in the past on 2 cars when battery light came on during the rain it was the alternater. that being said you could check and clean all battery terminals, etc, check the battery.
2004 Ext Cab, 4WD, 4.0, Auto, 146k. (4.0 engine is out of a 2009 Ranger w/96k) ( as of 3/10/2016)
2004 Ranger, Ext Cab, 2WD, 3.0, 5 speed , 4WABS, crank windows, no cruise, Edge 116k.(6/5,2014) (SOLD).
1999 Ford Ranger, Reg Cab, 2.5, 5 speed, 2WD, no AC, 150k (SOLD).