Alternator Component Testing

[@CarbonGlassMan]

This video is a great help. Thank you for making it. I will not pay $250 for an alternator for a 2005 Colorado with 263k miles on it unless I have to. My alternator stopped charging so with this video I was able to check for continuity in the field coil (good), the 3 phases of the stator (good) and the diodes (good). I noticed one of the diodes came loose from the rectifier. I soldered that back together and replaced the voltage regulator. That did not fix the problem. The slip ring was very deeply grooved and one of the brushes was very short. The slip ring connection to the field coil on my alternator was covered in a thick epoxy so I was not able to test those connections until I had chiseled the epoxy off the connection, so I may have broken a connection when chipping the epoxy off, but one of the slip rings did not have continuity, so I am hoping that the problem was with a connection to the slip ring. Luckily the rebuild kit I paid $47 for included bearings, a voltage regulator and a new slip ring. I hope tomorrow when I replace the bearings and the slip ring that my alternator will start working again.

[@PetarMakTeacher]

The excessive wear of the slip ring and brushes may be due to oil contamination. I have repaired many alternators by replacing brushes and slip ring, be aware that some new slip rings will need machining after fitting. Good luck with your repair.

[@ShakirAuto067]

Good bro

[@CarbonGlassMan]

@@PetarMakTeacher my rebuild kit fixed it.

[@MasoudMehdirad]

Perfect and straight forward. Thank you. Well done.

[@martinez1701a]

Great video, with how expensive these alternators are today it's good to know how to test individual components and save money on repairs.

[@ShakirAuto067]

Nice bro

[@JerichoRally]

Phenomenal demonstration! Thank you very much!

[@ShakirAuto067]

Yes bro

[@pragasamsupiahs8419]

Very clear and concise explanation on the workings of an alternator. Thanks for the video sir.

[@ShakirAuto067]

Nice bro

[@mouldyboats]

Reversing polarity during Diode test IS part of a diode test that should be done. After all it tests the primary function of the diode (rectification)

[@JerichoRally]

Excellent point. Diode is akin to a check valve in plumbing. It should only allow current to flow in one direction.

[@shamolshahran1570]

Been searching for a good video on this topic. And in My opinion this is one of the best on you tube. Thanks you very much. Subscribed.

[@ShakirAuto067]

Nice bro

[@billionkitchensbillionkitc5504]

Thanks for the first time to see rotor test

[@ShakirAuto067]

Nice bro

[@samsonhetz]

Thanks 👍👍 this is very clear and easy to understand.

[@machineman6498]

Thank you for making this

[@fransmosia5880]

Thank you sir this is a very good video, you made me understand the fundamental operation of an alternator in 14 minutes.

[@ShakirAuto067]

Nice bro

[@savioursaili40]

This is very good and clear

[@SunilSingh-vg3kz]

Thanks man I really learnt alot

[@clementmoves9704]

So good of an explanation!

[@ShakirAuto067]

Nice bro

[@user-uo1em5qn3g]

I really like your video sir Its is really informing Thank you Keep going

[@busterscruggs3031]

awesome video, as a student I really appreciate the knowledge. thanks

[@ShakirAuto067]

Good bro

[@solomonmapfumo3150]

Well explained thank you sir

[@samg5543]

Excellent info. Thanks

[@jeremycalnan4180]

I like how he keeps flipping me off

[@jon-7-9]

Awesome

[@tafadzwanormanmanzungu6110]

Thank you 👏

[@PaulR387]

Very good video thank you

[@yuusuffaandhe509]

Yes i need lots of differetial works of an alternator

[@vivekindia9000]

Fantastic and good explanation Thank you

[@ShakirAuto067]

Good bro

[@radishpea6615]

Great video. The measurements/readings you got for the various components, how well can we use them for our own alternators? Do the measurements differ much if at all between smart and dumb (always charging) alternators?

[@PetarMakTeacher]

The basic components of the alternator are the same. The difference with the smart alternators is the type of regulator. Some new alternators do not have a regulator, the control is performed usually in the body control module of the vehicle.

[@radishpea6615]

@@PetarMakTeacher cheers

[@realjiver2]

Tests showed nothing wrong BUT Amp Clamp showed battery drain 0.34 amps back through alternator. Changed rectifier and no more drain.

[@ShakirAuto067]

Good working sir 😊

[@user-hd8op7tb3u]

Hi there, can anyone tell me, I did this test and found the voltage regulator testing faulty, would this be the reason when I connect the battery to the cable that connects to the alternator this cable becomes very hot at the alternator end,

[@PetarMakTeacher]

This sounds like quite a problem. It could be a few different things causing it; the most likely are either the battery polarity is incorrect, or the alternator has an internal short circuit. Either of those options is serious and should be fixed immediately.

[@ShakirAuto067]

Nice

[@henrythokozanindlovu8451]

Wow

[@ruylorenzoperez5616]

thank you sir...

[@kaapuutt]

Excellent man u should be a professor, even the dumbest person can understand 👍👍👍

[@thedolphin5428]

Serious Question: Balmar alternators (which I don't have) have a "Stator Monitoring Wire" going to their external regulator (which I do have, an MC-618 on my boat connected to a generic alternator). To add this wire, onto which internal stator connection point should I attach it? I am presuming ANY ONE of the 3 delta points, thus telling the external regulator sensing circuit that the stator is either at ground or open circuit despite field being fed to the armature. A stator failure would therefore signal a different error code to that of a failed bridge rectifier, ie a charged stator but with no B+ output.

[@PetarMakTeacher]

I'm not familiar with the alternator you mention. Some of the car alternators use a stator connection which indicates to the regulator that the rotor is spinning, and it will begin supplying rotor current, even if there is no warning lamp circuit connected. It may be similar, however some of the external regulators used a star point connection to operate the warning lamp. If this is the case, the delta voltage connection may be too high if the regulator requires a star point connection. You will need to find more information from the original manufacturer.

[@thedolphin5428]

@@PetarMakTeacher Thanks. But I have since figured the matter out. Fyi, the "W Connection", also called the "Windings Connection, Tacho Sense Wire, or Stator Output Wire" is connected directly to ANY ONE of the three AC stator points (delta or star config), prior to the rectifier bridge. This gives a reading of only 3-10 Vac and of a varying frequency to indicate alternator RPM to a tacho which then divides it down for engine crank RPM. The W wire is not the same as a warning lamp connection (L), which is a DC link to the ignition lamp (rectified by the smaller diode set, where provided) and which is also used (in "single wire alternators") to self-excite the alternator.

[@TheDowden6]

Thanks for the video. What happens if the overall diode test results in a measurement above 800 mv? My Hitachi 110 amp alternator is having charging issues and the diode test is measuring around 827. Thanks.

[@TheDowden6]

Here are a few more details. When I measure each of the 8 individual diodes, they are all around 490 mv. When I measure from the b+ post to negative diode plate, I get around 1220 mv. When I measure from b+ post to one of the posts on the voltage regulator, I get around 820 mv. From the negative diode plate to the same post on the voltage regulator, 1662 mv. From these inconsistent readings, it would seem I need to replace the diodes along with the voltage regulator. These two pieces are riveted together so it appears they are meant to replaced as one unit.

[@PetarMakTeacher]

@@TheDowden6 When testing the diodes it is best to test them individually. If the stator is connected, the circuit through the windings will affect the readings. There is a variation of voltage levels between diodes from different alternators, but when testing diodes within one alternator they should have the same reading as each other.

[@stevedooley-zq3qp]

U have found your calling wish all videos were that easy to follow. When doing the last test on the rotor i cant get it to read OT it reads 1.860M does this mean its buggered thanks in advance

[@PetarMakTeacher]

1.8M Ohms to the ground is ok. It may be a small amount of carbon from the brushes or moisture.

[@user-qj3rv2mo1b]

The direction of the current alternates because the connection of the router leads with stator leads alternates after each 180 turn of the router through the two slip rings?

[@johngilligan9305]

No. the pre-rectifier current alternates because the magnetized Rotor has North & South polarity passing through the Stator windings, generating AC current

[@silveriosoloveres1716]

sir kindly explain how test brushless alternator

[@PetarMakTeacher]

The components in brushless alternators are the same as brush type (except of course they don't have brushes). An iron cage spins around the fixed electromagnet to supply the changing magnetic field.

[@tommydscott]

You should keep your fingers off the probes when testing.

[@dinuka7932]

Sir where is the voltage regulator

[@thedolphin5428]

An alternator's voltage regulator can be internal or external. If internal, it is a small, sealed, unserviceable item on the diode plate. If external, it can be a coil and contacter box, a solid state unit, or done by the ECU (the car's computer).