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)網(wang)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)過低(di)。雖然充電(dian)(dian)(dian)(dian)器在低(di)玉(yu)下仍然可以(yi)輸(shu)出(chu)額定的(de)充咆電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)，但當(dang)電(dian)(dian)(dian)(dian)網(wang)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)低(di)于(yu)充電(dian)(dian)(dian)(dian)器的(de)最低(di)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)限(xian)定值(zhi)時，也會使輸(shu)出(chu)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)過低(di)。　維(wei)修(xiu)方(fang)法∶首先(xian)用萬用表(biao)檢(jian)查—下高壓(ya)(ya)(ya)直流濾波(bo)電(dian)(dian)(dian)(dian)容(rong)是否(fou)變(bian)質、容(rong)量是否(fou)下降(jiang)、能(neng)否(fou)正(zheng)常(chang)充放電(dian)(dian)(dian)(dian)。如(ru)無以(yi)上問題，則(ze)測(ce)量一下開(kai)關功率管的(de)電(dian)(dian)(dian)(dian)極的(de)限(xian)流電(dian)(dian)(dian)(dian)阻以(yi)及(ji)源(yuan)極的(de)過流保(bao)護殮測(ce)電(dian)(dian)(dian)(dian)阻是否(fou)變(bian)值(zhi)、變(bian)質或(huo)開(kai)焊、接(jie)觸不(bu)良(liang)。若(ruo)無問題，再檢(jian)查—下高頻變(bian)壓(ya)(ya)(ya)器的(de)鐵芯是否(fou)完好(hao)無損(sun)。除此z外還有可能(neng)就是輸(shu)出(chu)濾波(bo)電(dian)(dian)(dian)(dian)容(rong)容(rong)量降(jiang)低(di)，或(huo)開(kai)焊、虛(xu)(xu)接(jie);電(dian)(dian)(dian)(dian)源(yuan)輸(shu)出(chu)限(xian)流電(dian)(dian)(dian)(dian)阻變(bian)值(zhi)或(huo)虛(xu)(xu)接(jie);電(dian)(dian)(dian)(dian)源(yuan)輸(shu)出(chu)線虛(xu)(xu)接(jie)等困(kun)素都不(bu)要放過，都應仔(zi)細檢(jian)查，確保(bao)萬無—失。