Car electrics freaking out

When driving, everything is fine, for like 5 seconds, then my battery light and emergency brake light flicker on and off, then after driving stay on and my airbag light flikers on and off. Then, my speedometer flips back and forth until it hits 0 and stays there. My fuel gauge also falls to E. I noticed my windshield wipers run real slow and it seemed to worsen when I pushed the brakes in (I figure because it causes lights to come on - the car using more electricity). It got a litle better, for a minute, when I turned my headlights and radio compltely off. I replaced the battery two days ago and everything was fine until after about 40 cumulative minutes of driving. What is going on with this!?