The "Dead Batteries" part is what's REALLY SCARY!
Think about it...

Only Two causes come to mind:

The EMP Generator is one
(Ain't nobody 'Cept maybe Somebody's [?] Government riding around with one of those...
No, Don't EVEN go the George Noory route,Aliens don't want anything in your car!)

OR (And I'm not even sure this is possible Electrically/Physically/RF)

Some kind of device that "Excersises" some control over ONE large consumer
,or MANY small consumers So that the Batteries are Drawn Down to "Dead".
Mayhaps, a "Rolling Code" breaker box that wears out the Batteries,trying to
open the Remote Door Unlock Functions of the Vehicles involved?

I.E. : "Lock, Unlock, Lock, Unlock, Etc., Etc.,Etc. Ad Infinitum until Battery's
Dead ?

Only reason I got started here...Remember all the trouble with unshielded
control cables in the Fly By Wire system on the Apaches Originally?
Some one in Utah would make a Cellphone call and an Apache would fall out of the Sky in North Carolina?

Well,none of the Electronics on these cars are shielded...In Fact the Remote
Antenna is a perfect "Back Door" to wreak havoc on the electrics/electronics.

bluestripe67,
LOOK @ your zip code...

The Guys and Gals at NSA testing out some new equipment in y'alls neighborhood?

'Just how far Geographically are Y'all from Embassy Row?

PRC ops screwing with U.S. Citizenry...
嗨，它在他們的汽車上工作。
以及通用製作他們的箱 ...

Uncle Vladimir's Comrades using Y'all as a Test bed for Tank Disablement...
Эй, Это воздействует на их автомобили.
И GM Делает их Резервуары...

Best possible causation: Someone @ "OnStar" was bored
(And all the Vehicles involved were made by GM)

Streknik and Tinypanzer are both correct.

I've got an remote RF device that disables/disconnects the Battery.
(And it has it's own Tiny 12V power source.)
[And it's not anywhere near the Battery]
I'm LOOKING @ it as another Weak Link, Now.

__________________
'84 300SD sold
124.128