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47re problems

Finlandese
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dripley

dripley

Posted
Posted (edited)
6 minutes ago, kzimmer said:

 

Yep. Been a while though. Unless there's something I missed.

I think part of the reason to move was also to get it out of the harness that other sensor wire were running. That kind of stuff it a bit over my head.  It has been a while since I read it also.

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kzimmer

kzimmer

Posted
Posted (edited)
4 minutes ago, dripley said:

I think part of the reason to move was also to get it out of the harness that other sensor wire were running.

 

If this is true, I'd have to ask why as well. Everything is DC. DC current does not induce any substantial noise in parallel conductors, so there must be something I'm missing.

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dripley

dripley

Posted
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9 minutes ago, kzimmer said:

 

If this is true, I'd have to ask why as well. Everything is DC. DC current does not induce any substantial noise in parallel conductors, so there must be something I'm missing.

This is when it gets over my head. I am more versed in structural than electrical. 

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dripley

dripley

Posted
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@Finlandese have you checked what your AC voltage is with the charge wire still in the OE position. Then you could change it and see if it makes a difference. If you dont want to cut the OE just put something in temporary and see if makes a difference.

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JAG1

JAG1

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All I know is that every member that completed all of W-T's grounding mod reported better than excellent results with AC ripple.

 

:poke: You can also do a search on dc systems about the need for a balanced system between positive and negative. That has something to do with it. I don't see the need to get into a college course about it we have hard enough time not getting pecked to death from chickens think they Texas Rangers.:burnout:

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dripley

dripley

Posted
Posted (edited)
6 hours ago, JAG1 said:

I don't see the need to get into a college course about it we have hard enough time not getting pecked to death from chickens think they Texas Rangers.:burnout:

I think I just got insulted but I'm not sure.:think:

I'll dwell on that a bit.

Edited by dripley
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Haggar

Haggar

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Keep in mind this is an ME trying to explain the BS that EEs belive to be the truth.....

 

The alternator does not produce DC power first.  It produces AC power and the diodes clip the AC waves TRYING to make it look like a DC signal.   The Diodes are not perfect (ramp up time, ramp down time etc. and OMG let one of them go bad) so there is a bit of a wave allowed to follow the voltage and current through the system.  This is in fact measurable as AC voltage on top of the DC circuit.   In the old days this didn't matter.... we were not trying to control and monitor on small 5v ranges that the stupid computers want to see.  But today we are.... (and If only they used 4-20 milliamps for the communication of the sensors and stuff they would not have been as influenced by stupid changes in the voltage system...)  

 

Grrrr EEs  can't live with them, can't live without them, and can't shoot them.  Its a heck of a conundrum...    They can take a perfectly good mechanical system, and with magic, smoke and mirrors, make it work great and efficient for awhile, then turn it into the craziest nightmare of problems that I wouldn't wish on my worst enemy....  /rant off.

 

Hag

 

 

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kzimmer

kzimmer

Posted
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2 hours ago, Haggar said:

The alternator does not produce DC power first.  It produces AC power and the diodes clip the AC waves TRYING to make it look like a DC signal.

 

Yep, what you're describing is a 3 phase full wave bridge rectifier. Except it doesn't just look like DC, it is DC. Current only flows in one direction. The diodes actually don't clip the voltage, but block the flow of current in one direction at all times. 6 diodes are used in a 3 phase full wave bridge rectifier.  There is, however, a small fluctuation in voltage. This fluctuation is measurable as AC voltage, and is what we call the AC ripple voltage. Moving the charge wire doesn't make this phenomena disappear. However, maybe it helps the effects be less apparent in other areas.

 

In diode based rectifier design, it is imperative to use a properly sized DC filter capacitor to cut down the ripple, especially when sensitive electronics are used. For whatever reason, this isn't standard practice in the automotive industry. One might assume the engineers tried to design around this by adding extra power supply filtering before the electronics, IE right on the ECM/PCM. Even in our trucks, the ripple seems to be manageable until the alternator diodes fail open circuited.

 

I'll be wiring in a 200A solenoid in series with my grid heater power supply that will not allow the grids to be energized while the truck is running. This should help save my alternator diodes, leave the grids fully functional before starting the engine, with no manual intervention or push buttons, and avoid any CEL's.

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JAG1

JAG1

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Isn't there a potential for explosion with capacitors. You hear and read so much......... Capacitors are a band aid approach, that coming from another's perspective I read. I do know that with DC systems there is no perfect system.

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Haggar

Haggar

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what Kzimmer says! 

 

Again from an ME's perspective, once we get past the smoke and mirrors, they (the EEs) make a squiggly line and want me to eat it as a straight line.  It's squigglier closer to the source than further away.  And since the smoke and mirrors gurus that came up with this didn't give us the right stuff to do it right, we are gonna move the squiggles behind the only thing that we have that resembles a DC filter capacitor, the batteries.  We have two of them so that should un squiggle the line some.  :)  :cheers:

 

Agreed the AC gets really bad when one diode is failed.  Sometimes this is caught early (alternators that drain your battery when the engine is off,) and sometimes not seen until too late (hey batteries don't die and my volt meter says I am charging, but my lights flicker and the flicker changes with RPM.....). It also seems that there is some AC occuring as the brushes and armatures wear.  Not sure if the carbon is making a trace for alternate voltage paths or what. Most of the alternators that are available are rebuilds.  The rebuild guys don't replace EVERYTHING, just whats broken.... and what is broken is only according to how well they tested it in the first place.)

 

I really think a big source of issues (and the problems we keep worrying about) is whoever decided to move the voltage regulation to the PCM.  Just what in the world does the PCM need to be worrying about the stupid gross regulation of  battery charging voltage?   So now we have two theoretically the same, but separate 12v sources (three if we include the squiggly thing that should be straight)  that SHOULD be the same (but the grounds are not bonded together exactly like the positives are) but with just a bit of grounding issue turns it into two (or more) different systems relative to the PCM....  The PCM sees the ground of one battery and the positive of the other battery.  voila magic smoke at worst, potentially weird regulation at best, and nothing to help make squiggles straighten up.   (why, just why,  when an alternator failed it would die, not potentially take out the PCM with it....) 'splain it to me Lucy!

 

and Jag, no capacitors don't really explode (i guess a really big one could but still not see explosion as the proper description)  Usually when they fail and the magic smoke comes out, they split open, and if bad enough, some of the solid magic smoke leaks out too.  unless you are in a cave and using a stone tablet with chisel and hammer (gosh  sometimes i swear i wish I was donig it that way... so much simpler) you have hundreds of capacitors around you.   usually when they die, the tv won't come on, the AC won't come on, etc.  The circuit gets grounded and the appliance stops.  The grounding isn't usually enough to pop a breaker, just short to open circuit.  

 

Just food for thought guys.  100% ready for some beer. 

 

Hag

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