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)網電(dian)(dian)壓(ya)(ya)(ya)過(guo)(guo)低(di)(di)(di)。雖然充電(dian)(dian)器(qi)在低(di)(di)(di)玉下(xia)仍然可(ke)(ke)以輸(shu)出額定的(de)(de)充咆電(dian)(dian)壓(ya)(ya)(ya)，但當電(dian)(dian)網電(dian)(dian)壓(ya)(ya)(ya)低(di)(di)(di)于(yu)充電(dian)(dian)器(qi)的(de)(de)最低(di)(di)(di)電(dian)(dian)壓(ya)(ya)(ya)限定值(zhi)(zhi)時(shi)，也會(hui)使輸(shu)出電(dian)(dian)壓(ya)(ya)(ya)過(guo)(guo)低(di)(di)(di)。　維(wei)修方法∶首先用(yong)萬用(yong)表檢查—下(xia)高壓(ya)(ya)(ya)直流(liu)濾(lv)波電(dian)(dian)容是(shi)(shi)否(fou)(fou)(fou)變(bian)質、容量(liang)是(shi)(shi)否(fou)(fou)(fou)下(xia)降、能(neng)否(fou)(fou)(fou)正常(chang)充放電(dian)(dian)。如無(wu)以上(shang)問題，則測(ce)量(liang)一(yi)下(xia)開關(guan)功(gong)率管的(de)(de)電(dian)(dian)極的(de)(de)限流(liu)電(dian)(dian)阻以及源(yuan)(yuan)極的(de)(de)過(guo)(guo)流(liu)保(bao)護殮測(ce)電(dian)(dian)阻是(shi)(shi)否(fou)(fou)(fou)變(bian)值(zhi)(zhi)、變(bian)質或開焊、接觸不良。若(ruo)無(wu)問題，再檢查—下(xia)高頻變(bian)壓(ya)(ya)(ya)器(qi)的(de)(de)鐵(tie)芯是(shi)(shi)否(fou)(fou)(fou)完好無(wu)損。除(chu)此z外還有可(ke)(ke)能(neng)就是(shi)(shi)輸(shu)出濾(lv)波電(dian)(dian)容容量(liang)降低(di)(di)(di)，或開焊、虛(xu)接;電(dian)(dian)源(yuan)(yuan)輸(shu)出限流(liu)電(dian)(dian)阻變(bian)值(zhi)(zhi)或虛(xu)接;電(dian)(dian)源(yuan)(yuan)輸(shu)出線虛(xu)接等困素都不要放過(guo)(guo)，都應仔細檢查，確保(bao)萬無(wu)—失。