Battery Drain Down Problems

[tigertom61]

I have a 99 F-250 with some sort of drain on the batteries. I first replaced the alternator 2 times and new batteries. I still have some sort of drain on the batteries even after a full charge and the new alternators?? What is a good set of diagnostic steps to take to help with the troubleshooting??? Not a bad problem for 409K on original motor and trannie, but it sure would assist with the use of the vehicle

[tigertom61]

Hey guys, I thought it was the starter solenoid and replaced....no such luck. I started the fuse elimination and found it to be, so I thought, was the 20amp that runs the radio. It made my test light go out, but still had a drain on the system? Still at a stand still at this point, as the process of elimination goes on.

[2005F250]

Could it be related to the ignition? Are there any aftermarket accesories added to the vehicle like amps, electric steps, lights, fuel pump for an in-bed fuel tank, air compressor?