2002 expedition 5.4 electrical problem.

Started engine as usual,no problems,drove several miles,went through small creek 3inches and hit far mud bank with a jolt due to ice and the uphill. Couple of minutes later noticed all gauges dead, and engine slightly coughing and minutes later engine quit. Towed home ,charge dead battery (which is brand new) and has clean terminals. Bought a new generator (altenator) and installed .Took test drive and generator was very,very hot to the touch and the charge indicator on dash pegged to top,then back to normal,several times.Measured 3 ohms from plus battery to plus cable,key off. When I took cable off of battery and measured battery I got 13.5v........help

The brand new altenator (not a rebuilt) was bad. I just would not accept that the first one putting out 19 v was bad. another alt. cured the problem. bernie