Lazy Morning Alternator????

[40grit]

2300 MIles,Seems every morning my alternator has a slight delay in it to get up to "normal" voltage. Truck starts great, no problem, but the guage intrigues me. It starts around 12V, waits for a little over a minute, then slowly move to a little over 14V. Doesn't seem to matter if I sit there and idle, rev it a little, or drive away. it acts the same way. This is all happening in the winter of Southern California ( it's a blustery 44*). so I'm wondering how it's going to react if I go someplace really cold.

p.s. GM needs to shoot who every designed the voltage gauge, the range doesn't match the numbers unless you use some weird division for the tick marks...wouldn't 1/2 volt per tick have been just fine?

[cabletech]

Nothing wrong with your alt. The intake heater stays on and draws more than the alt can put out. When the heater shuts off, the voltage goes up to normal.

[DieselMonk]

the only way in fixing that would be to install the 2nd alternator option. then you have plenty power all the time.

[jbplock]

FYI .. The following article in the members area includes a description of the improved intake heater on the LLY/LBZ's ...

http://www.thedieselpage.com/features/2006MY.htm

As cable tech pointed out the initial low voltage at cold startup is normal.

Anyone with dual alternators notice a difference in this behavior?

:)

[EdHale]

I have dual alternators and I see the same thing at idle. As soon as I add a few rpm's the voltage climbs up to the normal range, but it is still a little low for a minute or two. Ed

[40grit]

after the first minute, the voltage stays up above 14, even at idle. just kinda strange, not sure if it's done it before and I didn't notice or it's something the dealership will claim is "normal"...
thought I'd check it out with the guys here and see what most people say..thanks for the input..

[letsgo]

Another consideration is the volt meter in the truck is operated by a voltage sensitive resistance coil (not current) wraped around a bimetalic strip that bends when heated, moving the volt meter needle, Sooooo the colder it is the longer it takes to heat the bimetalic strip. Plus the thirty second time delay for the power transferto truck systems.

good luck

[40grit]

Huh, If it is a resistance thing, then it is current thru that item that would heat it up( voltage is merely a potential, no heat is generated until the current flow causes I2R losses...I would think they used something easier than that... a small voltage circuit is easy to find and works super fast...something like a D"arsonaval meter movement, no "heat up required", but I doubt they use an old fashioned meter movement, it's gotta be all computerized solid state circuitry..nothing to heat up prior to it working right...

I'm going to grab the DC ammeter from work and find out how much the air heater element draws...

[Idle_Chatter]

Don't forget you have glow plugs and an intake air heater that are cycling at startup. It's perfectly normal for the volts to be down during those cycles. I use it as an indicator of when the engine is ready to accept load and don't rev it or put it in gear until the cycle ends and volts are up - that gives me a startup and lube up interval directly related to the temperature of the engine.

[40grit]

hey, that's a great way to use something...I like that idea of waiting for the cycle to stop...thanks Idle chatter