電動車充電器直流電壓輸出過低，根據維修經驗，除穩壓控制電路會引起輸出電壓過低外，還有以下幾點原因：
   （1）輸出電壓端整流三極莒、濾波電容失效，可以通過代換法進行判斷。
   （2）開關功率管的性能下降，導致開關管不能正常導通，使電源的內阻增加，帶負載能力下降。
   （3）開關功率管的源極通常接一個阻值很小但功率很大的電阻，作為過流吳護檢測電阻。該電阻的阻值—般在0.2～o.8ω。如該電阻變值或開焊、接觸不良也會造成輸出電壓過低。
   （4）高頻脈沖變壓器不良，不但造成輸出黽壓下降，還會造成開關功率管激勵不足從而屢損開關管。
   （5）高壓直流濾波電容不良，造成電源帶負載能力差。
   （6）電源輸出線接觸不良，有—定的接觸電阻，造成輸出電壓過低。
   （7）電(dian)(dian)(dian)(dian)(dian)網(wang)電(dian)(dian)(dian)(dian)(dian)壓過低(di)。雖然充電(dian)(dian)(dian)(dian)(dian)器(qi)在低(di)玉下仍然可以輸(shu)(shu)出(chu)額定(ding)(ding)的(de)(de)充咆電(dian)(dian)(dian)(dian)(dian)壓，但當電(dian)(dian)(dian)(dian)(dian)網(wang)電(dian)(dian)(dian)(dian)(dian)壓低(di)于充電(dian)(dian)(dian)(dian)(dian)器(qi)的(de)(de)最低(di)電(dian)(dian)(dian)(dian)(dian)壓限(xian)(xian)定(ding)(ding)值(zhi)時，也會使輸(shu)(shu)出(chu)電(dian)(dian)(dian)(dian)(dian)壓過低(di)。　維修方法∶首先用(yong)萬用(yong)表檢(jian)查(cha)—下高壓直流(liu)(liu)濾(lv)波(bo)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)是否變質(zhi)、容(rong)(rong)(rong)量是否下降、能(neng)否正常充放電(dian)(dian)(dian)(dian)(dian)。如無(wu)以上問(wen)題，則測量一(yi)下開關功率管(guan)的(de)(de)電(dian)(dian)(dian)(dian)(dian)極的(de)(de)限(xian)(xian)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)阻(zu)以及源極的(de)(de)過流(liu)(liu)保(bao)護殮測電(dian)(dian)(dian)(dian)(dian)阻(zu)是否變值(zhi)、變質(zhi)或(huo)開焊、接觸不良。若無(wu)問(wen)題，再檢(jian)查(cha)—下高頻變壓器(qi)的(de)(de)鐵(tie)芯是否完好(hao)無(wu)損。除此z外還有(you)可能(neng)就是輸(shu)(shu)出(chu)濾(lv)波(bo)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)容(rong)(rong)(rong)量降低(di)，或(huo)開焊、虛接;電(dian)(dian)(dian)(dian)(dian)源輸(shu)(shu)出(chu)限(xian)(xian)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)阻(zu)變值(zhi)或(huo)虛接;電(dian)(dian)(dian)(dian)(dian)源輸(shu)(shu)出(chu)線虛接等困素(su)都(dou)不要放過，都(dou)應仔細檢(jian)查(cha)，確保(bao)萬無(wu)—失。