cablebandit

iTrader: (37)

I noticed in the morning when I first start my car that the alternator is really putting out the juice till the car gets warm Afterwards it goes back into normal mode. Is there a way to get the alternator to go into hi-output mode at will? I thought maybe its a pcm function

Spydum

This is just a stab in the dark but, typically generators (such as alternators) produce more power when sufficienly cooled. Once they get hot, their efficiency drops, causing less power output. Not sure if this is infact whats happening, but it would make sense.

Phate

iTrader: (2)

Spydum,

That is not the case here, you can actually (at night) tell when the alternator turns from hi to low because you can hear a click (at least I can) and the lights will dim slightly.

Scott

gwj

I thought the alternator cycled on/off, not high/low??????? AFAIK the pcm controls it.

cablebandit

iTrader: (37)

well damn i need to find a way to trigger it, maybe Ken can add it to ls1edit

felton316

The 'click' you hear is probably the air pump coming on, which causes the lights to dim. Also when the car is cold, I believe it idles slightly higher causing a higher alternator output.

ChrisB

Caveat: I have not specifically verified this on the ls1, but believe it to be the case

There should be a "load wire" which goes to the alternator - a smaller guage wire, separate from the large gauge charging wire. This wire acts as a reference for the alternator and determines it's actual output (within it's rated specs). You can try putting a resistor inline to vary the voltage the alternator "sees" and artificially take it to a higher load state. You could use a variable resistor and a voltage meter to dial in what you want exactly.

Harlan could probably come up with a better way, but since the wire shouldn't be under any real load (e.g. not providing the power to do any work) I think a resistor will be fine.

Chris

cablebandit

iTrader: (37)

Chris I will try that in the morning. The "load wire" is very accessible to me as I had to lengthen it during the turbotech install

jgkinsofla

I don't know if it ever actually turns on or off - the voltage it provides to the battery and electrical system changes depending on the load.

Here's a circuit description of the charging circuit:

CHARGING CIRCUIT OPERATION

The generator provides voltage to operate the vehicle's electrical system and to charge the battery. A magnetic field is created when current flows through the rotor windings. This field rotates as the rotor is driven by the engine, creating an AC voltage in the stator windings. The AC voltage is then converted to a DC voltage by a rectifier bridge. This DC voltage is then supplied through circuit 1 to the vehicle's electrical system at the battery terminal.

The amount of output voltage is controlled by the current supplied to the rotor. The solid state regulator in the generator controls the current supplied to the rotor. The rotor current is a series of electrical pulses supplied by the regulator. When the ignition switch is first placed in the RUN position, the pulse width is very narrow. This causes the rotor to produce a weak magnetic field. This will produce a lower output voltage to the vehicle's electrical system. Once the engine is running, the regulator monitors the output voltage through an internal wire and changes the pulse width accordingly.

Also emailed a diagram of the connector.

gwj

The on/off time is controlled internally by the regulator. I think the only function the pcm has is if there's an "abnormal" voltage which the regulator triggers by grounding a circuit. The pcm then displays the Check Gauges light. But the line that supplies the reference voltage must be the one Chris is talking about. Take a look in the Helms, there's a fairly good rundown.

NoGo

iTrader: (2)

Maybe I'm going out on a limb here, but this would be great if you could directly control the voltage to the alternator exciter field.

You could effectivly 'disable' the alternator on 1/4 passes, so you're only winding it. Maybe even free up some ponies? <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

McRat

Let's say your alternator makes 100 amps when going down the 1/4mi. (It doesn't make near that).
That's 1300 watts. ~750watts = 1hp. So the most you could gain would be less than 2 hp. Wouldn't be worth the effort on a street car.