(liu)(liu)，都(dou)是(shi)由IC芯片控制的(de)，典型的(de)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)方式是(shi)：先檢測(ce)待(dai)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)池的(de)電(dian)(dian)(dian)(dian)壓(ya)，如果電(dian)(dian)(dian)(dian)壓(ya)低于3V，要(yao)先進行(xing)預(yu)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)，充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)為(wei)(wei)設定電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)的(de)1/10，電(dian)(dian)(dian)(dian)壓(ya)升(sheng)到3V后，進入(ru)標準充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)過程(cheng)。標準充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)過程(cheng)為(wei)(wei)：以(yi)設定電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)進行(xing)恒(heng)流(liu)(liu)(liu)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)，電(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)壓(ya)升(sheng)到4.20V時，改為(wei)(wei)恒(heng)壓(ya)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)，保持充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)壓(ya)為(wei)(wei)4.20V。此時，充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)逐漸下降，當電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)下降至(zhi)設定充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)的(de)1/10時，充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)(dian)結(jie)束。

USB充電可能沒(mei)充滿(man)

    電(dian)(dian)腦(nao)的(de)(de)(de)USB輸出(chu)電(dian)(dian)壓為5V，一(yi)般都很(hen)精(jing)準，之(zhi)所以大家覺得(de)USB充不(bu)(bu)滿(man)，是(shi)因(yin)為USB輸出(chu)電(dian)(dian)流(liu)小，而(er)(er)充電(dian)(dian)的(de)(de)(de)最后階段(duan)，需要有(you)涓流(liu)充電(dian)(dian)。涓流(liu)充電(dian)(dian)是(shi)用(yong)來彌(mi)補電(dian)(dian)池(chi)(chi)在充滿(man)電(dian)(dian)后由于自放電(dian)(dian)而(er)(er)造(zao)成的(de)(de)(de)容(rong)量(liang)損失。電(dian)(dian)池(chi)(chi)在充滿(man)電(dian)(dian)后，由于自放電(dian)(dian)損失的(de)(de)(de)容(rong)量(liang)大約是(shi)標稱容(rong)量(liang)的(de)(de)(de)5%。理論上說涓流(liu)充電(dian)(dian)要在充電(dian)(dian)電(dian)(dian)流(liu)的(de)(de)(de)1/500級別，USB電(dian)(dian)流(liu)只有(you)500mA，涓流(liu)很(hen)小了(le)，所以這個(ge)過程很(hen)慢很(hen)慢，你(ni)等(deng)不(bu)(bu)及(ji)拔下來，5%就沒了(le)。

   用(yong)什(shen)么充(chong)，只有電流的區別

   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)(shi)用電腦USB，不都是(shi)(shi)那(nei)根線嘛，用什么充，只有充電電流的(de)(de)區(qu)別，都得捅手(shou)機(ji)的(de)(de)“屁股(gu)”，只要你用USB線充電，另一端(duan)是(shi)(shi)神馬，原理上都是(shi)(shi)一樣的(de)(de)，只是(shi)(shi)充得快慢問(wen)題。

   經(jing)測試，筆記本電(dian)(dian)(dian)腦USB口對手(shou)機充電(dian)(dian)(dian)，與座充對裸手(shou)機電(dian)(dian)(dian)池充電(dian)(dian)(dian)相比，充電(dian)(dian)(dian)電(dian)(dian)(dian)壓(ya)略(lve)高（5V:4.2V），充電(dian)(dian)(dian)電(dian)(dian)(dian)流略(lve)低（190mA:220mA），但換臺(tai)式機的USB口，充電(dian)(dian)(dian)電(dian)(dian)(dian)壓(ya)仍(reng)為5V，充電(dian)(dian)(dian)電(dian)(dian)(dian)流漲為230mA。

   兩種充(chong)電(dian)方式并無明顯不(bu)同，USB充(chong)電(dian)會漏電(dian)的(de)說法不(bu)正確(que)。