DIY- Alternator Test Using the "AC Ripple" Method
HTML-код
- Опубликовано: 31 июл 2018
- A basic overview of how to test an alternator using the AC ripple test method. For the full version of this video and much more diagnostic and training videos please visit my new website-
www.schrodingersboxqm.com 
Авто/Мото
am from Mauritius...
your videos are the best I have ever seen.
the way you explain on the board help me a lot
It is very kind off you to offer your help to people who don't have the chance to follow trainings at school.
You are a good man.
Olivier Pirard 👍
I used to install vehicle fleet management systems back in the day. These systems would not work on a unstable auto electrical system as it would screw up the speed and rpm readings it read from the vehicles sensors. I used a digital multimeter for convenience to measure the AC ripple voltage and discovered that readings >40mVac up to 100mVac was generally a problem created by dirty battery terminals or poor battery to GND chassis connections. Readings >100mVac was a result of a faulty charging system - caused by faulty bridge rectifiers, broken/worn out alternator brushes. NOTE: When conducting these tests the motor has to be revved between idle and +2000 rpm on heavy vehicles and idle -> +3000 rpm on light vehicles.
Thank for share you knowledge with the international community MR Schrodingers Box
.
Best video to confirm I really don't need a scope to analyze my 2012 Ford vehicle. My Autel MK808BT Pro I just bought can do maybe 99% of the common issues. Just need an accurate Amp Clamp.
I'm standing beside Mike when he made his comment and we had a good laugh at your response. Loved the information, thanks.
Good to see you're still around here Matt.
Never left! Just busy with the website.
Great explanation Matt, here's one of the reasons why I love the oscilloscope.
A greeting from Spain my friend ;)
I didn't know you had one! That's great!!
My personal oscilloscope is small is a PicoScope 2505, but it is wonderful to be able to find faults with it and be 100% sure of the failure and not change parts =)
Good information Matt. Good to see new videos. Thanks again.
Thanks bro!!
i just can tell you ...THANK YOU for share your knowledge......
KNOWLEDGEABLE schrodingers box
God bless Great tutorial thank you 👍
Schrodingers Box
From Nick Ayivor from London England UK 🇬🇧
Thanks for watching as always. appreciate your support and love my UK viewers!!
Alternators are really just AC generators except the AC is rectified into DC by the stator diodes. The dropouts you might see in the output waveforms are caused by either an open stator winding or a bad rectifier diode. An alternator with an open stator winding or bad diode may still charge the battery but the output will be reduced so the battery may never get a full charge.
Excellent analysis. Thanks.
Great videos like that you explain the cause of the problem and not just how to fix it. I think you should put more videos on your channel.
Thanks- I try to upload as much as I can.
RPM needle increases about 40rpm, then drops down about 40 rpm all the time, up.....down, up..down....... up........down.... Didn't think it was an issue until I was hauling a little utility trailer up an incline, those little 40rpm flickers turned into surging, needle would rise and fall a good 400-500 RPM's making the car surge and transmission rattle away.
I found on my OBD2 reader a graph showing the Control Module Voltage, it jumps between 14.4 and 14.8 a lot. Makes a slight whining noise almost in tune with the RPM needle flick, it could be because the RPM's are increasing and decreasing thus making the alternator go up and down, but could it be that my alternator is outputting power with a surge of .4 to .5 volts? meaning what the rectifier isn't doing its job and keeping it constant? The multimeter gets a solid 14.75 but thats a slow refresh rate device, the OBD2 scanner gets a spikey graph with a .4-.5 volt difference between max and min.
This flicker has been going for 2 years now, no codes, no check engine, 2 garages couldn't diagnose it.
Happy to see The Whiteboard of Knowledge!
Hi Matt thank you alot, your videos has alot informations iam learning from it, iam from middle east from Palestine.
Great video God bless! my alternator passes but not the ripple test my heat and cold dashboard light is out and a battery 🔋 light on but the battery is still charging.. I have a spare alternator in the trunk in case I need to install it thank you huge stress relief
Great info and well explained.....Thank you so much.
Best mechanic on youtube.
Not sure about that but I am the best one on this channel lol
Schrodingers Box lol. Guaranteed.
Schrodingers Box Always be sure to have guests who are "inferior" to maintain that truth. ;)
Hello Amigo
Nice beard. The word ripple reminds me of the wine Fred Sandford drank from the tv series Sandford and Son. I have a 98 ford exploder that came to the shop yesterday. It was charging at idle with all the accessories on but the moment you throttle up the battery light would flicker. Ripple test coming up this morning. Also has a parasitic draw. Nice video
Great video again. Thanks for the great gesture for we the unfortunate ones from the other side of the world.
Will send you an application for the free channel this week!
Schrodingers Box thanks onces more.
Actually I forgot youtube did away with private messages. send me an email by going to the "About" tab on my home page and you can send me an email from there and I'll get back to you aboput the pay site
Yet the "About" tab isn't helpful. For a start my email is "xpresit.biz@gmail.com"
For those that do not have an oscilloscope, a True RMS DMM would be sufficient to find the second failure mode shown.
Or a graphical multimeter (which is basically a poor man's oscilloscope).
really great to learn. please do a Movie about how to change rectifier and regulator inside alternator.
I sent a private message when there was a free subscription for a period of 14 days on RUclips and when the channel became on the website I sent another message and did not get a free subscription. I live in a country that does not have advanced electronic services. Nevertheless, I thank you for this useful educational channel
Can you use a multimeter to do the ripple and test and base if the alternator is good by the measurements
i don’t see how you could do that- even with a frequency measurement, you wouldn’t be able to determine a commutator dropout based on a numerical output only- that I can think of at least.
It has been way too long! Didn't know you liked slipknot🤣 thanks for sharing Matt!
Yeah I am not that much of a slipknot fan- the cookie monster lyrics piss me off but I like "Snuff" and similar. I am much more a nightwish fan actually.
+Shrodingers Box, Tarja or bust? Or are you still a fan of their latest stuff.
Thank you Matt for the video , Iam a follower from Algeria north Africa
I will send you some information for the pay channel later this week my friend.
Actually I forgot youtube did away with private messages. send me an email by going to the "About" tab on my home page and you can send me an email from there and I'll get back to you aboput the pay site
I missed this guy
I never left lol- I have been focusing more on the new website. But I appreciate the sentiment!
Thanks Matt. We have a battery tester which acts up all the time even though it was just replaced at work. It requires you to do the battery test then the starter and then the alternator every time. It's a standard test which a customer has paid for. Whenever the tool doesn't feel like working. I can do all these tests watching a multimeter except the ripple test of course. Now that I know what to look for in a ripple test, even if that tool Fritz's out I can whip out the scope and know if the alternator is bad.
Plus...I've seen alternators go back and forth from rippling to not rippling. Very bizarre. Having to test the battery and starter repeatedly for a tool to analyze a wave pattern when I've always wanted to be able to check it myself was a huge waste of time to be forced to repeatedly to add in a battery and starter test.
Like I said. We have a tool which can work, but what about intermittent problems? What about when the "battery tool" is working but it's wasting your time?
Thank you so much!
Great information Dave. Hope all is well!
Schrodingers Box I believe it analyzes ripple for only a moment. Battery testing combination tools can be tricked.
I've not seen it much, but this technique is clearly superior in this circumstance.
I'm doing great. Found a busier shop but it's farther from home. Trying to close on a little closer house. 2-3 times the land. In the country. Functional 2 car garage instead of my current awful 3 car garage.
Idiots installed the roof...sigh...hoping they'll sweeten the deal now that we have that from the inspector's report.
I hope all is well for you too. 👍
Schrodingers Box apologies. I didn't say garage in my reply. It made the car comments very confusing. It should make sense now. 2 or 3 car "garage" with the "" portion missing is just a bizarre sentence. Lol
I think my alternator is doing this and it's also causing shifting issue in trans is that possible? It threw a p0700 code one time but once cleared hasn't thrown code again but lights flicker in cab headlights taillights etc
a bad alternator can cause just about anything to happen. you must fix alternator first before determining if there is a legitimate code.
Yeah, something good to watch at last!
hahaha sorry- was focusing on the pay channel recently. I guess I left y'all with Scotty for too long hahaha!
I once "re-wired/recycled" my 94 kia pride (carbureted car). Wired the Alternator's Output directly to the 12v battery. I then noticed a year after. Whenever I use the A/C my battery runs out of power. Probably some of the windings already failed. Alternator couldn't keep up with demand.
Nice video
GREAT!!!
Hi Matt. Can I use this test to a car equip with Intelligent battery sensor?
Yes!
@@SchrodingersBoxDoes the specs. for ripple test .400 ac volts and 40 milliamps?is it correct? Can you correct me if Im wrong. Thank you
I've noticed that on a lot of newer cars the alternator can be bad and not be putting out enough or even be putting out nothing at all but for some reason the battery warning light doesn't come on like it should. In these cases the battery will keep going dead and the only way to check the alternator is an output voltage test or ripple test.
Yes this is due to the alternator light strategy. In many cars the alternator light is “suppressed” by the output voltage of the alternator “pushing” against battery voltage. if the output voltage is battery voltage or lower, the light illuminates. The problem is anything greater than battery voltage will prevent illumination of the dummy light. 12.7V would suffice. So as you mentioned before- the alternator is not putting out sufficient voltage to charge, but there is enough to keep the dummy light from coming on.
I agree. It is poor design though. Anytime the charging system is failing to keep the battery sufficiently charged over a reasonable period of time the light should come on. Otherwise the vehicle is going to fail to restart periodically without warning the driver that something is wrong.
Nice!
Nice! So a fluffy cloud is good. Bad teeth is bad lol.
HAHAHA Yeah I guess that's a good pneumonic!! I guess bad teeth are always bad on a scope- well, except for some CKPS signals I guess.
Schrodingers Box or a fuel injection wave which makes me think of a heart monitor?
I rarely got deep into studying those patterns as a surgical tech. It's the kind of thing I study and somewhat forget. The same happens for whay you teach if it's not applied. Some of your case studies are things I don't see for a couple years and I watch your video rather than to mess it up.
Does anyone know what the spikes are from he said are fine
The spikes are background from AC voltage normally created in energy generation.
Very nice and succinct
Great info Matt. See you on the other side!
Kaunas 142536 I've been to Kaunas Lithuania or Lietuva...your name any connection?
DE Nichols. Yes, the very same. Went to Lithuania a few years ago and that’s why the name Kaunas. Well spotted.
Ripple ...????they sell that at liquor stores her in NYC, Bernie ..
You get that too ..??
I put together from the comments that ripple has a lot of meanings other than what’s indicated in the video lol.
@@@SchrodingersBox thanks for the videos I really appreciate your efforts of teaching us.. you changed my life in the automotive industry my email is john0721934907@gmail.com..I really need to learn more..
Really appreciate your videos and the detailed analysis. Would you please recommend a good scanner for DIY'ers. Many thanks!
I have a few scantool reviews. My favorite is the CRP Launch Pro. it’s my main go to.
Hi Matt. Glad to see your back. Greetings from third world Canada. lol. So what the AC Ripple test is testing is the internal diodes correct? Also would it look any different under a heavy load, and when there is more heat? Like a voltage drop. Always great content sir. We in Canada thank you EH!
If the ripple voltage is beyond specs or fluctuates more than 250mv, cant you just replace the rectifier/diodes?
did you find a fix? got a test at autozone and they said it’s at 8v
Could a bad alternator cause the head lights, tail lights and cabin lights pulse bright and dim rapidly?
most definitely, as could many other things.
nice video good to see u again beards looking good
Thank you Matt. Good job. On your pay site, do you cover Domestic, Euro, and Asian smart charging systems field control and feedback. Duty Cycle and Hertz?
Yes I do!
But not in one video- the concepts are actually spread over multiple videos- some covering charging systems, some covering pulsewidth modulation, etc...
Thank you Matt. Just subscribed. Have a good night.
Enjoyed your video that is one clean vanguard
I assume you mean the vantage pro- yep it remains clean like my scantools do because when you do diagnostics like this you never get your hands dirty!!!
Where the link
To do this test I had to connect one of the leads to the Battery positive terminal, not the negative as shown in this video.
bruh. it’s measuring AC.
@@SchrodingersBox Yeah, I get a good pattern connecting to battery positive and B+ terminal on the generator. Even the Snap-On ripple test video tells you to connect to Pos. and Pos, measuring AC.
Great videos by the way 👍
Matt:
Could a bad diode in the ALT. fool the ECU into "thinking" it's the O2 sensor acting up,and go into OPEN LOOP??
I have here a 2001 Daewoo Nubira 1.6 (GREAT car,by the way,one of the best i've EVER seen,42 years as a mechanic) that is driving people crazy; at idle it stays in closed loop,but over 1000 RPMs, it's open loop all the way;,and it did not easily pass emissions inspection; ALL other parameters are ok.
I have been searching the net for that, did not find anything,and I came here from a video by Scanner Danner about a bad ALT. showing 20MPH on the speedo,while standing still;
I will try to unplug the ALT. to see; what do you think? Possible? This car has been doing this for a couple of years.
Never heard of that. Not familiar with Daewoo. Usually when I see OL after CL set, it's actually an OL3 condition typically caused by misfire detection.
@@SchrodingersBox I think there is no misfire,runs perfect and no codes,no light; however,the car was converted (aftermarket polish made kit, cheap--about 200 eur/dol--and very good,actually,and with its own ECU) to also run on LPG, (which costs only around 1/3rd of gasoline here in europe,portugal),and it goes Open Loop on either fuel,above 1000 RPM; but still running "perfect",just high on CO and HC; front O2 sensor has been checked,changed,still the same; i'll have to look into the ALT. output for AC(there is a rumble at idle that i'll have to look into...) and then into the LPG wiring,because i saw it is set up to commute from gasoline to lpg at just over 1000; i have the special scanner for the lpg setup,will look into that when i have time;
Anything relevant,I'll post it here;
And thanks for your videos,man, entertaining and useful (i also had to go look up what the heck was the Schrodingers Box lol ).
@@josepeixoto3384 I would start with a basic fuel trim analysis and see if it is perhaps going out of range causing an OL3.
@@SchrodingersBox Well,i'll get to the bottom of it!!
I spent 1/2 hour on the Daewoo Nubira 2001 today,and i found ,partly by chance(i had glanced at the wiring already)something interesting:
If i turn the A/C on,the ECU/O2 will cycle properly in Closed Loop ABOVE idle, and at all RPMS;
THe A/C pressure sensor(Daewoo -ACP) shares the 5 Volts reference voltage with the MAT and with the MAP,and so, I'll have to do some measurements,could not get to the ACP yet to unplug it.
Also, my(poor) scanner tells me Bat.Voltage 13.1!!! Have to check that; The Alt. is most likely defective, i hear a humming sound)i'll have to hook up a 14 Volt power supply to the Bat. to see what the ECU does then(Alt.is a b***** to change there,and it's been running like that for ever,and i was not hired for that...yet; i was hired just to get the car to burn clean,within the law,to pass emissions test.
I'll be back.
Solved, it's in CL,closed loop, now,no more OL,open loop;
The ACP is a NC(C being the A/C off) switch,and when it becomes NO(A/C on) it liberates some of the 5 volt ref. shared by the MAP; i left it unplugged,no symptoms,idle speed is already compensated by other means,that was factory overkill,or oversight,after all there is also no pressure sensor for the power steering effort ( this particular system also links into TPS and O2 to actuate the stepper motor to adjust the gas flow) ,but still OL would appear at random RPMs;
The front O2 sensor signal wire had been split/spliced into 2 wires (the LPG installation manual instructs it): one to the factory ECU,the other to the LPG ECU,(violet wire); cut that one,it is not needed,the LPG ECU has 4 gasoline injector emulators inside, and
the LPG ECU is set up correctly for the caloric value,so the car will not get issues with the short/long term fuel trims in its ecu when switching back and forth,and it does not;
But why OL at just above idle, coincidently the RPMs that the the car was setup to switch to LPG at? I got the PC,and went into the LPG setup and changed that to 2000 RPMs; the OL started appearing then at 2000 (the way it works is, after you depress the LPG button,and the temp is above what was set by the installer,in this case around 40ºC, what the customer demanded,the change takes place just as soon as the RPMs surpass 2000,or whatever value you set,and ,by the way,the switch is absolutely seamless) so i thought that internally,the LPG ecu was robbing the O2 signal even before it commutated to LPG ; i put it back at 1200 RPMs;
So,i went into the harness to undo the splice; i also reconnected the O2 signal wire with the proper terminal,since this oxygen sensor has NO hole,and they sample the ambient air that permeates,get this,between the wire strands and the insulation,all the way from inside the ECU; cannot function without that ambient air,they "measure" a gradient(a difference) of O2 concentrations, generating a voltage; hard to believe, but that's what Bosch,and all others, say about it; it's similar to a microphone that generates electric pulses from our voice pressure waves,for instance; or,in another scale, lol, a piezo/Spark lighter.
And it runs fine now, even with the sum of the 2 fuel trims around +8; the ALT. was found OK,charging at 14.2 V, just noisy,needs a front bearing, both of course; that and to have the injectors cleaned,which for this Daewoo i don't have the (funny) adapters for the fuel lines; but my nose(yes,at the tailpipe),now tells me it will pass the emissions test, sometime this week, (it's up to a month to the state retest)it's no longer running rich,nor with any misfire.
This is going to sound crazy but I'm getting 26Vac on a dvom. Am I right to assume the diode pack is bad or could it also be the voltage regulator.
Any guidance would be appreciated.
Hello
I love your videos
I have a question
How can I download a free cars diagrams electrical diagrams
I use BBBindustries.com
Thank you! I have a question, what if I measure with a DVOM on AC scale at the battery and find out that the AC reading is over 1.5 volts (considering that the DVOM is reading a average) can I say based on that reading that the alternator is producing about 3 volts AC and that it failed the ripple test? ( I know you said that the DVOM is not able to pick up that fast Ripple AC signal but would be an average DVOM reading enough to diagnose a bad alternator?)Cheers from Dominican Republic!
Dang thats a really good question man (I see you do this a lot). So the answer to your question is yes but you can't always rely on it. Remember your DVOM is going to give you the average voltage- so In the event you saw a high AC voltage then yes, you can confirm you would have had a high ripple. But what if you saw normal AC voltage- well, is that because the ripple is normal or is it because the signal dropouts are lowering the average of what was otherwise a high reading (or a normal voltage but you can't see the dropouts."
We call this a "false negative" in science and the DVOM makes the testing subject to false negatives despite the confirmed positives.
just like an ohm meter with false positives.
Turbotomass I wish ohm tests followed the principle of science in that it should be consistent and repeatable. Just by holding the dvom, your hands are warming it and changing the ohm reading. Especially in the winter.
I suppose if I was accounting for temperature precisely perceived accuracy would go up, but I wouldn't know how to quickly account for temperature changes at the injector, in the DVOM, and the wires going up to the DVOM.
I am sure however that I never trust first ohm tests. I let things warm until numbers are consistent.
Like trying to use ohm tests to show injectors are off from one another. So hard to keep their temperature equal.
I've often worked at shops poorly equipped to do more accurate testing. Example: I have my own fuel pressure tester but while it accurately reads pressure up, it can get stuck and not go back down.
Some random dude breaks the shops fuel pressure reader and you're stuck trying to get the same temp when ohms are tested on an injector to see if an injector is bad.
It's great when the scan tool does balance testing but sometimes it doesn't feel like it on some cars and you can't always get to injectors without disassembly of an intake and re-assembly each time. You can't take 6 hours to test 3 injectors. Lol
Using a DVOM we allow up to .25v AC. (There is some material out there that will allow for more, up to .4v AC) . This is just one of the reasons that the scope is by far the better tool, but of course not everyone has one. The fun comes in when we try to get students to learn the difference between the information displayed on an RMS (root mean square) meter versus the oscilloscope. While the oscilloscope displays everything that is going on in a circuit, the multimeter as stated averages the voltage over a period of time. The trick new scope users often overlook is the scope also measures the mean (not the average) of the voltage that it is sampling and it places that at "0 volts" of the scale on the screen. That is important to know when looking at the information on the screen, now the fun of converting from the AC that we see on the screen to DC effective comes into the picture. When measuring AC, the voltmeter displays the "effective equivalent" DC voltage. (Going with your sample of only having dropouts) If you take the positive peaks as displayed by the scope and measure to 0 you get the average peak positive voltage. Multiply that by .707 (sine of 45 degrees) and you will arrive at the DC equivalent that the voltmeter would have shown if it was sampling the same signal that you had on the scope.
If you want to try and figure out what a given a voltmeter reading would display on a scope it works like this. Remember this will give you what the average peak voltage would be, (not individual spikes or drop outs. To convert simply multiply the DVOM reading by the square root of 2. (1.414) If you do the math, .25v AC on a voltmeter works out to an average peak to peak voltage of .7v on a scope.
BTW when a tool supports it, having the scope display the DVOM value on the screen along with the waveform helps techs a lot with the theory side. Doing that allows them to take that value and then look and see how much spikes repeatedly exceed the effective value in either the positive or negative direction.
I like Johns answer better than mine lol!
I have a battery tester that shows Ac ripple as an average millivolt number. Usually numbers low like below 30 millivolts. I've seen higher than normal 100-200 millivolts from batteries that test bad or batteries with dead cells. not totally sure why that is scientifically.
If ripple test done and the result was bad. Dose this causing parasitic drain .
Your advice highly appreciated.
M.y
that’s a good question. I am not sure. the parasitic drain from an alternator would be caused by a bad diode and current would not be unidirectional. however I do not believe the diode is responsible for the AC ripple pattern- I think that’s the result of the commutators.
. Not totally sure on that though.
I like Ripple Wine.
Pagan Pink?
I always preferred red.
Thanks great video
Thanks Jesus, good to see you again!!
Thanks! Nice shirt!
❣
как говорится, не сцы, продолжай в том же духе!))
Like you man
Here Magid from Oman
Does the ripple test for Dead Memories?
If your memory was when your alternator was working, then yes.
I was referring to your shirt
Oh hahahaha-- my god I totally whiffed on that lol!!!
Now if we could just get Cardone to watch this video and check them after rebuild, before the shipping them to Autozone!
Hahaha hey those asshats can bite my ass. I submitted a video for their $5000 best diagnostic video contest and I lost to a parts changer who’s video showed to change a thermostat when you see the coolant temp gauge reads low.
Nice shirt!
Thank you mr. Schrodinger for sharing the knowledge.......my name is Mohammed iam from the people whose you was taking about them in the last of this video (3rd world) I want to join the website..... if you like and please take me away from mr.scotty kilmmer
Excuse me for my poor English in writing
Hahaha glad to take you away from Scotty!!! Send me your email address and i will verify you.
Blimey, i just look to see if my battery is flat or not, if it isn't, IT'S ALL GOOD!
And if it is... then what?
@@SchrodingersBox I assume the alternator is fine. Ignorance is bliss :)
Detroit?
Finally!!!
I know right Mike?
Beard looks good! You to need to let it grow out.
Hahahaha- yeah I need one like yours but I just can't get that grey working for me like you seem to ;-)
just stop using the Grecian Formula.
Hahahahaha... Control GX here my friend! Otherwise I'd look like Eric O hahaha.... only bigger.
Hi Matt great video, I´m been trying to send you a private msg, but unable to get your email. From Costa Rica.
Click on my name, go to the "about" tab and you can send me an email from there!
You need to expand way more than you are. You are talking about scaling and ms and all kinds of settings that does not make any sense for someone who has no previous knowledge of what you're doing there.
I'm in a third world country but I would gladly pay. But only if it's not too pricy.
No need- send me an email with your email and country and we'll set you up. The price is $3.49 US$ per month
@@SchrodingersBox That's crazy cheap! I'm planning to subscribe as soon as I get a car.
:-)
lose the pay channel and grow your subsciptions. RE: Chris Fix
Why on earth would i make such a horrifically bad business decision as that?????????
Not a right, a privilege for the privileged! Right?
If you are referring to healthcare, I can assure you that I pay for the right to the “underprivileged” to have healthcare. And if by privileged you mean I work my ass off twice as hard as they do.... who exactly is the one with the rights here???