Voltage problem..? 1998 Mustang GT

When I accelerate at normal speed my voltage meter drops slightly. But when I “unleash it” and take off it really drops resulting in my battery light coming on also. Once I get up to speed in both scenarios it goes back to a norm. I have replaced the battery,belt, and tensioner(per past advice,thank you)but why would this still be happening? Oh and I checked the alternator, told it was ok…? Is this normal?

How does the voltmeter act if you just slowly rev up the engine in neutral? Does the car have to be in motion for this to happen?

No the car doesn’t need to be in motion to drop the voltage. It can happen with it sitting still, and mashing the accelerator pedal hard.

Did the test involve revving the engine while observing the test voltage? Probably not. I volt for an alternator with worn out brushes.

I second that vote (or volt). The brushes are flying away from the slip-rings as the rotation speed increases.

you’re right I didn’t but I will. Thanks. I’ll let you know how it goes!

That was the problem. Checked it under load at my local parts store and it confirmed I need a new alternator. Thanks “hellokit” and “tardis”!