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)壓過(guo)低(di)。雖然充(chong)電(dian)(dian)器(qi)(qi)(qi)在低(di)玉下(xia)(xia)仍然可(ke)(ke)以(yi)輸(shu)出(chu)額定(ding)的充(chong)咆電(dian)(dian)壓，但(dan)當電(dian)(dian)網電(dian)(dian)壓低(di)于(yu)充(chong)電(dian)(dian)器(qi)(qi)(qi)的最低(di)電(dian)(dian)壓限定(ding)值時(shi)，也會使(shi)輸(shu)出(chu)電(dian)(dian)壓過(guo)低(di)。　維修(xiu)方法∶首(shou)先用萬用表檢(jian)查(cha)—下(xia)(xia)高壓直(zhi)流(liu)濾(lv)(lv)波(bo)電(dian)(dian)容(rong)是(shi)否變(bian)(bian)(bian)質、容(rong)量是(shi)否下(xia)(xia)降、能否正常充(chong)放電(dian)(dian)。如(ru)無(wu)以(yi)上問(wen)題，則測量一(yi)下(xia)(xia)開(kai)關功率管的電(dian)(dian)極的限流(liu)電(dian)(dian)阻(zu)(zu)以(yi)及(ji)源極的過(guo)流(liu)保(bao)護殮測電(dian)(dian)阻(zu)(zu)是(shi)否變(bian)(bian)(bian)值、變(bian)(bian)(bian)質或(huo)開(kai)焊、接觸不良(liang)。若無(wu)問(wen)題，再檢(jian)查(cha)—下(xia)(xia)高頻(pin)變(bian)(bian)(bian)壓器(qi)(qi)(qi)的鐵芯是(shi)否完好無(wu)損。除此(ci)z外還有可(ke)(ke)能就是(shi)輸(shu)出(chu)濾(lv)(lv)波(bo)電(dian)(dian)容(rong)容(rong)量降低(di)，或(huo)開(kai)焊、虛接;電(dian)(dian)源輸(shu)出(chu)限流(liu)電(dian)(dian)阻(zu)(zu)變(bian)(bian)(bian)值或(huo)虛接;電(dian)(dian)源輸(shu)出(chu)線虛接等困(kun)素都不要放過(guo)，都應仔細(xi)檢(jian)查(cha)，確保(bao)萬無(wu)—失。