turn on delay & problems that it can cause

i have a question involving my 07. i have factory twin alternators also . when i start up theres about a 30-45 second delay before the alternators tun on ( or the primary to the best of my knowlage) during this " delay " the truck idles and voltage rests at around 11.8. also during this time my FICM voltage is low low .. ive seen it as low as 41.5v eekkkk . ive read that this is caused by the glow plugs staying active causing the voltage to drop , however i can actually hear the motor bog down ( indicating the alts kicking on putting a load on the motor) and then voltage slowly rises . takes about 2 minutes for the FICM to reach 48.5 . i just cant believe the voltage is due to glow plugs. it never did this not once last winter . so heres my questions . .

is my primary alt shot , and the truck just takes a minute or so to realize theres no output from the primary , thus turning on the secondary?
and am i going to f**k up my FICM seeing that low of voltage every time i start the truck?