im glad someone has pointed out that the operation ive been seeing is not normal, or i would have never know. i really appreciate the info.
now, next question, i noticed leaving work this morning, key on, FICM 49V, battery volt i dont remember, truck fired right up after glow plugs heated, voltage never dropped. as soon as the truck started, it was 48.5, 46, 44, 40, etc, all the way to 28v
...then after about a minute, to a minute and a half idle, i was back up around 38v, and about half way home (11 mile drive) i was at 49v. truck never acted weird or did anything funny which is what stumps me. im going to pull the FICM in the morning after work and see if i can do the fix myself, since i have the tools and knowledge (and the write up).
i saw the battery voltage drop to 11.6-11.8 right after start, and stayed around the mid 12's until i actually started driving. hot idle in the driveway was only fluctuating between 13 and 13.3 volts. recommendations on an alternator? i think the batteries are only a year or two old. i'll double check that though. what should i go with alternator wise? i may as well go ahead and do it. i saw factory was 110amp i believe. so should i go with the 140amp replacement for the extra power, seeing as ive read the factory just isnt enough.