slow blinkers(1blink per 5 sec) turn headlights on, radio goes off

I think all these problems are related but don't know. 85 full size bronco, 302 throttle-body, 4 speed,4x. Everything worked then It sat for 1 month, started it up, and noticed blinkers blink really slow, about 1 per 5 sec. also when headlights turned on, radio goes off. The dash shows no battery charge but does show drop when acc. turned on. I changed the alternator, voltage reg. and battery, but no change. I have been told it could be the headlight switch, relays, and everything else. I don't see how sitting 1 month can change this, but it has. Please help when possible, thank you