battery getting drained while driving

If I let the car fast idle with choke on get 14.7 volts at the battery and alternator.With car normal idle speed around 900-1000 rpm drops to 12.6. Both reading with both fans on that draw 48 amps for the pair.Nothing else in the circuit.no cut off switches ect.The belt is serpentine and is new and tight.wire from alt to starter has factory crimps. the crimp at starter to batt. is a crimp style that I did and may not be the best crimp.The battery cont. uses a factory crimp-so don't think that is problem.Will take new optima from Jeep Wednesday and swap it with the car and see what kind of charge Numbers I get with it.This is really frustrating. The car will die driving around.Last time died after long trip on freeway!Check the batt.-read 11.4 volts.Sure was lower,but the volts could have come up after the car sat for 2 hours.
thanks for all the input.