Alternator internal component testing  

I watched this video about 3 years ago and thought it was outstanding . I just wayched it again today, and will probably watch it again. Very good video !!

I fixed my alternator using this video. Taught me how to diagnose the problem. Found an issue with the 18:22 rectifier on mine, searched online for the part number and part I needed, ordered the rectifier and new brushes ($38shipped w/tax), installed them... tested it out at autozone... and tests showed 100% good. Previously, the test at autozone, showed bad. AWESOME!

Incredible video and very well explained! I took my alternator to get fixed by a professional and I wanted to do my research to understand why it failed and what was repaired. Im a mechanic of almost 5 years and I will continue to keep learning on how to repair car parts instead of replacing. Thank you so much sir!

Great video explaining how all the components work. If your alternator fails it’s 99% caused by worn brushes. Before brushes completely wear they cause sparking which can damage the slip rings through overheating and premature wearing. If you get a red battery warning light on your dash don’t ignore it. Generally, swap out the brushes and you are good. The hardest part of any alternator repair is getting to the alternator and getting it in and out of the car!

Best video to learn about how to diagnose Alternator for faults.

I actually work as a car mechanic and I never really figured out how to measure an alternator when I was in school though we took some apart but this video has helped me a lot, finally I know how to test it. Thank you so much for a fantastic video!

An absolutely fantastic primer on alternators and testing their components. I wish my college teacher would have been that good. Hats off to you sir, and thank you for this great presentation.

Thanks Andy, especially for emphasis on the diode setting in the multimeter, I thought my rectifier may have been faulty, I just had to correct the setting on the meter, just as you mentioned, make sure it’s set for diode testing, the symbol popped up on the screen and then all checked out ok.

this is one of the best videos regarding inspecting and testing an alternator I have seen. Well done. Good explanation while still relatively technical. Thanks.

I watched probably 10 videos already and still confused how to test an alternator. Once you explained the voltage regulator at 3:27" it all became clear. Thank you!

probably this is the best video out there on how alternator works and how to properly understand what's going on to fix it, thank you very much

As others have said,I work as a hgv mechanic,but never really understood alternators,mainly due to the lack of this type of in depth training at college,what an excellent video thank you.

Absolutely fantastic work. Thank you. I used to have fractional hp motors rebuilt (1970's) but no body does that anymore. Seeing this I really understand my vehicle so much better. I have found kits here in the States to rebuilt alternators. I'm amazed. Like you say shops won't do this because of labor costs but I can fix my own. Empowering.

I never leave comments but have made an exception. Beautifully clear diction and video thank you

Definitely the best and easiest understood video I have seen on testing alternator components with a multimeter, exactly the video I was looking so I can repair my alternators rather than replacing them and not knowing why the failed, thank you Andy Mechanic for making this video.

Helped me a lot diagnose my alternator. Turned our my stator had a break and was making contact with the windings. I wish I checked this before replacing the worn out brushes.

Excellent in depth, detailed explanation on alternator function. Very very very well done!

The best video on RU-vid describing how to breakdown and test the various alternator components. Excellent job! Just what I was looking for. Thank you very much!

I've only just found you thanks to some land cruiser forums! I'm an automotive student at a polytech in tauranga and you seem like such a better tutor than I have, used this video to get my cruiser up and running

Thank you for a great video on testing the components of a Denso alternator! You explained all of the parts and their operation wonderfully. Not another instruction like this that I could find.

Andy check the time you posted the video and now(25/12/22) , I'm so grateful for the best lesson on alternator testing as I tried watching even by passing your video not knowing it had the full package. Thanks and happy Christmas to you and the family at large. Exceptional presentation ever!

This is an in depth training and I thought that I was in a class. Very informative and you took your time and spoke clearly. I'm not a mechanic but I'm trying to fix my alternator myself. On top of that, you also explained what each components do. You are a wonderful trainer and an educator. God bless you

At last, a real alternator video, not the dumbed down version we normally see on youtube! Thanks!!

Excellent video....well put together...concise....ability to keep the viewers attention with your very clear and precise instuctions

This is the best alternator repair video on youtube.

It doesn't get much better than this. Excellent!

Excellent video...always check the rectifier first before taking apart the alternator, 90% of the time that's the problem, sometimes you can even get it off without removing the alt. from the car.

I found three alternators n took them home. Now that I saw ur video I can test them to find the problem n hope to repair them. I live in remote Community n this will help me a lots. Good video.

Great video Andy! I went to Unitech nearly 20 years ago (shout out to Duncan Wales). Great that that they still have guys like you!

Excellent stripdown and diagnostics

As an educator myself, I must say that this is one of the best videos regarding inspecting and testing an alternator I have seen. i must commend you as well on making videos of the topics you are going to teach. the students will learn much from them also they can be watched over and over again. Well done. Thanks.

Thank you, this saved me soooo much money. Tested all but voltage regulator and found all defects (missing bolt) on ground from regulator. Now its working perfect. Thanks again.

Your videos are always worth watching. This was great . I pulled an alternator at the junkyard today to use as a trail spare and I want to bench test it. I spent an hour looking at writups and videos of people testing output on the car but nothing that I needed to see. Then I thought I should check Andy’s channel and sure enough you have it covered! Cheers

Very well explained!! Kudos to you. Thank U

A very detailed and instructive video. You have an understandable way of teaching. Other videos on the subject make my mind drunk.

Great video ! Very impressive ! Hard to find this kind of basic teachings nowadays ! I subscribed.

this was a great refresher for me, I used to this in my high school auto shop class

Excellent presentation on how to test each of the Alternator components.tqvm Sir.

Excellent video on the very popular Denso alternator. Thank you for posting such an informative and useful (to me, at least) video. I believe your testing of the Denso regulator is maybe the only clearly explained one available.

Thanks Andy, you explained it clearly and made it easy. I'm beginning to fix alternators now. Thankyou very much

You are awesome in your video and it's descriptive nature. Very comprehensive then you're wearing a great shirt too!

You are such a good instructor. I have really enjoyed watching your video. Keep it up.

Excellent video for diagnosing the internal components 👍thumbs up!!! 17:13 USA

This video is very impormative for me.. clearly explanation..about alternator mechanism..step by step..one by one..up to assemble material.. thanks for sharing your video ser Appreciated.. great job..

What a lesson! Thank you very much for this comprehensive video!

Such an inclusive amazing detailed testing and analytical display A+++++++++ very valuable best regards ,Bob Alabama Parts company owner

Very useful video. Thanks Andy 😊

Excellent teaching and useful technical revelations. Thank you.

Patrick kabunga. thx very much for all those educative videos, you make me love my trade

Thanks Andy ! Yours video is very good . You explanations easy to understand .

what an excellent video, clear communication and all the information, much appreciated!

Hai Andy like the way you teach from Zambia

Very good sir I am motivated

Very informative presented session lm sure l will refer to it again thank Very much.

Hi Andy, Greetings from Ireland. Thanks, this is such a great video. I have never had to deal with an alternator issue before now. The instructions are so clear and easy to follow. I would have been lost only for this. The best thing for me (in all your videos) is the detail you go into to explain what each component does and not just simply, do this or do that. Keep up the good work Andy, I hope you are keeping safe and well during this Covid time. Take care David

thank you sir this is one of the best videos

Super klip,do sada najiscrpnije objasnjen rad alternatora!

Excellent video clear explanation and the very best I have seen!!Thank you sir.

Thank you the best explanation so far.

You being very helpful and you very informative....thank you sir 👍

A very usefull video much appreceated .

Thank you very much. It helped me to understand better how to check the alternator.

Great video & well done! When you were checking the rectifier diodes you were saying .495 "Volts" instead of ohms. I suspect that nearly all your viewers knew you simply misspoke. Very well presented...& assumed nothing.

Greatest video ever made on RU-vid thank you sir

thank you very much Andy sure am happy with your technology

This is a great refresher for me too. Thanks much for making this video. It’s so nice to be able to watch this and get refreshed when I havnt done one in a while. Thanks again. Michael. Liked and subbed. 👍

yup finally someone speaks slow and clear.i suggest you make a video for replacing internal regulator with external one. i'm afraid my Regulator is 'integrated' and non replaceable because i can't find it it any spare part shop. (Magneti Marelli AA 125 14V 45A). i'm getting mad, my new battery drains over couple of nights, and as i turn on headlights voltage drops and gets worse and worse with stoplights, fans etc. and light dims. engine on or off no difference at all. any suggestion is much appreciated. thanks.

super quality video / information! well done. my brain just grew

Thanks for this vid, very easy to understand, no waffle. It does help that i was diagnosing this exact alternator from my AE86! found a couple of faulty diodes, so hooray, it isn't mystery wiring issues after all...

Everything word near to perfection 💯

Andy Andy I love your Explanation

Sir great narration with video such a class room like the person who don't know about alternator just spend 50 minutes is enough to understand about it Very very thanks We waiting for more video from electrical world

This video is the best one i've seen on how to test properly an alternator :) i've been having trouble with my cars alternator the first time took it apart it was very dirty inside,oil,dirt,copper and brush dust clean everything i did see the brush rings one worn out more then the other and the brushes do seem worn out enough or there is no tension in the springs that they don't make contact with the rings but after saying all that i put it back together at first it didn't want to charge but after a couple of minutes it started to charge properly but after about 10 days it failed took it apart again put it together and it charged ok but then after 2 days it failed again.

thank u Andy very usefull information you cant find easy

Well explained, I got all your points well

I am an electrical engineer. This was just what I needed to allow me to trouble shoot alternators. I had lots of AC on the armature terminal. Yup my diode were bad. Thank you Andy!

nice video sir..detail explanation..

Wow even as a lay man I got detail understanding of how to test an alternator. Thanks man.

Very well explained and well done! Enjoyed watching! Thank you !

It's my best lesson ever.....Salute teacher Thx for vital information to me

Viewing Guide: Intro 0:07 Overview of the internal components 0:35 (Stator 0:50, Rotor & slip rings 1:29, Brushes 2:22, Rectifier 2:46, Regulator 3:26) What and how we will test the components 4:53 Testing the Single Rotor winding & slip rings 7:14 Testing the Three Stator windings 12:47 Testing the Rectifier 18:23 Testing the Brushes 26:24 Testing the Regulator 27:24 Conclusion of this particular Alternator 37:32 Assumption/Alternate test method for Regulator test 38:38 & 42:44 How to properly connect the earth lead in the Regulator Test (common mistake) 39:30 Conclusion 40:20

Excellent video! Thank you!

Awesome explanation and understandable

Superb sir very nice one of the best video in the youtube. To much detail explained i never know about to test diodes. Thanx a lot.

Super Great technical video.. thank you very much..❤

Very helpful video, thank you!

Thanks! I have high resistance on one of my stator windings and some continuity from stator windings to casing, there was a buzzing sound coming from it and also a bit of burning enamel smell, battery light on, no charging from alternator when running, also noticed alternator was hot after only running for about 1 minute.

Andy, what a great video, and that without stupid useless music, so very good understandable, i always repair those myself, also new sliprings etc, bud i did not know to test the diodes on the diode mesuring of the multimeter, thanks for that.

Outstanding !!

It's Clear and very good briefing I would like to say Thank you

Thumbs up , so far this is the best i have seen. All the way from Namibia , africa 🤓

Damn, why didn't I find this video before? Anyone trying to fix an alternator needs to watch this. I'm not a professional mechanic, but I have been working on cars for friends and family for almost 30 years. Usually, I did the normal thing and replace the whole alternator if it was bad. On the car I'm working on now, a reman alternator costs about $160 locally. The whole rebuild kit is about $30. We need to get back to the old school art of repairing of parts, rather than replacing the whole part. That only serves to make the vendor more money, it isn't helping us at all.

Couldn't expect more informative video. WOW! Thanks a lot! You're doing a great job over there

very professionally done. congrats mate.

Very valuable video I sorted lots of problems thanks for your hard work.

Hey Andy, a quick on vehicle test for the voltage regulator is to vary the revs of the engine and the electrical load (switch on heaters, lights, everything) while watching the voltage output on a multimeter which should remain fairly stable. Doesn't need any fancy test gear and is a reasonable indicator if your voltage reg is working or not.

BIG THANK YOU for this great explanation and presentation sir .very precise in every detail

Thankyou best ever lesson I really understand all that. I suggest can you give a lesson on the starter motor as well. Thanks

My only criticism is I SEARCHED TOO MANY CRAP ALTERNATOR VIDEOS BEFORE I FOUND THIS!! clock-on vid thanks.

Thank you for the indepth video.