回複：續：德國 VW golf 疑惑

地線接觸不良等於附加電阻。
結果：減少充電電流，降低電壓。

有可能是發電機的問題。 特別是碳刷摩損嚴重時。
建議：do a charge system test and voltage drop test.
pay attention to charging current.
pay attention to negative cable on the body end, how rusty is it.
pay attention to those wires at ignition switch. if I did not remember any thing wrong.
if you want to do a current draw test.
shut off the car turn everything off.
remove negative cable from battery.
connect a current meter (電流表）between battery post and the cable the cuurent should be less than 0.1 - 0.2 A. if no remote starter or security sys etc. on it.
if more than that take main fuse one by one and watch the current change. then take off sub- fuse. it takes a lot time.