97 powerstroke battery light

[hurd]

hey guys i just bought a 97 250 around a month ago. ran like a top till this past weekend when the battery light came on. i installed a new alt and charge my old batteries. drove it that evening and all the lights went dim and gauges went crazy and it wouldnt hardly shift. charged the batteries AGAIN come to find out there dead. got two brand new batteries. took the alt back and got another new one just in case and the battery light is still on the batt gauge is just barely at the "n" in normal range. i noticed today that i have a wire that appears to be burnt or corroded really bad and has broke into going to the starter relay on the pass side behind battery. im new to the diesel world so im lost. any help would be greatly appreciated. im so frustrated with it at this point id just like to know where to start on it

[sooty4545]

First i would fix that burnt/corroded wire you were talking about, even if it doesn't help the battery charging problem it probably needs attention. If that does not fix the charging problem I would make sure the ground is good between the batteries and the alternator or just the battery ground in general. What is the voltage at the batteries with the engine running? 14 something volts and its charging, Having worked on many cars with charging problems I have learned that 8 out of 10 times it is corrosion or a bad ground somewhere. Good luck let me know what you find.