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This seem to be a random thing but I'll be driving and I'll notice that the voltage meter begins to drop. Where it is more noticeable is when I come to a full stop and have to turn my blinker on, the meter drops more and the blinker actually slows down. I've recently had the battery changed and had the alternator tested.

When I start out in the morning the charge is good but it seems to happen in the afternoons on my way back home with a short commute. It was really obvious this summer during 90+ degree days. When the a/c was running the meter would approach the red area and I'd have to turn the a/c off.

Any ideas on where to begin?

Most people with your symptoms will find the problem in one of two places:

1. Battery cables themselves. Hidden corrosion UNDER the insulation of the cable itself. The only way to find it is to remove the boots from the cable ends and carefully trim back about 1/4" of insulation to expose the cable. If you see corrosion, replace the cables. A poor ground may also cause it, trace ALL black wires coming from the negative battery connection to where they ground on the vehicle, clean them and the mounting surface, and re-mount.

2. Ground busses underneath the front door sill plates. These connections ground most of the functions including the gauge, turn signals, etc. Remove the two front sill plates, dig under the carpet, and find the rectangular taped up thingy. Cut it open. Pull out the metal grounding lug and see if there's corrosion. If there is, clean it as well as you can, apply dielectric grease, and reassemble.

With your symptoms I would go #1 first. Where did you have your alternator tested? Does the problem only occur when the car is warmed up or has been driven for a specific amount of time or distance?

I am also having this issue. The symptoms you describe are right on. One person suggested to me that I might have a bad belt, causing slippage...thus a drop in volts. After replacing the belt the issue still remains.

I had my alternator tested at Auto Zone while it was still on the vehicle. For me, the problem is constant; doesn't matter how long or far I've driven. Its a problem from the time I start it, to the time I shut it off.

My post above applies to you as well. Start there and let us know what you find. These problems are more common when the weather turns wetter.

Now that the weather is getting colder here in Missouri, I have noticed that right at startup, the voltage drop isn't happening. After the engine warms up a little the voltage begins jumping around.

I will check the cables and let you know what I find.

If the cables check out, go back to the alternator. Try to determine if it only fails after it gets to a certain operating temperature. This is something a bench test can't really prove, and never trust Autozone's testers or the ability or knowledge of their employees.

jerrymacdaddy wrote: It was really obvious this summer during 90+ degree days. When the a/c was running the meter would approach the red area and I'd have to turn the a/c off.

Any ideas on where to begin?

Autozone tests your alternator with the hood open (or if carried in, at room temp) so the test temp is somewhat cooler than the underhood temp on a hot day, which can easily hit 150 degrees.

Clean the cables first. If that doesn't work, replace the alternator. I'd say there's a 95% chance that one or the other (probably the alternator) will cure what ails it.

I had the same problem.. as a matter of fact ive had a lot of issues with my charging system. Does the car stall ever?

Same problem here in NY, mainly since the weathers been cooler and wetter. I noticed that recently ive had water sitting in my battery compartment, which i think is coming from the trunk. Also the sunroof leaks on my car so its getting the front floor wet too

So it seems that options #1 &#2 could be a possibility for me.