Battery Drain

[revkev77]

I have a 1995 F250 4WD with a 91 7.3 IDI, I have two brand new NAPA batteries , and new battery cables. I replaced the voltage regulator, and starting relay, the one that goes to the glow plugs. NAPA checked the 60 amp alternator and said it was good after it passed three test.
Now the problem when the truck sits for more than 10 hours the batteries are so low they will not start the truck. I don't have any extra accessories and the radio is off, what could be draining the batteries? I'm thinking maybe its the control relay cycling for the glowplugs when the temp drops, but don't think it works with the ignition key turned off. Any ideas where or what to check?

 

[sassyrel]

take the hot wire off the alt--and set it aside for the night--if batts are ok--youve got a bad diode in the alt--theyll charge ok--but a diode is a one way elec valve--and they can short open--to grd--orrrrrrr--they short in such a way--that the current reverses when shut off--have put diode plates in more than one ford

 

[jauguston]

Take the positive cable off of both batteries - if you have a test meter with a 10a scale hook it between one cable and one battery and see if you have something drawing current. If you don't have a meter with that much draw you will probably see it by momentarily touching one cable to one post and look for a spark when they touch. It helps if it is semi-dark to see the spark. If you have a draw for starters pull all the fuses you can find and hopefully one of them will kill the draw. That should narrow down where the problem is.

Good luck - those things can be elusive.

Jim

 

[Compu Doc]

One other thing you could do is feel if the alternator is warm after about 2-3 hours after shutting down. If it is then have the alternator replaced or rebuilt.

It happened to mine although the alternator was still charging ok.

 

[Mr_Roboto]

Also a good computerized battery / charging tester will detect the voltage "ripple" caused by a shorted diode.

 

[argve]

using an amp meter will find the source of your sneak circuit. In some cases the sneak comes from before the fuse block (as it was in my case). Make sure that you check all wires.