Battery still being drained

[Bumpside70]

Hey everyone. I'm still having some problems with my 70 F250. This has been going on since September . Something keeps draining my battery after driving for 3 or 4 days in a row. I replaced the alternator in November, and bought a new battery last week. After installing the new battery last Tuesday, it was totally drained by Friday night. Do you think it has something to do with the wiring harness going bad? Thanks for any help you can give me. Oh I forgot to mention the voltage regulator has also been replaced.

[Bumpside70]

Thanks for the info Thunderfoot. Its draining after driving 3 or 4 days. It does fine while sitting. I've never owned a car or truck that has done something like this. Its got me stumped big time.

[Thunderfoot]

That sounds like it is not charging alright… These old trucks don’t use much voltage driving around during the day, so they will go about 3-4 days on a good battery and charge.
I just had the same thing with mine a couple of weeks ago as my alternator died and didn’t know it (as my amp gauge doesn’t work) I trouble shot it down to the alternator by jumping the field and checking the battery voltage with a volt meter, it didn’t change so I knew it was the alternator. Pulled the dirty/ugly one out of my other truck and put it on, all fixed. Now I’m in the process of installing a Voltage gauge.
Best thing to do is get one of those meters then you can trouble shot it easy and even be able to check some of the wires for opens, like the fusible link.

[willowbilly3]

Those alternators do fail but not near as often as the voltage regulator. You can full field the alternator to test for output by unplugging the regulator and jumping across the first and third wires with a jumper. This makes the alternator go to full tilt boogey so DO NOT rev the engine or you might fry something, idle only. You will of course need the voltmeter to do this test.
Now that bad part, if you need a new regulator, only Ford made good ones so you need to find a Motorcraft or Autolite. Even a used one from a junk car is better than anything you can buy over the counter. Any regulator you buy at a parts house is bound to bring you grief.

I just re-read that you already changed the regulator. I'd give odds it's not working right if it isn't a Ford bran.