Flickering Battery Light

[T0M3K]

Today morning I was greeted by another problem. This time the battery light flickers on me when engine is running, when stationary it blinked more frequently till I got solid red. When driving, flickering is less frequent. Last night it was working perfectly and except for low-oil light there is no indication or anything wrong.

[T0M3K]

So I've been doing some "troubleshooting" if you may say.
I used VAG COM on engine module, and was reading group 04 for voltage.
At rest, the voltage reads in 12.04 range which I think is not that bad (as I remeber cell should be 1.6V, so ideal ~12.8V), when the car is cranked, I get flashing Bat Light and it now continues to be solid, till I tap RPMs, then it flashes. I started logging and at first it starts in mid to high 13Volt range till it reaches around 14.07 I want to rule out possible problems, so far I am aware of only two major components, alternator and battery (btw, it's optima redtop). What else could trigger bat light?

[T0M3K]

Anybody?

[diagnosticator]

Anybody?

Any progress with this? If not, have the alternator load tested. The voltage regulator may be bad, or there is one or more bad rectifier diodes in the alternator output section.

[bavaria75]

I get the battery light sometimes (1 per week) when starting the car. Just the first 20-30 sec than it goes away. When I read the Vagcom I cmae back with the smae code "voltage low" or so. Guess no big deal, might be the battery is fading and towards the end of its life. I assume the computer measures the voltage of the battery and let you know if it is below a certain trashhold. No big deal to me until the car want start one cold morning here in CA.

[T0M3K]

I'm going to take voltmeter again and start some more "troubleshooting", here are related two pages from the manual, the "light" circuit looks simple enough.
I would think bad diode in rectifier would result in undervoltage, but my diode knowledge is quite limited. I will go to autozone and find out

[T0M3K]

Small update, Autozone are idiots
they told me to bring alternator and battery to the shop so they can test it. No thanks.
Checked again, same multimeter, battery is 15.0V, charges up to 16.9V. Checked my friends new Honda CRV, his battery is also 15V but charges at 17V. I looked at the circuit, maybe it is a problem with the sender

[n7plus1]

any update on this...mine flashed under normal driving for a split second today and hadn't flashed again the rest of the way home...

[T0M3K]

I talked to some people and they said, since it acts normal on the battery side, it is probably cut or damaged wire or bad sender.

[T0M3K]

It ended up to be a cut control wire from alternator, place that did my oil change put it back for me, now no problem