请大家帮我分析一下充电器会闪灯的问题

48V2.5A的电动车充电器,充电过程中如先拔下充电插头,充电器工作就不稳定了,红灯和绿灯一起闪,(电源指示灯和充电指示灯)电压在39V左右跳动,插上充电插头又可正常充电,但充满后充电指示灯红绿交替闪烁,(红灯表示正在充电,绿灯表示己充满)请大家帮我看看吧,先谢过了,附图纸,500) {this.resized=true; this.width=500; this.alt='这是一张缩略图，点击可放大。\n按住CTRL，滚动鼠标滚轮可自由缩放';this.style.cursor='hand'}" onclick="if(!this.resized) {return true;} else {window.open('http://u.dianyuan.com/bbs/u/62/2046591203226029.gif');}" onmousewheel="return imgzoom(this);">这张好象不太清楚,我找了类似的图纸请大家帮帮忙,看后请留话,谢谢了,500) {this.resized=true; this.width=500; this.alt='这是一张缩略图，点击可放大。\n按住CTRL，滚动鼠标滚轮可自由缩放';this.style.cursor='hand'}" onclick="if(!this.resized) {return true;} else {window.open('http://u.dianyuan.com/bbs/u/62/2046591203226154.jpg?x-oss-process=image/watermark,g_center,image_YXJ0aWNsZS9wdWJsaWMvd2F0ZXJtYXJrLnBuZz94LW9zcy1wcm9jZXNzPWltYWdlL3Jlc2l6ZSxQXzQwCg,t_20');}" onmousewheel="return imgzoom(this);">