Use of a multi meter for testing the Ohms on a stator

[RRH31978]

[No message]

 

[GA_Boater]

What are you working on? A poll won't help to fix it.

What's the problem with using a meter?

 

[Texasmark]

The specs listed in the service manual are in ohms.

A 90 hp black 9-12-14 amp stator measures almost a dead short (0.1 to 0.5 ohms) between the yellow wires and open circuit yellow wire to battery - (ground). About the same resistance you would read when touching the leads together on a DMM.....since there is no zero adjust like on an analog multimeter......my lead resistance on the $6 Harbor Freight is 0.4 ohms so my reading would be between 0.5 and 0.9 ohms on the meter scale.

A 125 hp red 16 amp stator would read less ohms due to larger wire for higher current and that reading is 0.16 to 0.19 ohms. There's the range right out of the service manual.

On other sized engines the flywheel could be smaller requiring a smaller stator so I can't say just what the resistance would be, but surely similar and that you are dealing with an iron core transformer that is magnetically energized by a passing magnet imbedded in the flywheel just like the triggers are generated in a different set of coils.

 

[Dukedog]

he doesn't have a "hidden" agenda.. he's been told that tha ohms test doesn't always tell tha truth of good or bad stator... which is true!

manuals i have also give dva instructions and readings at different rpms also............

 

[Texasmark]

he doesn't have a "hidden" agenda.. he's been told that tha ohms test doesn't always tell tha truth of good or bad stator... which is true!

manuals i have also give dva instructions and readings at different rpms also............

Those readings are in amps vs rpms and can also be measured on his multimeter. Once I saw that he was seriously seeking answers to a problem, after his peculiar initial post, I redacted my statement and supplied data......an apology of sorts!

 

[dingbat]

Readings are only as good as the meter itself.

The tolerances of an inexpensive meter can be greater than the measured value

 

[Texasmark]

Readings are only as good as the meter itself.

The tolerances of an inexpensive meter can be greater than the measured value

That applies to anything. When I was in industry, we had a calibration period for every piece of test equipment which was traceable to the National Bureau of Standards.

On DMMs, I find that they are extremely accurate and since they use metal oxide resistors and computer chips, they aren't affected by environmental impacts like older technology using carbon resistors. I have a half a dozen or so sitting around the house and shop.

 

[gm280]

If anyone is really seriously trying to read such small resistances, then buy a miliohm meter. They will read in the mili-ohm range and are very accurate. It all depends on how much money you want to spend to get the accurate readings. Most people check for shorts to ground and then end to end continuity and move on. And if you are really wanting to read such things to figure out what stator you have, the meter leads shorted together is your base line regardless what meter you use. You subtract the baseline from whatever you read across the stator, and that is your resistance. Is that the accurate way, absolutely not, but it should at least get you your answer or what you are looking for

If you are really ambitious, you can even make a mili-ohm meter. There are schematic diagrams all over the net... JMHO

 

[dingbat]

That applies to anything. When I was in industry, we had a calibration period for every piece of test equipment which was traceable to the National Bureau of Standards.

On DMMs, I find that they are extremely accurate and since they use metal oxide resistors and computer chips, they aren't affected by environmental impacts like older technology using carbon resistors. I have a half a dozen or so sitting around the house and shop.

You’re showing your age...lol
NBS was changed to NIST (National Institute of Science and Technology) probably 20 years ago. Our office was just down the street from there.

While certification Is required by most quality programs, “Traceable“ (to NIST) is a joke....suggest you read up on what constitutes “traceable” in the quality world

I have a fairly expensive Fluke 87V meter. Stated resolution for resistance measurement is 0.1 ohms. Accuracy is plus or minus 0.2%.

Living in a measurement world myself, I know the advertised performance figures tell half the story.

https://www.designworldonline.com/how-to-determine-digital-multimeter-accuracy/

Then again accuracy is relative....We have customers calling in to tech support ecstatic about accuracy they are getting from our unit. Our tech guys are wondering why the unit is performing so poorly.

 

[Texasmark]

You’re showing your age...lol
NBS was changed to NIST (National Institute of Science and Technology) probably 20 years ago. Our office was just down the street from there.

While certification Is required by most quality programs, “Traceable“ (to NIST) is a joke....suggest you read up on what constitutes “traceable” in the quality world

I have a fairly expensive Fluke 87V meter. Stated resolution for resistance measurement is 0.1 ohms. Accuracy is plus or minus 0.2%.

Living in a measurement world myself, I know the advertised performance figures tell half the story.

https://www.designworldonline.com/how-to-determine-digital-multimeter-accuracy/

Then again accuracy is relative....We have customers calling in to tech support ecstatic about accuracy they are getting from our unit. Our tech guys are wondering why the unit is performing so poorly.

I didn't think you spent your life fishing for a living. Wink!

 

[Faztbullet]

All you need to test a outboard ignition/charging system is these items below:
996-170 and 996-175..analog meter with built in DVA and battery powered timing lite