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)(ya)(ya)(ya)過低(di)(di)(di)。雖然充(chong)電(dian)(dian)(dian)器在(zai)低(di)(di)(di)玉(yu)下(xia)仍然可以輸(shu)(shu)出(chu)額定的充(chong)咆(pao)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)，但當電(dian)(dian)(dian)網電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)低(di)(di)(di)于充(chong)電(dian)(dian)(dian)器的最低(di)(di)(di)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)限(xian)定值(zhi)時，也會(hui)使(shi)輸(shu)(shu)出(chu)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)過低(di)(di)(di)。　維修(xiu)方法∶首先用(yong)萬用(yong)表檢查—下(xia)高壓(ya)(ya)(ya)(ya)直流(liu)濾波電(dian)(dian)(dian)容是否變質、容量(liang)是否下(xia)降、能(neng)(neng)否正(zheng)常充(chong)放電(dian)(dian)(dian)。如無(wu)以上問(wen)題，則測(ce)量(liang)一下(xia)開關功率管的電(dian)(dian)(dian)極的限(xian)流(liu)電(dian)(dian)(dian)阻以及(ji)源(yuan)極的過流(liu)保護殮(lian)測(ce)電(dian)(dian)(dian)阻是否變值(zhi)、變質或(huo)開焊、接(jie)觸不良(liang)。若無(wu)問(wen)題，再檢查—下(xia)高頻變壓(ya)(ya)(ya)(ya)器的鐵芯是否完(wan)好無(wu)損(sun)。除此z外(wai)還有可能(neng)(neng)就(jiu)是輸(shu)(shu)出(chu)濾波電(dian)(dian)(dian)容容量(liang)降低(di)(di)(di)，或(huo)開焊、虛(xu)接(jie);電(dian)(dian)(dian)源(yuan)輸(shu)(shu)出(chu)限(xian)流(liu)電(dian)(dian)(dian)阻變值(zhi)或(huo)虛(xu)接(jie);電(dian)(dian)(dian)源(yuan)輸(shu)(shu)出(chu)線虛(xu)接(jie)等(deng)困素(su)都(dou)(dou)不要放過，都(dou)(dou)應(ying)仔細檢查，確保萬無(wu)—失。