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eddielee

Curious what others think of installing a blocking diode to prevent AC Noise

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I have been considering installing a blocking diode for Alternative energy production to prevent AC Noise from screwing things up.

1600V*100A=160kW which is far more than our trucks output. This means that I could install it between the alternator and the power block to protect all electrical components easily and cost effectively. Installing a diode eliminates the possibility of AC current because it only allows current to flow one way. I would install it between the power block and the alternator then heat shrink to prevent electrical hazards.

Another option I have thought of is creating a diode bridge, however, it is difficult to find diodes with the capability of handling the current output. The only benefit to a bridge is that it would eliminate spikes due to having half of the AC wave. I don't think the average 1 max 2 volt spike will effect the electrical so much.

 

Have a look at what I am talking about

... com/Business/eBay/Energy%20Products/Diode/blocking-diodes%5Bgs%5D.jpg

http://www.ebay.com/itm/1600V-Volt-100A-Amp-Wind-Turbine-Generator-Solar-Panel-PV-Stud-Blocking-Diode-/201025568109

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It won't stop a spike.  If you have AC of some waveform coming out of your alternator, a single diode will make it a half wave.  A half wave is still AC.  Beyond that, the minor voltage ripples are bad but the big occasional voltage spikes and harmonics are the worst.  A single diode wouldn't stop these. 

I've thought about this a lot.  In my opinion, there isn't an easy, cheap, or safe way to fix this except doing it right with quality components.  You can go look at a bridge rectifier and compare how it works to what you are trying to do.  You can also look at band pass, high pass, and low pass filters.  Capacitors are typically used for low pass filters.  The amount of capacitance we would need to properly damp out all noise is actually quite dangerous.  

The one tool I do want though, is a cheap series of AC current warning lights that lights up at .01 .05 and .1 and 1 VAC sequentially.  However, I haven't figured out how to do that yet.  To add to this, I don't think an inexpensive sensor will help either.  Some sort of a transformer would be required to make it work and would require consistent frequency to work.  Even some cheaper multimeters don't pick up the AC that we have.  It took me borrowing and later buying a nice Fluke meter to get accurate VAC peak numbers from my broken alternator and other AC issue.

Edited by CSM
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CSM, I am curious how much that alternator you wrote up actually cost. I like the fact that they are made in the USA. In my opinion that makes them worth more. Buying USA made promotes US economy...

 A bridge rectifier converts AC to DC and I do not exactly see a way to install one unless I open the alternator and reman it myself. Pull other parts and create my own bridge rectifier. Maybe it would be worth it, however, a lot of work and soldering...

It seems from what you are saying, if I want to protect the sensitive electrical from possible over current then I will need to install zener diodes  in the supply lines to the ecm, pcm and VP44 individually. The zener diode is used as a voltage regulator and will stabilize the voltage...

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6 minutes ago, eddielee said:

Maybe it would be worth it, however, a lot of work and soldering...

Why do all that... Just open in up and get a new diode pack from LarryB.

http://www.fostertruck.com/diode-pack-rectifier-bridge-for-dodge-denso-alternator.html

_44.jpeg

Takes less than 30 minutes to pull the alternator off the truck change the diode pack and reinstall. Super easy...

 

Edited by Mopar1973Man
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should carry those in the glove compartment.

 

Are there a lot of parts to watch when opening up an alternator? Or is it very easy like my tractor was?

Edited by JAG1

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1 hour ago, eddielee said:

CSM, I am curious how much that alternator you wrote up actually cost. I like the fact that they are made in the USA. In my opinion that makes them worth more. Buying USA made promotes US economy...

 A bridge rectifier converts AC to DC and I do not exactly see a way to install one unless I open the alternator and reman it myself. Pull other parts and create my own bridge rectifier. Maybe it would be worth it, however, a lot of work and soldering...

It seems from what you are saying, if I want to protect the sensitive electrical from possible over current then I will need to install zener diodes  in the supply lines to the ecm, pcm and VP44 individually. The zener diode is used as a voltage regulator and will stabilize the voltage...

Call mechman.  The smaller 170 amp alternator I got was cheaper than their 210 or whatever.

Also, diodes of any flavor won't help in this DC system. Diodes would still allow half of the wave to make it through and you would be putting a ton of resistance in the system where it shouldn't be.  

I used mechman.  But I think moparmans ideas are also very good.  I kept my old alternator as a spare and will likely rebuild it myself.

Edited by CSM

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Don't brushes pop out making it harder to put back together?

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7 minutes ago, eddielee said:

Using a DVOM what is an acceptable AC reading?

Normal good - 0.01 to 0.03

Marginal - 0.05

Fail - 0.1

As for marginal it can be varied answer. Some vehicles can go well up to near 0.1 without a issue and other start having TQ Converter lock up issues as low as 0.04. Lower is best.

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So I have been having difficulties if I have a Bosch or Denso alternator.

What are the real tell tales? The Larry B's rebuild kits only cover Denso and say something about small wires going to 2 posts on the back.

I looked for Denso alternators and the ones I find look like mine. I also find Bosch that look like mine.

http://www.partsgeek.com/t11c86m-dodge-ram-2500-alternator.html?utm_source=bing&utm_medium=ff&utm_content=MP&utm_campaign=PartsGeek+Bing&gb=pp&utm_term=1999-2002+dodge+ram+2500+alternator+denso+99-02+dodge+alternator

Edited by eddielee

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41 minutes ago, Mopar1973Man said:

Normal good - 0.01 to 0.03

Marginal - 0.05

Fail - 0.1

As for marginal it can be varied answer. Some vehicles can go well up to near 0.1 without a issue and other start having TQ Converter lock up issues as low as 0.04. Lower is best.

I would like to add that typically this is measured at idle.  I found with my bad alternator would get worse readings at higher rpm and on very hot days.  

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The reason I was looking into inserting one or more diodes is to protect the sensitive electronics in case the Alternator goes out of specs, not to replace the alternators diodes without repairing the alternator too.

Makes sense to me that if these electrical components are so sensitive to AC noise, then why not add a layer of protection. A zener diode is capable of doing just this, however, I have not found any large enough to carry the full load of the truck. Therefore, I would be limited to individual diodes for components.

Added resistance is not so much of an issue at the voltage and load of the components.

When Moparman says that some trucks failed with such a low noise volume over spec, I start trying to find ways to protect myself from such costly repairs using inexpensive sensible measures.

 

 

 

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Forgive me if I'm missing something, but I don't see why the extra diode wouldn't help.  the most common way (AFAIK) for main diode pack to go bad, is for one or more diodes to get slow, which means it doesn't react fast enough and lets some negative voltage out of the alternator.  A auxiliary diode in my thinking would prevent that from getting to the battery.  One thing I would be tempted to do, because everything gets it's power from the drivers side battery, have the alternator hook to the passengers side,  that will act somewhat as a RC filter.

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It doesn't seem to me that slight forward voltage spikes are bad.

The alternator has a variance in the first place.

A Zener diode is designed to regulate the supply voltage in power supplies, If I were to install one in the power supply line to the sensitive equipment with a value of 12V-13V it would only allow forward direction current and regulate the voltage fluctuation to the component. Stabilizing spike current and limit flow one way.

Just need to know the wattage and compensate, or minimize, for added voltage drop.

Edited by eddielee

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Still looking at the wrong way. It not suppose to be any AC voltage at all. It suppose to be PURE DC or a flat line on the O-scope. Zener is only going to clamp one side of the sine wave. A very random AC noise wave might not clamp properly.

397px-3_phase_rectification_2.svg.png

 

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I agree that i was looking at the Zener the wrong way. It can be difficult to find information about some of these diodes.

After a lot of consideration and a few discussions with an electrical friend of mine, I have come up with a Schottky rectifier.

40CPQ100 40 A 100V Schottky Rectifier Diode International Rectifier

Say the left leg is connected to the power supply for the components at the fuse block and the right leg is connected to the ground, with the middle leg supplying the component with power. Stick the appropriate fuse inline with the rectifier and you have a rectified current.

This rectifier is rated 40A bypass with .61V to .77V drop @ 20A with 1.25mA to 15mA reverse leakage current. 15/1000= .015A maximum leakage which is half the alternators allowed leakage.

So from the power to the fuse #3 20A in the PDC where the ECM, PCM and IP get their power supply to the Schottky rectifier to a fuse back to supply the components with rectified power. The third leg will be grounded, preferably to the alternator minimizing resistance.

 

 

 

Schottky Rectifier diagram.jpg

This will rectify AC current, however, the main purpose is to maintain any possible AC voltage to be within specs of .03V or less to the sensitive electronics.

 

https://www.westfloridacomponents.com/T621APL03/40CPQ100+40+A+100V+Schottky+Rectifier+Diode+International+Rectifier.html

Edited by eddielee

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Problem how will it handle the high current draw or charge rates of 140 Amps? How about grid heater cycling in and out? Assuming that diode would require a heck of a heat sink? Mounting location under the hood wouldn't work in the summer time.

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The diode will not have to handle the 140A charge current as it is only supplying the ECM, PCM, IP and lift pump with power.

Pull the FMX fuse at #3 in PDC tie into the power there, run out of fuse box to the diode attached to the truck as a heat sink, through a 20A fuse and back to the #3 fuse to supply power.

Edited by eddielee

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