Hello I need help! I have a severe battery drain and I hooked up my volt meter, set it to DCA 10A, disconnected neg terminal and put volt meter between neg terminal and neg cable and it says 5.3A!!! I removed fused from drivers side and under hood the only thing that drops it is the 100A alternator fuse!! I replaced the alternator 2 days ago since the batt was tested and the other alternator had a noisy bearing and vehicle was doing same thing. So batt tests good and alternator puts out 14.38V to batt terminals. So why is it drawing and am I reading correctly? Any help would be appreciated

truck batt will die if I roll windows down and up with ignition off. Truck always has barely enough to start

 

Could be defective alternator but sounds like you got parasitic draw, since you say was dying before new alt, anything aftermarket installed?

 

Agree on the aftermarket gizmo tie in. You can take wires off the back of the alternator but leave it installed in the truck. If amp drain remains / goes away with 100 amp fuse link removal you have a very short distance to check for a "rub" or cut in the insulation. It is the Brown wire from fuse box to alternator. Could also be crud inside the fuse box. Good electrical connections are clean, not covered with corrosion, etc.

I would have also guess starter solenoid until you said the 100 amp fuse removes it. The starter solenoid has a constant connection on one side to the positive battery post.

 

I disconnected all cables on back of the alternator and the draw remains. ALL aftermarket equipment is disconnected. Also I have the red wire from meter on neg batt terminal and black wire on neg batt cable. Not sure if its reversed or I have a positive cable in the truck grounding out giving me this reading. When I take all fusible links out and all fuses the draw goes up to 14 Amps so it says?! not sure how to proceed since no fuses solve draw except 100A. Volt meter set to DCA 10A and hot lead switched to 10A section of meter

I did remove, open and check fusebox but the 100A section os very straight forward with hot going in and out.

All connections are bright and secure

Thank You!
John

 

Remove meter from circuit.

Leave battery cable off.

Leave alternator wires off.

Remove 100 amp fuse link.

Read for ohms between frame or engine block and the brown wire that is no longer connected to alternator. Or physically search this wire. Or run a new piece even temporary. Wire could be pinched, skinned, rubbed, melted, etc. The connection will make parasitic drain vary. Wire is not too long, but does carry maybe 100 amps under full charge from stock alternator. It won't be as big as battery cable.

 

FIXED. Positive cable had corrosion half way to starter, corrosion on 100A supply to fuse box and corrosion in negative cable about two inches. Went to auto store and purchased see through 4awg cable and replaced the cables and reground metal ground on chassis. Starts like a champ and wasnt that expensive