Voltage?

[wemtd]

Is 0.5v significant?

 

While trying to chase down an engine performance issue earlier this summer I hooked up my laptop and discovered my car voltage is averaging ~ 13.4v while running. It previously averaged ~14v (read from ECU, dash gauge is steady at 14v). Everything else seems to be ok, I replaced the alternator's voltage regulator (boring story) and polished my battery cables and still see the same voltage. Admittedly I've never paid this much attention to the voltage. Rear lights were changed to LED's last year and 3A 50Vpeak diodes were added to the indicator circuit (stock wiring used the inactive side as ground for the activated indicator light - too little resistance for LED's activates both sides simultaneously without a diode)

Standard disclaimer: [stock 2.0 duratec, haltech ECU, ITB's, coil on plug direct fire - stock injectors/packs, etc]

 

While statistically significant. Is this enough of a difference to be relevant to operation of the car? (I suspect a touchy ground somewhere)

 

V=IR is about all I remember...

 

 

p.

Edited July 30, 2018 by wemtd

[coffee break]

FWIW Is the belt in good condition with good tension? Also, some autopart stores will run alternators on a test bench to check output. Autozone?

[xcarguy]

A couple of thoughts:

 

Where’s in the electrical system is the volt meter getting its reading from?

Have you used a multimeter and taken a reading directly from the alternator?

[panamericano]

I've always thought 13.6 was right on, so you are not far off. Above points are good. If your laptop is reading off the ECU, maybe that causes a couple tenths drop. Some circuits have a built in resistance. Are you having any negative symptoms?