Ever put Diodes in series with excite wire?

[JEFFYBOI]

So I seen a few youtube videos where someone had put 2 diodes in series with there excite wire on there alternators wiring harness. He shows a increase in voltage by .3-.4 with alternator cold and hot also. Im not sure I completely understand how it works but I think it basically tricks the alternator to work harder based off the batteries voltage ( not sure) Anyways I was wondering if anyone knew anything more about this?

[TheMonolith2001]

It is most likely something specific to that vehicle. A lot of cars have little tricks you can do to make the alternator work harder. Usually you buy an external voltage regular. On my jeep there is a temperature sensor underneath the battery and if I wire a resistor or better yet a pot knob I can trick the computer into thinking the battery is a different temperature and get higher or lower charge voltage.

[SnowDrifter]

A diode creates a fairly consistent voltage drop across the wire.

The excite/turn on/whatever you want to call it wire serves 2 purposes; 1- It powers the voltage regulator and supplies the current necessary to energize the rotor. 2- It acts as a reference voltage for the regulator

With that in mind, paying attention to point #2, a drop in voltage across that wire would cause the regulator to think the voltage is lower than it really is, increasing the charge voltage to compensate. Generally each diode is a .7v increase. I'd suggest 10 amp diodes, 2 of them in parallel. Reason being: If the diode fails open, the other diode will allow current to pass, therefore not leaving you stranded because your alt isn't getting power. Not concerned about a diode failing closed in this case because it would be a non-critical failure. Your charge voltage would revert to what it was before the mod.

That being said: Why do you want to charge at a higher voltage? What are you intending to gain?

[JEFFYBOI]

A diode creates a fairly consistent voltage drop across the wire.

The excite/turn on/whatever you want to call it wire serves 2 purposes; 1- It powers the voltage regulator and supplies the current necessary to energize the rotor. 2- It acts as a reference voltage for the regulator

With that in mind, paying attention to point #2, a drop in voltage across that wire would cause the regulator to think the voltage is lower than it really is, increasing the charge voltage to compensate. Generally each diode is a .7v increase. I'd suggest 10 amp diodes, 2 of them in parallel. Reason being: If the diode fails open, the other diode will allow current to pass, therefore not leaving you stranded because your alt isn't getting power. Not concerned about a diode failing closed in this case because it would be a non-critical failure. Your charge voltage would revert to what it was before the mod.

That being said: Why do you want to charge at a higher voltage? What are you intending to gain?

Well you would be gaining a higher charging voltage. As long as its not charging over 15 V it should be ok. I am running 14.6 cold and when the alternator is hot sits around 13 + or - 0.1 @ idle. Now I know its not going reduce voltage drop under a load but with stereo being off and alternator hot I should get a slight increase in charging voltage... Yes? I idle about 700 if I just tap the pedle to 750 rpm it jumps to 13.9-14V hot. I think all my alt needs is just the slightest boost for charging voltage its border line low.

[SnowDrifter]

Seeing 13v at idle and a bump to 13.7 when you rev the car has nothing to do with the voltage set point on your regulator. It means your alt isn't putting out enough power at idle and you are dropping to battery voltage. Even setting the alt to charge at 20v won't help you with that

IMO your current set points for voltage are fine. Lots of folks have a hardon for charging their batteries higher than they should be. Won't gain you anything except putting more wear and tear on your batts

[JEFFYBOI]

Seeing 13v at idle and a bump to 13.7 when you rev the car has nothing to do with the voltage set point on your regulator. It means your alt isn't putting out enough power at idle and you are dropping to battery voltage. Even setting the alt to charge at 20v won't help you with that

IMO your current set points for voltage are fine. Lots of folks have a hardon for charging their batteries higher than they should be. Won't gain you anything except putting more wear and tear on your batts

I understand reving my RPMs and the voltage regulator have nothing to do with each other. I think im gonna get a good tune up . Its starting to idle poorly. I think that should help really. Its been fine for months I just was concerned my batteries wernt getting the charge they need when my alt is running hot but no problems so obviosult its been working fine and keeping them charged.