so strange 2006 Taurus

I posted here a few months ago about my car dying etc well the other day were had been out stopped o change drivers aind tried to.die I pulled out got.home which was about 5 miles it wouldn't restart so we jumped it and it ran we u hooked the battery it died so we were thinking alternator..We had it checked at 2 diff places it good and then we thought battery ...battery is good...We are stumped what else.could be it's a 2006 ford taurus se what could drain the battery? When e took it to be tested it was dead...but they charged it and tested it it was ok any ideas???

Follow the ground wire from the battery to the other end after first disconnecting from the battery. The other end when you find it, see if it is soaked in oil or if it is loose. Even if it isn't, it might be a good idea to disconnect, clean real well and then reconnect tightly. A bad, loose, dirty ground could lead to the battery not being recharged.