Electronic geeks required
 

Okay, the battery thing must be settled. WHO on this board has/knows how to use/can take some measurements of alternator ripple at various points?

Factual real time data, NOT theory. reality.

I think this can be a great thread, or a nightmare, I also imagine VB will be watching close.

What kind of data were you looking for? My multi-meter will read both DC and AC voltage and frequency at the same time.
Another think to remember is that what is running and the condition of some parts are likely to effect the results.

I put a scope on my car many years ago when I bothered having a stereo in it....alt whine was the issue.....

I read 700 mv of ripple on the output stud, and much less at the battery, of course....but it was still there, and of course I forget the numbers.....but I was surprised at the 700 mv level being so lo....

If you want, I can get out my old Techtronics 453 scope, and look around again.....my Fluke meter is kinda old, but still werks….. lemme know watt you want measured and where.....

Dig it out. Lets play.

See if you can get screen shots of battery neg to alternator post, battery neg to starter post, and battery neg to battery pos post.

Maybe alt post to frame ground for giggles.

Great timing, just got finished measuring the alt out stud to engine ground.....only measure I did so far....guess WATT!!!

200 mv ripple is all I see, and I even slowed the sweep down to a ten second rate....no lite on the screen except for the 200 mv peaks seen when I speed it up..... 17SI fresh alt, all fans and a/c running...dual spals, computer injection, C4 blower, properly grounded, all my 'lecTRICKery connections are solid/soldered, cleaned and sealed funny about that alt, the really old 17SI crapped out after many years, so about a year ago, I got another under lifetime warr from AutoZone.....and wooden I know it a very short time later it crapped out AGAIN after just 10 months....and the thing went to super high voltage pegging the meter at 18 volts and the HVAC motor was raising HELL, witch is watt alerted me to it....I about shit....I let it cool down and tried it again the next day....same shit.....HELLO AZ, I need another one.....so far so good for a couple weeks now.....Kan't win......

Hey Jeff, you happen to know anything about ONAN commercial 6500 GenSets?? 6.5 kw 27 amps at 220?? we bought an old ATT service van chebby 3500 series for a work truck it was an ATT wagon....and so I trying to figger out how to get the Genset outta there, and it won't start, I want to sell it, apparently they going for like near 2 grand here.....while others are less than 1/2 that price....go figger.....

If I had that experience with an alternator from AutoZone, I'd just eat the cost and go to a reputable shop that only rebuilds alternators and starters. Those guys use way better rebuild kits and they (usually) do good quality work. The HD alternator I got off the 87-91 Caprice, got checked out and redone by such a shop close to me. Zero problems, three years later. Just an opinion, as despite the lifetime warranty and 'free replacement', your time isn't free!

Just an afterthought, if you have a Carquest Auto Parts or NAPA, they usually sell a better line of parts, than the Autozones, PepBoys, etc.

Hated to see him shut down, but the ex.mil guy with a GREAT auto electric shop not but 3 miles away retarred entirely and so no more.....honestly if I knew where to get the AMERICAN made parts in a timely fashion, I"d do it myself, like I have done many time in the distant decades of the past.....

Gene, NAPA has all the parts. I have bought all Delco parts from Rock Auto. I still have some NOS starter brushes laying around.

Used to be $25 for all new bearings, brushes, diode trio, blah blah,.

https://cimg5.ibsrv.net/gimg/www.cor...690cdd5fbe.jpg
When I installed the Spals, I installed this Powermaster unit. High amperage at idle. Dual internal fans. Diodes mounted externally with air blowing thru the heat sink. DIRECT fit on brackets with SI dimensions.
Been on there 8,000 miles, and runs very cool.

AND, its a few pounds lighter.

Your on.
I just have to do a few chores here first. In the spring, I'm jambing a two post in the garage. Lots of stuff to do to get ready.

Gene, let us know when you can measure the ripple at the solenoid stud and the battery posts.

Oh boy...can't wait to hear or see the real data!

Redvette2

I have access to a good scope, but can't measure anything on the old cars until the spring.

Trying to do a measurement from the battery negative post to the alternator with a scope or meter can be troublesome just due to the effect the long test leads can have. You can lay out a negative test lead long enough to make that run with the far end connected back to the positive probe and still read a fair bit of electrical noise. Typically, it seems to 60Hz AC that gets induced. A 3-phase rectifier has a ripple voltage that is 4%, so around 0.6V of ripple would be expected at the alternator output and it's not hard to make long test leads with the ends shorted together that read similar levels of noise voltage.

I suggested the same ground for all 3 tests to keep some control over the readings to be accurate.

Whatever you "EE" compadres agree is accurate is perfect.

Inquiring minds just want to know. Some decisions about these cars, probably most, are subjective.

I like facts, and what ever we find is real data, no different than all the dyno sheets we see.

I "thinkl" I read some of the later units like the one I use has less ripple. (Maybe Boones Farm). :thumbs:

So many variables to try to get a really accurate measurement...probe compensation, probe lead length, probe ground lead orientation, scope band width/frequency response, scope calibration, scope internal ground circuit, etc. Likely the best you could hope for is relative measurements by keeping the measurement hardware standardized as much as possible using a fixed shortest lead possible setup.

Redvette2

And we can put your C3 on the Dyno when you get here as well and see what that bitch puts down at the pavement:-)

im at 525rwhp:-)

Dang....if I remember right those things cost a small fortune. Let's see some cool four probe color plot pictures!

Redvette2

,You posted dual diodes. If that actually means it is 6-phase and 12 diodes then it would have less ripple compared to the typical 3-phase, 6 diode unit. That wasn't a factory GM configuration for the alternator, but it could be something Powermaster did on that unit for more power compared to the stock unit it was based on.

Dual fans.....External diodes....

Well, count them. If there are 12 then it might have a lower ripple compared to one with 6.

I'll go look. Meanwhile, I copied this, and I think it's what I read before about the later units:

In the early 80s, GM began an experiment called the “X” car many of us remember as Chevy Citations and Buick Skylarks. These FWD transverse mounted four-cylinder engines were quite underpowered and prone to stalling and even strange tail pipe vibration as the two-pin GM “Delcotron” alternators were immediately turned on to a full-field condition in order to take care of a sudden increase of 12-volt accessory demand. Not quite ready to trust “F.R.E.D.” to handle voltage regulation, the GM/Delco Remy CS series alternators were born in order to gently ramp up the field current when a sudden current increase was demanded. As the alternator sensed internal voltage at the output post or external voltage at the new four-pin regulator’s new “S” terminal (tied to a strategic spot in the wiring harness), the smarter voltage regulator would ramp up the PWM of a duty cycle running at 400 Hz. Since this was all internal to the alternator, unless you were a rebuilder or a geek, you would have never known.

https://cimg4.ibsrv.net/gimg/www.cor...998256ae89.jpg
Just 6 diodes. I do like they are external, (Cooler), and you can change brushes without disassembly.

Here's a really external one- 12 diodes

https://alternatorparts.com/quicktif...rectifier.html


https://cimg7.ibsrv.net/gimg/www.cor...58774e2ebc.png

It may have 12 diodes inside but it's still a 3-phase rectifier so it doesn't help with the ripple much, if any. The diodes must be in parallel.

The CS alternators also have much better idle performance and are more efficient which I would believe are the main reasons for that design. The SI alternators used an analog regulator so they could have had a delay added by adding a capacitor if that was the only change desired.

95Amperes at idle. Weighs 12 pounds. Win win.

Well, when needed, I will change to a CS 144 maybe I can junkyard one cheap.....

hate to guess what an AMERICAN rebuilt one would cost......;-(

Wow...95 Amps at idle! Curious what is that kind of power used for?

Redvette2

Not me. I liked the weight, and I can install a stocker in 10 minutes.

https://www.summitracing.com/parts/pwm-82071 Made in USA, 12lbs, just switch the sheave, plug in adapter, and done deal.

Go back to stock SI, unplug adapter, switch sheave, done.

If you want an even better alternator then go to the AD series, AD-230 or AD-244.

Even not using the full 95A at idle, you need around that current to maintain a steady 14V at idle with electric fans and lights and such all running at one. Heck, just the 2 brake light bulbs draw almost 4A when you press the brake pedal so it all adds up.

So Gene, had a chance to work on this? Inquiring minds want to know.

How many EE’s does it take to change a light bulb?
 

Three: One to insist the schedule needs to be moved to the right,
one to complain that the budget is too tight,
and one to say it can't be done. ;) ;) ;)

Sorry Jeff, too damn cold here the last few daze, and other issues running wild....and having just put the 3rd alt in there, I let it fail first.....be a while, I hope.....I did use a CS144 on a camper I did some dozen years ago...feeding a marine deep cycle for the inverter, as well as the 24 series for starting....

but these daze my spine and other arthritic areas just slo my enthusiasm to nothing anymore...damnit....

Hey buddy. No hurry in this quest.
We just need volunteer #2.
Mike>? Do you have access to a scope?

Lol. I have experienced the last two in the past.

Sure. See post #5. The more results we can have, the more conclusive.

Here's my weapon of choice lately from EBAY for about $45. It's a DSO168 portable digital storage scope. 20Mhz bandwidth, no laptop required.


https://cimg7.ibsrv.net/gimg/www.cor...3a0e7623d5.jpg

The more data, the better. See what you can measure.

Ok, you made me curios so I checked my '71. When I converted to electric fans and EFI I swapped out the stock 10SI alt for a 12SI. It's an el cheapo Autozone rebuild, but it's been fine for years. With fans running half speed + stereo on (big Rockford Fosgate amp from the 90's) I got this:

Alternator stud: 0.18V
Battery: 0.016V (notice the extra zero in there)

Btw, no need for a scope to measure ripple. A good 'True RMS' volt meter is all you need. I use a Brymen BM829s.

Can you measure one more item? The starter post to battery negative.

Too cold to crawl under the car and don't like doing that with it running. It will be close to the battery readings anyway.

And I don't think I can get to the starter post with my long tube headers without burning most of the skin off my hands. lol

Fair enough. Thank you for your efforts. It starts the baseline.

You do know that meter data doesn't prove much without knowing the wiring configuration?

True. The "assumption" is stock wiring. It might be prudent to key that into the quest.

Been watching this thread, but have been tied up with unexpected family stuff the past few weeks. Finally getting caught up. I've got a couple scopes that have been gathering dust lately, but I oughta be able to play around a little on this topic. The '69 is apart right now to take some more weight out of the car, but my "84 is running. I moved the battery in it to the rear compartment for better weight distribution, so it ends up electrically configured somewhat similar to a C3. I run small batteries in both cars for reduced weight, but I can probably scrounge/install a regular size battery too for a bit of comparison purposes.

Back in the day...30 years ago when I worked for Kenwood- Car Audio- we did a lot of testing trying to solve the infamous "alternator whine."

On a brand new at the time 90 T-Bird SC - The frequency was in the couple hundred range @ 1800RPM. So 100Hz sounds correct at idle.

The frequency will vary directly with the rpm if that actually is alternator ripple. So, try revving the engine and see what it does.

Good read on the subject
 

The following article is a good reference for this discussion.

https://moretraction.com/2018/08/31/2416/

Thanks BS.

Good article- can even download it in PDF

Sort of confirmed my dirty bus and the clean buss thoughts- AND the often debated large a$$ wire I run-

THANKS for posting it up!!!

BTW- I like this- have only see 1 post versions


https://cimg3.ibsrv.net/gimg/www.cor...cc447396f1.jpg

Interesting article. They are correct about solenoids switching can produce voltage spikes and have the idea behind using ohms law to calculate voltage drops correct, but they make their point by saying a piece of 1/0* wire has 0.1 ohms of resistance. Who uses about 1000' of 1/0 wire for the circuit from the battery to the junction block?

* I'm assuming they mean 1/0 wire because 0/0 wire doesn't exist. It's either 0 or 1/0, as in the gauges go 0, 00, 000, 0000 or 1/0, 2/0, 3/0. 4/0.

That's not the issue. I looked that scope up when you posted it and it said 35V peak then you get a 10x probe which should allow it to measure up to 350V peak.

The probes have a little adjuster in the connector base. Make sure you connect the probe to the compensation terminals and then adjust the probe (with a plastic tool) until you get a clean square wave.

1/0-Probably what they meant.

However- if you figure the ambient temp the wire sees under the hood- .1 Ω might not be too far off for a 15-20ft run in a car.

Richard

I meant 1000' in the last post. 10' of 1/0 is around 0.001 ohms. I highly doubt it gets hot enough when used in a car to make the resistance rise to 0.1 ohms. Maybe 0.0011 ohms or something like that.

I think if your using 1000' then you're probably going to find you have bigger problems than the resistance.

I agree that the .1 ohm number in the article used is too high. More like .001.

The basic principles they discussed are sound, but they do not include the alternator which is producing much of the needed power. My battery is in the rear of the car, so I'm not sure if the alternator ground is more of a player than the battery ground.

And what about the battery fuse? That's a fairly high resistance.

I also agree about the no "butt splices"

I get it-using the 1000ft versus 100ft- big difference.

BUT- the point being is the ambient temperature in a car under the hood- changes things. Not only resistance in the wire- but what about alternator performance- more ripple? What about chemical reactions in the battery(under-hood vs in the trunk)?

It might be small- but in the real world- it adds up.

Just like the percentage interest I receive from my savings account- might seem to some it really doesn't matter- but at the end of the year- big enough to get a 1099 on it- so yea- I'm not going to discount it.

Richard

If done correctly, I.E. crimped with the correct tool, soldered, and insulated correctly, they are fine, and quite often necessary.

I agree. I've only seen splices fail due to extreme mechanical stress or because they weren't done properly. If properly done even years later with large currents they can be thermal imaged with no temperature increases at the splice.

I'm talking about unsolderd mechanical butt splices. If done correctly, yes. But how many people you know don't have the proper tools or experience for good connections? The right tools can be expensive.

I've seen my share of loose butt connectors. I've also seen some cold solder joints, but fewer.

If you're going to solder it anyway, no need for a crimp connector. My 2 cents.

Getting back to the original thread. Sorry I don't have any real measurements because my wiring is far from stock.

So I'm stuck with theory. As we modify our cars with stockish wiring and add more electrical loads, you're going to see more ripple. The alternator, as a 3 phase bridge rectifier supply is going to create ripple. Roughly 14% of the output voltage. The battery acts as a filter to smooth this out. As the alternator is required to produce more current, the battery will be less and less effective as a filter. The distance between the battery and the alternator, the battery condition and the gauge of the wires from the battery to the alternator all will affect the battery's filtering ability. If you're reading more than 14%, then there is a good chance it's a PWM load or inductive kickback possibly from the coil(s), maybe electric fuel pump or electric fan.

If one of the 6 diodes in the alternator is shorted, I would guess you'd see some ripple also.

My apologies again, only theory. My non standard wired car should be running again shortly. I'll do some measurements for comparison with huge load shifts. I'm curious now.

I think the weather is really bad timing for this thread.:yesnod:

Never had my but connected, but the on the other hand, the connections never loose until they came.....

how ever, on my wife's damn hated 01 Focus, I changed alt some years ago, and so it was checked out fine, turns out a bad solder connection to the tab from the freeking FACTORY failed, and the output wire was just hanging there next to the firewall, never noticed it somehow due to funky design....so out alt in place after wire was soldered by ME.....then the alt failed a couple weeks later, back to AZone and got another under lifetime warranty......PIA, HATE THAT CAR!!!!!

as for ripple, just rund the fans main current off the alt out stud and get hell over it, I don't bother with PWM controllers, I let the computer decide to turn on/off the fans, KISS principal certain asspects of crap just don't need to be over engineered......only trick I MAY consider is maybe putting the fans in series and when temp needed, switch to parallel be cute, but I too lazy....

Can you do it again across the battery posts, and ground to starter post?