Weird electrical issue
I'm having a weird electrical issue on my 97 f250 powerstroke.
It starts and runs fine. When the truck first starts the electrical gauge moves to about 8 volts, sits there for about a minute and then jumps up to normal. During this time any electrical components in the cab will be dim(lights) or slow (heater fan). When the gauge goes to normal everything seems fine. Sometimes the batter light will flicker while the gauge is at 8 volts.
I've replaced the batteries because they were getting old and I've tested/replaced the alternator. What else could be problem? It runs fine other than this. Also, when the truck is warm it seems to skip the charging at 8 volts phase.