About 4 months ago i replaced my alternator because the last one had died on me. I choose to go with an 80 amp this more for a little more power for the future. The new alternator actually seems weaker than the old one did before it died. For example, at idle at a light or anywhere really, if i have mylights on and heater going the volt gage drops right to the 'N'. I i use any other accesory such as my power windows it drops even below that but, my voltage warning light doesnt come on. What could be the cause of this?