Mustang1994

I recently notice it's hard to keep a charge in my battery. When i took it to auto zone for a test the guy said my alternator and battery (new one) is good. I even went and changed the battery terminals and checked the water level in the battery, and made sure all connections are tightly connected. Any suggestions? I have a pic of my car on standing charge and driving charge.

This is when I'm at a red light charge...




This is normal driving conditions

AdderMk2

do you have underdrive pullies?

USMC1775

Looks fine to me

getshocked40KVolts

dose it sputter what do you have hooked up to it? ie sound system, under light etc etc

greenstreak9205

+1 on the under drive pullies. If you do, it looks normal

Mustang1994

I do have an under pullie and I dont have any extra things like a sound system or underlights just normal car with some bolt ons... yea never thought about the pully thing. But I bet alternator is giving a false reading and not charging battery well enough..

greenstreak9205

no, that's what an under drive pulley will do. it spins the alt slower therefore its output wont be as high. its normal so dont worry about it

FordMustangXBA

As long as it is fine while driving, I wouldn't worry about it. I have pullies, fan, and a system in my car so I had to go with a bigger alternator than the stocker.

Mustang1994

Then why am I not getting a charge, must be my alternator

AdderMk2

holy **** you are thick headed..

your charge drops at idle because of the underdrive pulleys. it slows the alternator to the point where it can no longer produce a charge. If you want the "problem" to go away, put stock pulleys back on.

but like we have said. that is NORMAL for a car with underdrive pulleys