power drains batteries dead in 10 min or less

[uponthehorzion]

Hi
I have a 1998 ford expedition which has suddenly developed an extremely high amp current draw/short that suddenly drains the battery in a matter of minutes.
I tried two batteries to eliminate the battery, also tried disconnecting the air ride compressor by pulling the 50 amp fuse in the power distribution box and started it and the fully charged battery drained the battery to a dead stall out without even a dome light in about 7 mins.
It's losing so much current so fast I expected to smell smoke or find a melted or at least discolored #8 or bigger power supply wire. I can't understand where that much current could draw off that quickly without being more obvious like the starter wire arcing off the exhaust pipe or manifold.
Any ideas?
Thanks, Craig in Michigan aka uponthehorizon

 

[stamp11127]

Disconnect the battery 1st then the large red cable on the alternator followed by the starter cable on the starter solenoid. Reconnect the battery, a large spark will indicate a high current draw so the problem would be elsewhere. Also check the positive battery cable for a short to ground.

 

[uponthehorizon]

power drain, username error uponthehorizon, not "uponthehorzion"

Hi Stamp,

Thanks so much for the rapid reply!
I could not figure out why i could not reply till i noticed my spelling error in my username.

I followed your instructions, discovered bad or questionable "cooked" grounds, main to starter and loose and cooked frame ground. I meticulously cleaned and repaired all the grounds and also the power connections at the starter and of course battery and applied dielectric grease to all those connections.

Also, alternator was bad, perhaps a result of these poor ground's causing some intermittent current spikes.
Whenever their is a "mysterious" element to an electrical system the grounds are a highly suspect factor. In this instance i hold them responsible for the weird discharging and and big current draws at jump starting. (draw was so high at jump start i lost radio presets in jumper vehicle and as i mentioned the expedition stalled out in a min or two unless i fully charged the battery then reconnected to vehicle, that gave me 7-10 mins run time)

Expedition is up and running and starting like it never did before. Always was a slower cranking at start up.