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)網電(dian)(dian)(dian)壓(ya)過低(di)(di)(di)。雖然充(chong)電(dian)(dian)(dian)器(qi)在低(di)(di)(di)玉(yu)下仍然可以輸(shu)出(chu)額定(ding)的(de)(de)充(chong)咆(pao)電(dian)(dian)(dian)壓(ya)，但(dan)當電(dian)(dian)(dian)網電(dian)(dian)(dian)壓(ya)低(di)(di)(di)于充(chong)電(dian)(dian)(dian)器(qi)的(de)(de)最低(di)(di)(di)電(dian)(dian)(dian)壓(ya)限定(ding)值時，也會(hui)使(shi)輸(shu)出(chu)電(dian)(dian)(dian)壓(ya)過低(di)(di)(di)。　維修方(fang)法∶首(shou)先用(yong)萬(wan)用(yong)表檢查—下高壓(ya)直流濾(lv)波電(dian)(dian)(dian)容是否(fou)(fou)(fou)(fou)變質、容量(liang)是否(fou)(fou)(fou)(fou)下降、能否(fou)(fou)(fou)(fou)正常充(chong)放電(dian)(dian)(dian)。如(ru)無(wu)以上(shang)問題，則測(ce)量(liang)一下開(kai)關功率管(guan)的(de)(de)電(dian)(dian)(dian)極(ji)(ji)的(de)(de)限流電(dian)(dian)(dian)阻(zu)(zu)以及源極(ji)(ji)的(de)(de)過流保(bao)(bao)護(hu)殮測(ce)電(dian)(dian)(dian)阻(zu)(zu)是否(fou)(fou)(fou)(fou)變值、變質或開(kai)焊、接觸不(bu)良(liang)。若(ruo)無(wu)問題，再檢查—下高頻變壓(ya)器(qi)的(de)(de)鐵(tie)芯是否(fou)(fou)(fou)(fou)完(wan)好無(wu)損。除(chu)此z外還有可能就是輸(shu)出(chu)濾(lv)波電(dian)(dian)(dian)容容量(liang)降低(di)(di)(di)，或開(kai)焊、虛接;電(dian)(dian)(dian)源輸(shu)出(chu)限流電(dian)(dian)(dian)阻(zu)(zu)變值或虛接;電(dian)(dian)(dian)源輸(shu)出(chu)線虛接等困素都不(bu)要放過，都應仔細檢查，確(que)保(bao)(bao)萬(wan)無(wu)—失(shi)。