I have a 1999 Ford F-250 started off with battery going dead so checked alternator and battery and found out the alternaor was done so put in a new one and that didnt fix the problem so then figured new battery so tried that and also problem not solve so theirs a brand new alternator from ford and new mastercraft battery anyone know what could be wrong.

 

Did you check your Maxi-Fuses under the hood?

 

Have you checked parasitic draw. It should be under 50mAmp once the modules fall asleep

 

I just changed the alternator on my 99 Ford F150 and there are 3 connections to the alternator from the battery. One is an eyelet with a stud and nut and that would be easy. The other is a plug that cannot be placed incorrectly but the 3rd is a single wire connector. Maybe it is not connected???

The voltage regulator is integrated into the alternator so that couldn't be the culprit.

If it is not the cable connections, it could be in the cables from the alternator to the battery. One could be broken.

 

charge the battery full.
measure the battery to be 12.8 volts
start the truck and measure the battery voltage to go up to 14 volts.
if it does, you battery is crap or you have a big electrical leak when motor is off.
if it dont charge 14 volts, then alternator is crap, or not connected.

 

have you cleaned your terminals so they are shiny and bright

 

Parasitic draw can be no higher than 50mAmp. As little as a few hundred mAmps will pull a fully charged batteries down in a few hours. If you've replaced the parts you say you have(some multiple times) you need to look for parasitic draw.