One problem related to battery dead has been reported for the 1998 Ford Expedition. The most recently reported issues are listed below.
My 1998 Ford Expedition XLT has the leaking windshield problem, which has led to misdiagnosis by the dealer and by independent mechanics. The lights, fans, and switches randomly turn on and off, the power windows work intermittently, the blower fan and radio stays on, and the battery has gone dead three times. Today is the most recent occurrence of the problem, and I found it as noted in an online forum. Ford is/has been aware of the problem, yet will only fix it if the car has less than 75,000 miles on the odometer, which works intermittently as well. Apparently the repair will run in excess of $1,000, even though Ford has multiple reported cases of the same problem.