Originally Posted by apg camo

Will the led 194 bulb work in the charge light port? Will the charging system still function as if there was a regular bulb? I know 12 volts has to go through it and then to the "I" on the regulator. I'm just not sure if the low amps draw of the led would adversely affect anything. Anyone know?

Originally Posted by apg camo

Will the led 194 bulb work in the charge light port? Will the charging system still function as if there was a regular bulb? I know 12 volts has to go through it and then to the "I" on the regulator. I'm just not sure if the low amps draw of the led would adversely affect anything. Anyone know?

Originally Posted by dixie460

Yes but understand that you're gonna give up part of the functionality of the warning light. That bulb gets V+ from the ignition switch and "grounds" thru the field windings in the alternator. When the alternator is working right, the field windings are also at V+ and therefore the bulb ends up with V+ on both sides of it so it stays off.

^The bulb grounds through the regulator and when the feild voltage comes up then the regulator powers the bulb giving the bulb a net zero voltage.

If the alternator quits producing power, field voltage goes to zero (it's generated internally after the initial excitation) and the bulb now has a "ground" so it glows. Current flow is from battery --> bulb --> field.

^This is correct.

If the battery takes a dump, battery voltage goes low and the bulb again has a "ground" since it's being fed V+ from the field windings on one side and has a dead battery to "ground" to on the other. Current flow is from field --> bulb --> battery.

^This is wrong, if your battery took a dump, it either goes open aka no battery and the alt can run the vechile like this but not recomended and if the battery were to short out internally, the alt would be driving a dead short or very high load and the engine would stall from low voltage. There is no way you can get a current draw backwards through the bulb. The bulb doesnt tell you anything about the battery just the alternator.

An LED will only conduct in one direction, so if you connect it so that it'll warn you of an alternator failure it won't work to warn you of battery failure. Now personally I ain't ever seen a battery fail where the idiot light came on, but that's the theory behind it.

Keep in mind that every "battery" light bulb in these trucks have a 510 ohm resistor in parellel for the only reason if the bulb burns out so the alt will still get the exciter voltage to turn on. The diode action of the LED doesnt cause any problems except you have to put it in the right way for it to work.

Also, you'll want to protect the LED from overcurrent yet make sure that enough exciter current gets delivered to the field windings to get the alternator going. Sounds hard but I think it can be done quite easily. Might need a resistor in series with the LED and/or replace the existing resistor that bypasses around the bulb (provides a current path in case the bulb is blown) on the back of the cluster.

^ This can only happen on an extreme over voltage of the entire electrical system, the LED already has current limiting in it unless your useing raw LED's. A standard bulb is built for 12v, it will only draw its designed current at that voltage and no more.

Originally Posted by Eddiec1564

I found what IC Ford is using for the voltage regulators. Its called a CS3341 and here's the data sheet info in PDF. (not direct link to PDF but to that page with the PDF)



CS3341: Alternator Voltage Regulator Darlington Driver


There is a schematic which is almost like what Ford is using in the 2G and 3G alternators. A few component values were changed but overall circuit is the same.

Originally Posted by ifrythings

I dont know who told you that but Ford doesnt use that, they do everything descrete, take any 2G or 3G regulator apart and all you will find is a thick film process board and you can see all the individual resistors and transistors. They aint going to pay a buck or to when they can make it out of 10 cents worth of parts even with it being more complicated.

Originally Posted by ifrythings

This thread has a lot of miss information in it....

The bulb grounds through the regulator and when the feild voltage comes up then the regulator powers the bulb giving the bulb a net zero voltage.

Agreed.

...if your battery took a dump, it either goes open aka no battery and the alt can run the vechile like this but not recomended and if the battery were to short out internally, the alt would be driving a dead short or very high load and the engine would stall from low voltage. There is no way you can get a current draw backwards through the bulb. The bulb doesnt tell you anything about the battery just the alternator.

Like I said, I ain't ever seen a battery fail where the idiot light came on, but that's the theory behind it.

Keep in mind that every "battery" light bulb in these trucks have a 510 ohm resistor in parellel for the only reason if the bulb burns out so the alt will still get the exciter voltage to turn on. The diode action of the LED doesnt cause any problems except you have to put it in the right way for it to work.

Yep, know about that resistor. Only reason I mentioned it was the "theory" above.

This can only happen on an extreme over voltage of the entire electrical system, the LED already has current limiting in it unless your useing raw LED's. A standard bulb is built for 12v, it will only draw its designed current at that voltage and no more.

You're absolutely right, it does have current limiting. Not sure what I was thinking. Lol.

Put a standard 194 LED replacement bulb in and youll be fine.