All disabling the alternator does is to prove what we already know.....that this is caused from action by the alternator. Doing so does NOT tell us where or what is actually wrong.
Pretty much what I said in my disclaimer. But it would rule out something else outside the charging system causing a cyclic drain and confirm it's in the alternator or regulator.
It's not likely to be outside the charging system, but stranger things happen.
The alternative is to test for ac voltage, and not everyone has the tools or ability to do so. If it is a diode, no number of ground straps or new regulators will fix it.
