Charging system delay

[DanG]

When I start my cold 2002 2500HD LB7, there is a 30 second delay before the voltage increases from 11-12 to 14-15 approx. I this common? What the deal?:confused:

Thanks,
Dan

[DmaxMaverick]

It's normal. When you start cold, the glow plugs will cycle, even after the light goes out. In colder temps, the intake heater will draw more power yet. Cold startup diagnostics also draw more juice. It will also take a bit for the alternator to recover the batteries from a cranking cycle. The voltage is controlled by the PCM, unlike older models with a separate voltage regulator.

[Rabbler]

What exacty are cold startup diagnostics?

[DmaxMaverick]

What exacty are cold startup diagnostics?
The series of sensor checks the computer does when you start your engine. This happens every time you start it, but there are a lot more of them on a cold engine. Pretty standard since the onset of OBD, and mostly mandated by the EPA. All OBD vehicles have this.

[Rabbler]

So basically its just normal OBDII monitors. I don't see how that would increase current draw on cold start up. I thought there was maybe some special glowplug or IAH test you were referring to.