Battery dies with current load, ABS&SRS Lights up before car dies

I have a '91 190e 2.3. I installed a new ALT, Drive belt (with proper tension), new battery, terminal posts, and checked the cable ampage and continuity.

The car runs great until a Full load on the system occurs, i.e. radio, A/C or heater, headlights, and of course braking (brake lights).

After a while of driving, the car's SRS and ABS light will come on and the car will die. The battery is totally discharged.

Prior to this, the voltage(with car running) ranges between 13.8 to 14.4; with the accessories OFF. With accessories ON, voltage ranges between 13.1 to 13.7.

No power seats, no voltage drain.

Given the conditions above; is it possible that the Overvoltage Protection relay is @ fault.

Point me in the right direction...

Thanks in Advance, Ray