Going under-voltage when stopped
Thread Starter
TECH Regular
Joined: Mar 2009
Posts: 420
Likes: 0
From: Ricerville
Going under-voltage when stopped My Formula (mods in sig) keeps going under-voltage when it is at a stop, particularly with the A/C on. It keeps flirting with the top of the yellow zone and has actually gone into the yellow zone and sat there for an extended period of time. When I give it some throttle, it jumps back up, but it just sits at 13 volts all the time, even at cruising speed. Does this sound like a battery or an alternator issue?
Joined: Aug 2007
Posts: 24,241
Likes: 89
From: Turnin' Wrenches Infractions: 005
The problem is, you are taxing your cars electrical system. AC turned up and alt power output drops when they get hot. So hot weather and ac running put a heavy load on the charging system. Bottom line is this: Is your battery nice and hot when you go to crank your car up? Does it turn the starter over good? If it does, then your charging system is doing its job. Heat also takes a toll on batterys. So the summer will reveal some things you didnt realize during the cooler months.
check to see that the exciter wire going to the alternator is okay - thin wire going to the top of it. If it is kinked or damaged (esp hard to see at the connector), then your alternator will have reduced output. Happened to my friend....
I have a 1000 watt amp, 12" woofer with Matts all around and an under drive pulley on my 427ci.
I have a PepBoys OEM alternator. I can have my headlights on bright, A/C blasting on high, and the stereo hitting hard..........and the volts don't budge at all.
So you have a problem with your alternator or battery.....its not the amount of electrical items you have going at one time. Stock alternator is plenty to support everything you have perfectly.
It takes 15 minutes to change an alternator. Just don't break the little tiny excitor wire plugged into the top of the alternator while taking it out. Unplug that sucker first, before doing anything.
.
I have a PepBoys OEM alternator. I can have my headlights on bright, A/C blasting on high, and the stereo hitting hard..........and the volts don't budge at all.
So you have a problem with your alternator or battery.....its not the amount of electrical items you have going at one time. Stock alternator is plenty to support everything you have perfectly.
It takes 15 minutes to change an alternator. Just don't break the little tiny excitor wire plugged into the top of the alternator while taking it out. Unplug that sucker first, before doing anything.
.
