sounds to me like your battery is being drained like you have a small draw somewhere. small enough to when you drive around and stuff its not enough to notice but when it sits over night its enough to drain it down. ive seen this before because everything will still test good because nothing is actually bad but theres a draw to weaken things up. idk if this helps at all but good luck.
97 TJ-3" BDS,1" BL,1" MML,3/4" front spacer,superwinch,33x12.5" BFG At,15x10 soft 8's