low voltage

[PowerSTOKED_Bryan]

hey guys.

my girl friend just bought an early 99 f250, 150,000 miles with a hand shaker....good price....the truck was sitting for a few months and our friend needed to unload it...he charged the batteries and dropped it off to her house...we bombed around the block a couple times untill she got it registered. ran great with no starting issues...hopped into the truck on friday and it wouldnt crank over fast enough to start up...so i hooked up the charger to the passenger battery just to give it a little help to crank over. got it going and drove it home. left it running for a bit....drove it a little saturday evening all was good, sunday morning it was good untill the ride home....i noticed the lights were dimming...the radio lights were flashing, and the windows wouldnt work. i figured the alternator wasnt charging and needed to be replaced...i got home from work today and tried to close the windows and when i opened the door i noticed the dome light was very bright. i thought that was strange...turned the key to the on posistion and noticed the voltage went from like 12 volts to like 9 in a split second...the windows wouldnt go up with the key in the on posistion but when turned back into the off posistion they went up. do i just have a bad battery on my hands or is it something else? i just thought it was wierd to have 12-13 volts and then it just drop wicked quick...maybe its because of the load of the glow plugs??? any input is appreciated.

[Johnsabine2003]

Probably an open cell in one of the batteries. Tests fine until you put a load on it.


Typed with my thumbs from my Autoguide app.

[PowerSTOKED_Bryan]

that would make the lights dim while driving too? it was wierd....it was fine for the few times we drove it prior but on the last drive home it had the problems..

[model-t-man]

Had simular starting problems. The 2 Ford batteries would not pass the load test and had to be replaced. Also, the alt which should have a rating of 130A was only capable of 44A. After all was replaced, the problem was resolved.

[PowerSTOKED_Bryan]

thanks for the input guys. i ended up slapping two new napa gold batteries and an alternator in it...she drove it home and all seems well so far...