Quote Originally Posted by oj88 View Post
Wires will always introduce a certain degree of voltage drops. Especially if there's a lot of current passing through it.

That is what's happening in your case. The cigarette lighter socket practically shares the same wire coming from the battery to power up all electrical and electronic accessories in your car. The more electrical load being used, the lower the voltage is across the +12V wire. In geek speak, that's Ohm's Law at work.

You typically get a more stable voltage when you get the reading directly off of the battery posts.
salamat sa lahat ng replies.....i was also thinking na mataas ang resistance offered by the wire. pati kasi sa ignition terminal lower by about 1 volt than batt voltage. but at least mas stable ang voltage readings sa ignition terminal kesa dun sa lighter socket. radio is also tapped to the same wire where lighter is tapped. bale inisplice ko lang voltmeter connection dun.

di rin dinaan sa baha. yung mobile undercarwash lang sa highway kadalasan pero may protective splash pad naman sa sides ng engine compartment. tsaka 1 year pa lang nung nagpalit ako alternator at carbon brushes.

nakakaantok pa naman magsphagetti (wiring). parating mababa ang ulo.