Impressive demonstration of practical applications. The forerunner of this instrument is the portable, battery-powered Wheatstone Bridge with decade resistance selections. The unit was issued in the thousands to communications specialists in WWII, who used them to locate faults in telephone cables caused by battle damage. This helped save lives. I used Wheatstones beginning in the 1960s to measure thermocouple resistance and other critical circuits on aircraft. If you need to measure a very low resistance in a high-current circuit and do not have the necessary instrument, you can use a (relatively) high-current circuit, an ammeter, and a voltmeter to determine R using Ohm's Law. In effect, make your own four-wire device: Use a car battery, or batteries in series or parallel as necessary, and a resistive load, such as an old headlight or heater coil, to construct a circuit that draws current within a range you can measure with your ammeter (less than 10 amps for most DMMs). Again, you can use series or parallel connection of loads to get a usable current value. Now add the R you want to measure in series with the load and ammeter, and measure the voltage across the R while monitoring current on the ammeter. Divide the volts by the amps, and you have the R, by Ohm's Law. For instance, if the current is 8.31 amps and the voltage across R is 0.12 volts, the R is 0.0144 ohms, or 14.4 milliohms.

@WeberAuto

5 жыл бұрын

Fascinating stuff! Thank you and thanks for your feedback!

This type of low resistance meter is commonly used by professionals when testing industrial AC induction motors. Induction motors usually fail with the wire insulation shorted to the frame of the motor (ground), which would be detectable by using a megger (megaohm meter) or a hi pot meter, which places high voltage (thousands of volts) across the leads and measures the resistance to ground. Occasionally motors fail with their wire insulation not shorted to the frame, but shorted to the wire next to it. For that failure mode, the miliohm meter will show you that type of failure. To detect that type of failure you don't really need a manufacturers resistance specification because you can compare all three phases and they should be identical. If one of the three is vastly different, there is a short. Another use for this tool in the automotive environment is testing ICE vehicle starter wires and connections. A starter wire or ground may be connected, and show continuity, but be a higher resistance connection, causing voltage drop when the starter is cranking. Alternatively, if a person does not have a miliohm meter but does have a accurate milivolt meter as well as a high accuracy amp meter, and a high current DC power source, you can pass several amps through the wire or connection. Then simultaneously measure the current and voltage, and by ohms law calculate the miliohm resistance.

@WeberAuto

5 жыл бұрын

Great feedback and ideas! Thank you!

Measuring voltage drop at the fusebox is also great for finding problem circuits when looking for parasitic loads that drain down a 12volt battery to fast. Great video btw. I don't remember ever seeing anyone at work that happy to use a milli ohm meter on aircraft to check bonding when connecting two components.

@WeberAuto

5 жыл бұрын

Thank you for your feedback, I figured that type of meter was used somewhere, I had just never seen in used in automotive diagnostics before.

Wow!! Awesome explanation and presentation. The only channel in youtube where can watch hour lengthy videos without skipping any part.

@WeberAuto

5 жыл бұрын

Thank you!

Judging by your WOW expressions throughout the presentation...like a child with a new toy..."I really like it" is an understatement 24:19 ! Enjoying ones work is so rewarding! Keep up the exciting informative astonishing presentations PROF! You are truly an inspiration to learning!

@WeberAuto

5 жыл бұрын

Thank you very much! Have a great day

That was pretty cool to hear Will mentioned in your video. He is good friend of mine for over 30 years, and is why I watch your videos. And also thanks for the videos, they are a wealth of information and also fun.

4 wire resistance measurement, also called Kelvin measurement, is a awesome concept. It puts a known current through piece under test and measures the voltage through a different path. There are some good KZread videos describing it in further detail.

@WeberAuto

5 жыл бұрын

Thank you, I will check them out!

So very clearly explained, also enthusiastic, and even with a stator measurement (i want to measure my alternator stator) , thanks very much sir!

Thank you very much for your work, with the help of your video I improve my skills in car diagnostics and repair. Greetings from Ukraine!

Awesome tool. Need to start thinking about acquiring tools like this to supplement my Fluke. As an Acura master tech, IMA and EV problems are only going to get more common... Also, just wanted to say thanks for posting all the videos you do. Watching them has made me a better tech and given me a better understanding of a lot of the newer tech in cars these days. It just goes to show you never stop learning in this field!

@WeberAuto

5 жыл бұрын

Thank you very much! That is for sure, i learn something new almost every day. The industry just keeps changing.

Very neat stuff, incredible info as always. Used a cheap ohmmeter to check my nissan xterra's valve body solenoids to do a successful self repair; all local shops wanted $2200 for a valve body swap and pressured me into buying a remanned transmission instead. Found a bad lead in the valve body wiring rather than a dead solenoid using the ohmmeter, no parts needed, just a little solder job. Cost me 5 quarts of ATF and an ATF stain on my computer desk.

SALUDOS PROFE MUY BUENA EXPLICACION....GRACIAS

You're the best. Much appreciation from Tunisia.

@WeberAuto

3 жыл бұрын

Wow, thank you!

This man is a good instructor.

Have really been enjoying your videos professor, glad to see you are back. I do hope you plan on doing more Bolt videos, the Bolt battery videos are how I was introduced to this channel. Very interesting content here, keep up the excellent work.

@WeberAuto

5 жыл бұрын

Thank you! Yes, more Bolt EV videos coming in September.

Excelente explicación....nunca había oído hablar de un medidor de miliohmios y menos de su utilidad....saludos

Hioki RM3548 is a high caliber device. Thank you for this generous video ...

This thing looks cool, great vid as always Sir!

@WeberAuto

5 жыл бұрын

Thank you!

Great video! Very interesting, high precision device. Nano ohms detection sounds crazy.

Very cool diagnostics and even cooler meter. FWIW, I was a Toyota mdt circa 2009 and I recall the instructor talking about this tool at a hybrid class though we never utilized it in training. Fast forward to today and I am now a high school auto tech/cte teacher, while we would probably not use a tool like this for our regular curriculum it definitely would be a nice addition to the arsenal, there is always a handful or so of students at the h.s. level who would understand and appreciate the value of something like this, excellent content sir. You know, on edit, as I think about it, this would be a great tool if only to illustrate the value of voltage drop testing...and to discount (as you alluded to) the value of your everyday ohm meter...fascinating.

@WeberAuto

5 жыл бұрын

Great information! I think it would be a great learning tool to teach ohm’s law and relate it to real circuits. Thank you for your feedback!

Great video. We used to use milli-ohm meters when making neon signs. It helped to determine the correct size transformer to load the neon units for long life.

@WeberAuto

5 жыл бұрын

Thank you and thanks for the feedback, tht is interesting

It can be used to check switches for increased resistance as well as finding corrosion issues in places like ground terminal joints. But some of these corrosion issues can also be seen using a infrared camera (not spot measurement but using a hole picture). Since connectors are problem issues on many old cars, a comparison measurement on connecor pins can also find a corroded pin in a fast way.

@WeberAuto

5 жыл бұрын

Excellent example uses, thank you!

Wow this tool is a blessing for electronics and electrical repair.

@WeberAuto

5 жыл бұрын

Thanks for your feedback, a cool tool!

That meter is a clever piece of work. I've never seen one used before. Would be fun to add to my already crowded test bench. BUT, what really got me excited was seeing the 5ET50 stator :) Glad to see that's coming apart. I paused the video and took a screenshot of the transmission over your right shoulder to try to see if that was it. I don't think so. Waiting patiently. Thanks for doing these videos.

@WeberAuto

5 жыл бұрын

Thank you, The 5ET50 transaxle is on the far bench behind my left shoulder. The video on it will be coming in September, I have a few other things I have to finish up before school starts again in late August. Thank you for your patience.

AWSOME video. I’m learning so much from just watching these videos, I start my new job at Tesla as a technician end of April so trying to get as much on board before I start 😬

@WeberAuto

3 жыл бұрын

Good luck!

i learn allot on this video about wires and fuse

Excellent video, it would be impossible to improve your explanation about resistance and measurement of it. Thanks to your video I understand this. Thanks, teacher. Greetings from Uruguay

Great video Professor and loaded circuit testing with a mA testerand thermal imager and you could home right in on broken wire strands & corrosion. Just another tool in the diagnostic arsenal.

@WeberAuto

5 жыл бұрын

Great ideas! I have not used a thermal imager yet. Thank you and thanks for your feedback!

Great Video John ! 👍

This is marvelous

Hi Prof John. We've just used for the first time, this equipment during our Master training of Diagnostics here by Bosch Brazil. I agree with you the equipment has a high price even so for the measurements of electric and hybrid cars we notice the high level of accuracy. Additionally thanks for the tips.

@WeberAuto

3 жыл бұрын

Thank you very much

Another great video professor!!

@WeberAuto

5 жыл бұрын

Thank you!

You are great! I love your videos! Thank you Sir!

@WeberAuto

5 жыл бұрын

Thank you!

Thanks for the review. I use the 3550 Hioki battery resistance meter and i love it. very accurate for measuring cell conditions and reverse polarity protection which is good.

@WeberAuto

5 жыл бұрын

Thank you and thanks for your feedback! I will have to check it out

Professor, I don’t know how far you have gotten into the milli ohm meter but I can share a few benefits with you. I use this in the power utility field very often. 1. The best advantage in my opinion is the inherit “loading” of the circuit. That is to say a m.o.m uses a fixed very accurate current source, usually selectable(we use 10A, 50A, 100A and 200A) to cause a voltage drop across the component being tested than measured the drop to calculate the resistance. So this makes the m.o.m. Very good at finding bad connections with out having to run difficult loading voltage drop tests. It can do this quickly and very easily. Think of all the bolted H.V. Power connections to the stators and inverters. Each bolted connection and crimp and solder can be tested with out any danger or applying system current. ( Think of a bad starter cable voltage drop test on an old Ford with the solenoid on the fender, voltage looks fine till current tries to flow) 2. The 4 wire kelvin measurement allows for automatic removal of test lead resistance and test lead connections resistance. This allows you to only measure the resistance of the component under test and not any other resistances that would be in a traditional ohm meter measurement. Remember the current is fixed and the two voltage measurements are high impedance voltage measurements so the only voltage drop measured is between the two voltage leads and nothing else. 3. When you have a m.o.m. With separate current leads and voltage leads you can test a large circuit say from battery in the trunk all the way to the inverter and just by moving the voltage leads you can start to narrow down where the high resistance is along the circuit. Think of battery terminal crimp>Wire>crimp>bolted terminal>fuse blade>fuse>fuse blade>bolted terminal crimp>wire>Crimp>bolted terminal to inverter. You can push current from the battery terminal to the inverter using the current leads and probe the connections with the voltage leads taking resistance measurements of each component in the circuit. Last consideration, though the stature are small I believe using your m.o.m. On them you will be passing a DC current while testing and this with cause magnetization of the core. This could cause problems I would think with the inverter at least on initial energization of the stator. So a look at wether or not your meter offers demagnetization for after you have taken your measurement. Typically the meter goes into a process of flipping polarity of the current and lowering the amplitude to remove any magnetization of the core.

@WeberAuto

2 жыл бұрын

Awesome information. Thanks for sharing

@waynecostanza2280

2 жыл бұрын

@@WeberAuto Just looked up your meter, your meter has a 1amp max and an open circuit voltage of 5.5v ( the source for the current) so in the 3.5 Ohm and less the meter will push 1 amp of current through the component. Could use more current for the high power connections but still far better than any traditional Ohm meter.

@WeberAuto

2 жыл бұрын

@@waynecostanza2280 Thanks Wayne

@waynecostanza2280

2 жыл бұрын

@@WeberAuto Glad to give a small piece of information back for the sea of information you have provided all of us!

incredible Knowledge revealing channel

Hello . Professor John, I hope you are fine and I wish you a happy life

awesome. very educative. regards

excellent video !, was wondering how many decades would go by before the milliohm/micro-ohm meters would find their way into automotive industry, they have improved alot since we started using them in the early 1980's in the avionics industry. handy tool when used correctly.

@WeberAuto

5 жыл бұрын

Thank you, that is good to know.

Fantastic video sir!

@WeberAuto

5 жыл бұрын

Thank you!

Thanks a lot professor John. This was a great video. I always was wondering why I couldn't see any difference(ohm) in my multimeter ,when I was cutting one of the small wires on a piece of wire. I was using a wrong meter 😂😂😂😂

I bought the RM3548 for work, to measure chassis ground continuity between components as part improving EMC test results. Always ensuring 100mohms or better. Hioki has been around for a long time.

Thank you Professor- neet tool for the future of electric cars!

@WeberAuto

5 жыл бұрын

Thank you!

That is one neat tool! Should be interesting to see how quality vs cheap fuses test out.

@WeberAuto

5 жыл бұрын

Thank you!

Love ya work

13:54 - smooth edit ;) Really good video, as usual

@WeberAuto

5 жыл бұрын

Dang it! I forgot to say milli-ohm, so I pasted it in, but forgot to paste audio only! Good catch! ;) Thanks you and thanks for your feedback.

Sempre boas informações

@WeberAuto

5 жыл бұрын

Thank you!

Awesome

I've been waiting for this video and it's surpassed my expectations. Thanks Prof. Taking notes... That miliohm meter is something else. I wonder if my Fluke megger will be able to measure a 2milliohm difference.

@WeberAuto

5 жыл бұрын

Thank you, the two Mega-Ohm meters I have access to cannot measure that low. Mega-ohm meter video coming soon.

I'd agree that there is something awry with the readings obtained with the stator connections on your example Prius but the measuring point included the stator cables and their associated connections. These, imho, should be discounted before a diagnosis can be made.

The dual leads are called "Kelvin clips". Current is fed through one set of wires. It is the same inside the meter as through the unknown resistance. The other set measures voltage only. No current so there is no voltage loss and test lead resistance is removed from the measurement. From that, accurate resistance can be calculated. It can also be done using two internal brides. Look at the General Radio model 1666 which has been available for years. General Radio became "Genrad" and is now out of business.

@WeberAuto

5 жыл бұрын

Thank you and thanks for your feedback!

Very useful tool. We could use one ourselves

@WeberAuto

5 жыл бұрын

Thanks for your feedback!

the Megger MTR105 currently performs both tests and more, insulation resistance and milliohm (ohmic resistance, kelvin method).

Thanks 👍👍👍👍👍

@WeberAuto

5 жыл бұрын

Thank you!

Would be interesting to see the difference in current flow measured with a scope between the 3 phases. while driving the motor.

@WeberAuto

5 жыл бұрын

I agree, but I do not have scope leads that can handle 600V. Thanks again for your feedback

@setitthen

4 жыл бұрын

@@WeberAutoyou could get yourself a power analyzer such as: www.fluke.com/en-gb/product/electrical-testing/power-quality/435-series-ii

The 4 wire clips are called Kelvin clips.

amazing

@WeberAuto

5 жыл бұрын

Thank you!

I've got a 1587 Fluke. I'm keen to know what it can do. Planning to buy the Hioki. Its a must-have!

@WeberAuto

5 жыл бұрын

1587 Video coming soon, thanks for the feedback

keen

temperature guns and IR cameras can be very useful for diagnostics. If there's corrosion causing resistance there will be a voltage drop and heat at the bad connection. Or clean all the contact like if you have a click no crank no start. Check hardware for loose hardware.

Really great video! I am trying to wrap my head around the U W V phase wire testing on the MG motors. Are you able to explain to me why exactly will such slight resistance issues or tiny shorts create huge issues?

@WeberAuto

5 жыл бұрын

Any variance in resistance is an indication of a short circuit to another of the three phase wires or to the vehicle body. Either one will affect the amount of current available to the motor and cause the vehicle to shudder and eventually not be drive-able. Best wishes!

Powerprobe has voltage drop charts for common automotive fuses, it converts the voltage drop across the fuse into approximate current readings. I wonder how they compare to the findings using that meter!

@WeberAuto

5 жыл бұрын

I will have to check it out. Thank you!

Fascinating Vid. as always. Apple uses surface mounted zero ohm resistors in its Mac computers. See Louis Rossmann videos. I've never really understood why.

@WeberAuto

5 жыл бұрын

Thank you! Interesting, maybe they were fusistors

I have often wondered how much resistance a soldered joint has vs a crimp joint. Would love to see a comparison of the two using a mili-ohm meter.

Shorted stator can be caused from metal chips wearing into insulation. Coming on Refrigeration compressor. Solder beads floating around end up in windings

@WeberAuto

5 жыл бұрын

Great examples, thank you for sharing!

Hi professor, is it possible that your difference in resistance value on the 3 phases on your Toyota Prius stator could be done by a lost of insulation caused by moisture in the oil in the transmission case? This lost of insulation could be read also by a megaohmeter in this case? Tanks for your answer and congratulation for all your videos, you’re the best 👏

well, automotive battery (actually every kind of batteries) does have some milli ohm/micro ohm internal resistance and it does indeed dictate it's CCA capability one way or another; however it's not easily measured with such device, you'd need an AC current milliohm meter (or proper battery tester/analyzer)

based on ohm's law R=V/I, on 4 wire measurement with 0.1uOhm resolution if you provide 1 amp of current then you'd need be able to detect 0.1microvolt. Most DMM can only detect up to 0.001mv (ie. 50000 count fluke 18x or 28x series or 500000 count brymen and clones) yet their claimed accuracies dropped quite a bit at that range; you'd need a good bench desktop multimeter with 5.5 or 6 and above count for mVDC (albeit most of them nowadays sports 4W ohm measurement as well). another way is you could increase the test current to 10amp to use DMM to get 0.001mV voltage drop measurement for 0.1uOhm but it might melt those 1cm tiny cable. Micro ohm realm usually be used to measure high current contact switch, hence 10amp should pose no problem there (ie. ignition switch?, junction between fuse and its connector on electric cars pulling hundred of amps, etc.).

Nice. We have a milli-ohm meter and it’s not as accurate as yours. It’s still good. We have it for Toyota HDD training and solely for stator checks, nice to do the VD on fuses! If a tech doesn’t have access to a milli-ohm meter, if you jack up the front wheels on that Prius and rotate them, you’ll feel it’s very notchy. That’s a dead giveaway of a shorted stator, not a very common fault but we’ve seen several here in the UK. Thanks for a great video John.

@toyotatechMDT

5 жыл бұрын

Not HDD! HSD checks 👍🏻

@WeberAuto

5 жыл бұрын

Thank you. Spinning a front wheel is a great idea! I think that if there is a transmission fluid leak or the level gets set incorrectly, or the wrong fluid, the stators will not get cooled properly which can lead to eventual short circuits. Most of the hybrid transaxles I have disassembled have shown signs of running very hot. The fluid smells very burnt and a dark film is coating everything.

@WeberAuto

5 жыл бұрын

Yes, HSD. Thanks

It's certainly convenient to have this product that conveniently packages features needs for low resistance measurement, including the 4-wire measurement technique (clip-leads which have separate contancts in each jaw) and high measurement current. But you often don't need that expensive unit to do this kind of measurement. You can use a cheapie voltmeter (for example the $6 Harbor Freight, which has a 400mV scale), and a bench power supply that has a constant-current limit setting. Set the current to 1A, apply it across the circuit to be tested, and measure the voltage. Reading is 1mV per milliohm -- Ohm's law. (Or use some other creative supply of about 1A, such as say a 13 ohm 20W resistor in series with an automotive battery.) Maybe only 2 or 3 digits of accuracy, but often that's all you need.

@WeberAuto

5 жыл бұрын

Thanks for your input! The idea of having it all in one convenient package is to be able to quickly use it on a vehicle by service technician's who are typically in a big hurry. Great suggestions for alternative methods of measurements.

@Graham_Wideman

5 жыл бұрын

Oh definitely the professional tech needs it convenient to use. My cheap-o example was to illustrate that it's not doing magic to make the basic measurement, and that maybe there's a market for a meter that's significantly less-expensive by virtue of not attempting 5 digits of accuracy. On the other hand, expensive gear is nice :-)

I love finding a new tool that has great potential to open new diagnostic doors......would it be possible for you to create a video for showing the best strategy for diagnosing an electrical drivability issue like the one you described in the vehicle that had the defective stator you tested with the new ohm meter? Would stator windings be the first item to to test and eliminate in this process? And are there other things which could give the same symptons? Another inspiring video thanks prof

@WeberAuto

5 жыл бұрын

Great ideas, I will try to implement them in future videos. thank you!

At minute 21.50 you measured the voltage drop on a fuse and calculated the current based on the resistance measured in lab. But the fuse resistance was measured in another temperature environment. Also passing approx 3.6 amps, its temperature will rise, changing the resistance. I think that is a source of a quite big error. Also I wonder, can we measure the resistance in the fuse while the fuse is in operation? Or it can break the ohmmeter?

I was wondering can you use a mega ohms meter to check the windings?

Aircraft OEM is looking at .00mOhm +1 if calculated value is .00mOhm we need to read at . 000mOhm at 1 Ampere. Internal resistance to external ground must read less than 5.0mOhm. I'm not sure what electric cars require grounds should read but even then they should be as strict as AV OEM, but I don't know

nice, i use a wheat stone bridge

@WeberAuto

5 жыл бұрын

Thank you!

Normal DMM resistance measurement is quite useful for things like determining resistor values if the value marking is unreadable or determining power of a resistive heating element. They are pretty great when measuring resistances that fit in the range of normal DMM. I think the problem of measuring the two pieces of wire you demonstrated is that you are too close or under the lower limit of their range. They are great at what they are meant to do. Milli-Ohm meters are very common in electronics industry btw.

@WeberAuto

3 жыл бұрын

Thank you, yes, agreed. However, In the automotive diagnostic world, "Normal" DMMs are all that have been used for decades. As a factory training center instructor for GM and afterward in all my years of taking hundreds of training courses on other vehicle brands, a milli-Ohm meter has never been mentioned or used until Toyota introduced it a few years ago.

@fingineer2439

3 жыл бұрын

@@WeberAuto Thank you for your reply! Love your videos btw, excellent education content! I'm sure milli-ohm meters get more popular among people working with electric car motor diagnostics

👍👍

Great video, John. What is the purpose of having dual wires for each lead? Is the meter measuring the resistance of each and averaging? Also, what benefits do the hairpin style stators offer? I have not seen those before.

@WeberAuto

5 жыл бұрын

Hi Jake. One side of the alligator clips supplies a constant current through the part being measured. The other side measures the voltage drop across the same part. A pretty smart idea! The hairpin style stators are less expensive and easier to manufacturer as compared to a wire wound stator. Thanks for your feedback!

Looks like readings to tenths of a milliohm are more useful than nano ohms in the automotive sector. As such I am looking at making an add on 'matchbox' sized item to work with your Fluke 87 to provide direct FLUKE resistance readouts in milli ohms. Hopefully cost under $50. What do u think prof? BTW I have 33 years engineering exp. with M.I.T. Electronics cert. 12 years in Auto.

Sir gd am/pm sir u have idea for my display chiller actually what is correct reading for milli ohms, thank u sir for your good answer

Like a kid who got a new toy. I want that toy too now :D

@WeberAuto

5 жыл бұрын

Yes, so much fun!

@tarassu

5 жыл бұрын

Wasn't able to stop myself. Went on AliExpress and added a cheaper milliohm meter to wish list - much less capable, but it can go as low as 20mOhm scale with resolution 0.01mOhm and measuring current 100mA and no temp probe. But at least I can afford 70€ device for "domestic use" :)

Hello professor Can you do the car battery (12V ) resistance to compare good battery and some battery that is ded from junk pile? Both in the car and out the car. If it's possible.

@mondeo984

5 жыл бұрын

Can't be done. The 12V from the battery would interfear with the miliohm meters internal circuit and cause false readings. There are other techniques to measure battery resistance

@MrSerbian012

5 жыл бұрын

Ok. Please give me 2 examples how to test car battery?

@WeberAuto

5 жыл бұрын

There are tools that can quickly measure the resistance of a battery (Midtronics and Hioki make them). Old school methods will get you close using Ohm's law. Load test the battery while measuring the battery voltage and the current. Battery Resistance = Voltage / Current.

@Zener17

5 жыл бұрын

Exist one device specially designed for that BT3554 basically is the same milliohm meter and voltmeter

Very informative, do you use shorted turns testers as well? That seems like a good way to test for the same problem, and is a cheaper alternative.

@WeberAuto

3 жыл бұрын

Thank you. I am not sure what you mean by “shorted turn testers”.

@rnoid

3 жыл бұрын

@@WeberAuto There are different types, but they induce a small ac voltage into the winding, magnetically or electrically, and then determine the integrity of the windings from the measurement. www.iemmag.com/index.html en.wikipedia.org/wiki/Growler_(electrical_device) these are a few examples, but I would imagine there are ones specifically for the motors/generators in hybrids, as the principle is similar.

@WeberAuto

3 жыл бұрын

@@rnoid Thank you. I will check them out.

You can also calculate the length based on the resitance and size. l = (R*A)/ρ (0.0175 for cobber wire) So if we measure 1.4Ohm on a 6mm2 cable, it is approx l = (1.4*6)/0.0175 = 480 meters long.

@WeberAuto

5 жыл бұрын

Thank you for your feedback! Yes, it can be done with a little algebra. What is cool is that the meter can do it for you.

@kaffetrakter4174

5 жыл бұрын

Is your 1 meter testwire around 22 awg?

@WeberAuto

5 жыл бұрын

Yes it is

@kaffetrakter4174

5 жыл бұрын

Then theory and practice are equal in this case :) Handy instrument. We just use a fluke meter to measure windings on normal electric 3 phase motors out in the field.

could you use a three phase amp clamp to diagnose an stater accurately the same?

@WeberAuto

5 жыл бұрын

I have not tried that, but I suspect you could. The three-phase cables are shielded, so I am not sure there would be any signal to measure inductively. Thanks for your feedback

This is basically compression testing for electric vehicles, testing wire sets for stator and making sure they're consistent

@WeberAuto

5 жыл бұрын

True, thanks for your feedback

Professor Kelly, can you not use the Megger tester to do the same to measure the stator windings in the car?

@WeberAuto

5 жыл бұрын

Hi, If you are referring to a Mega-ohm meter, it will only measure down to 1 ohm. These windings have a normal resistance that is less than one ohm but greater than zero. It would work of there were a direct short from the windings to the stator frame, but not from winding to winding. Best wishes.

@HollywoodRoseJack

5 жыл бұрын

You said on this video you believe it has a shorted stator and the vehicle have lost of power and judders. That being said, you said here that also "these windings have a normal resistance". If it has normal resistance would it cause the symptoms of stator going bad? I'm sorry professor Kelly, I don't mean be critical.

@WeberAuto

5 жыл бұрын

Sorry for the confusion if I said that. Two of the three windings on the MG2 stator in the car were shorted. This caused the lack of power and juddering, The MG2 stator I had on the bench were not shirted and had equal normal resistance values of close to 34 milli-ohms. We installed the good stator and the car is fixed now. A car with the lack of power and juddering with good stator windings can also be caused by the inverter with shorted diodes or shorted IGBT transistors. The mega-ohm meter can be used to check the inverter for shorts with the three phase cables removed. Best wishes

@HollywoodRoseJack

5 жыл бұрын

Thank you professor Kelly for taking the time.

I need this in my life. Too bad it costs more than a grand. Very awesome tool

@WeberAuto

5 жыл бұрын

I agree! Pricey, but cool!

@w5cdt

4 жыл бұрын

See my comment above...

shorts in MG2 likely cause by engine vibration rubbing off insulation or breaking a cold weld.

bro,,, we gottsta have sake....one day... this exactly my headache... wires ,, test leads etc

Editor and reader lol never heard of that milli ohm meter. What's next, a micro ohm meter? 😆 thank you for sharing professor 👍

@WeberAuto

5 жыл бұрын

Thank you! This Meter does measure micro-ohms with a resolution of 100 nano-ohms, incredible!

@SuperMarioDiagnostics

5 жыл бұрын

WeberAuto wow i am eating my words lol talk about accuracy, if only we had dc ammeters with similar resolution of 100 nano amps. I bet in the future we may have to deal with such small current(cpu circuitry). I learn something with each one of your videos. Thank you!

very nice explain professor nice tool, question not relevant to meter , what software you use to edit the videos to add second screen?? thankyou have nice day one again thank you for sharing valuable training.

@WeberAuto

5 жыл бұрын

Thank you! I use Apple Final Cut Pro. You can add up to 7 additional screens.

Hi does any body know if the video about mega and gega ohms insulation testing video is available

@WeberAuto

3 жыл бұрын

Right here kzread.info/dash/bejne/YmSZp8yYdcqzkdY.html

@jasbierkandola5736

3 жыл бұрын

Big thank you and what a great channel and fantastic content 👍🏽

@WeberAuto

3 жыл бұрын

@@jasbierkandola5736 Thank you

Thanks for sharing another great video! Did you work in the electric field before you became a Professor ? Please put me in for the "give away" of the incredible milli-ohm meter. :)

@WeberAuto

5 жыл бұрын

Thank you, my undergraduate degree is in electronic engineering technology, but I have always been in the automotive repair or education industry. Nice try on a give away, I will be doing good just to buy one for our shop.

If you have 20 strands and you cut one, the resistance should become 20/19 times the value before you cut. If you have 3 strands and cut one, the resistance should become 3/2 times the values before you cut. So each time you cut, the absolute increase of resistance will vary (increase).

The meter is a Wheatstone bridge

I wonder what increases the ev range on evs, the higher amperage or higher voltage?

@WeberAuto

5 жыл бұрын

A combination of both over time, Watt Hours.

@fix-and-drive-diy-repairs

5 жыл бұрын

@@WeberAuto thank you professor.

When you explain how a 9 speed transmission use one input shaft and how it shift. I didn't think you could top that. I'm making a video on my channel about this. I don't think no one will understand me or why they should care.

@WeberAuto

5 жыл бұрын

Thank you very much!

Cambridge med instruments made micro amps meters to test under 10 micro amps some 30 years ago.

I have BK 2840 DC Resistance Meter

@WeberAuto

5 жыл бұрын

Looks like a nice bench meter