Electrical test meters,,,got one ?

[kebo]

Agreed. All we really require is a meter that only does DC volt's and ohm's to the tenth. EI; 00.0V

What more do we need ?

Well, for most of the stuff in the house you need one that reads AC volts. Fortunately, most every DVM made now does both AC & DC measurements.

For resistance measurements, you sometimes need good resolution when trying to trace down true dead shorts. In those cases, the more digits you have to the right of the decimal, the better. But probably not too often you actually need that extra resolution doing the normal electrical debugging on most equipment. I have a Fluke bench top meter with a batteries inside, so it is a portable unit.

 

[jenkinsph]

I have Fluke test equipment and have had good service from it. For most simple trouble shooting almost anything will work, most people can get by with an inexpensive dvm at home. Fluke does make a nice little meter that will display voltage ac/dc, ohms and has a 100amp current clamp for less than $100, good for most stuff on a homestead.

 

[BobRip]

I have Fluke test equipment and have had good service from it. For most simple trouble shooting almost anything will work, most people can get by with an inexpensive dvm at home. Fluke does make a nice little meter that will display voltage ac/dc, ohms and has a 100amp current clamp for less than $100, good for most stuff on a homestead.

Just don't get the one that does not measure DC VOLTAGE. A cheap meter is 1000 times better than no meter and for most people it's enough. An an expensive meter is even better.

 

[SPYDERLK]

Darn right! ... Tho, other than as a sorta gross contact indicator, Ohm scales are often pretty worthless .. and dangerous to the meter. [The live circuit mistake mentioned in posts above.] Also contact resistance can skew a sensitive Ohm reading by a large proportion. b-u-u-t:

Getting a handle on Ohms law and the use of a digital voltmeter to assess current flow and voltage drops in a circuit will help you in all electrical trouble shooting. For instance, if you have a DVM, put the leads across a battery conection - one to the batt terminal - the other to the clamp on the batt cable. What you have done here is essentially short the meter leads together, but not quite - there is a very low resistance at the crossover between the batt and clamp. Now set your meter to its most sensitive DC Volt scale - probably 200 millivolts. Typically these meters, on this scale, will resolve down to one tenth of a millivolt -- [0.0001Volt !] Since the leads are "shorted" the meter will read zero. Now turn on your lights. The connection you are measuring across will now be carrying current. Its [hopefully] verry small resistance will result in a voltage across the connection. This voltage will be the current (I) drawn by the lights X the resistance [R] across the connection. To use round ballpark numbers: 5A for the lights and about 0.001 Ohms for the connection. You meter will read 5.0 millivolts - Ohms law is being obeyed. By the equation V=IR you only need 2 of these numbers to "derive" the third. -- So, without knowing the quality of that battery connection you can determine it by measurement. -- Say you know the lights on your tractor draw only 5A and the reading you take with the DVM is 20.3mV across the battery connection with the lights ON. Then, scrambling the equation: R= 0.0203V/5A= 0.00406 Ohms. For a BATTERY connection this is terrible quality. When you draw 200A to crank your engine that meter is going to read V=200x.004= 812mV [youll have to go to a higher scale]. The starter needs this [lost]voltage. Youll notice slow cranking and the connection will get hot. You meter and Ohms law tells you so.
--- The same idea can be applied to any connection or length of wire in a circuit that is carrying current. There is always a voltage loss, and a sensitive meter will asses it. Even the $5 HF DVM is sufficient.
larry

 

[jenkinsph]

Just don't get the one that does not measure DC VOLTAGE. A cheap meter is 1000 times better than no meter and for most people it's enough. An an expensive meter is even better.

My concern with something overly cheap would be the insulation properties of the meter and leads. Some of the real el cheapo stuff might be okay working around a 12vdc system but at higher voltages I would be skeered to use them. I should have posted the small Fluke meter I recommend is the T5-600. I keep one of these in each of my trucks for everyday use. This saves wear and tear on the more expensive equipment I want to preserve.

 

[flyerdan]

Have to agree that a DMM is a required resource for any serious troubleshooting. I've got a couple of the earlier versions of these, had one at work and one at home. One thing I quickly found is that it helps to make at least one additional lead with an alligator clip on it so you don't run out of hands on those long reaches.

 

[BobRip]

My concern with something overly cheap would be the insulation properties of the meter and leads. Some of the real el cheapo stuff might be okay working around a 12vdc system but at higher voltages I would be skeered to use them. I should have posted the small Fluke meter I recommend is the T5-600. I keep one of these in each of my trucks for everyday use. This saves wear and tear on the more expensive equipment I want to preserve.

It's not just the insulation. But the fusing. The cheap units can explode if subjected to high voltage with high power available. Use on a car is fine.

 

[rsewill]

If not, why not ?
...
If ya don't know how to use one

Yup, my problem. And my father and brother are electricians. Which may explain why I never learned how to use one because I can always call them for troubleshooting instructions. They'll talk me through any testing. Makes me lazy to learn because all I want to do is fix the problem.

 

[BobRip]

Darn right! ... Tho, other than as a sorta gross contact indicator, Ohm scales are often pretty worthless .. and dangerous to the meter. [The live circuit mistake mentioned in posts above.] Also contact resistance can skew a sensitive Ohm reading by a large proportion. b-u-u-t:

Getting a handle on Ohms law and the use of a digital voltmeter to assess current flow and voltage drops in a circuit will help you in all electrical trouble shooting. For instance, if you have a DVM, put the leads across a battery conection - one to the batt terminal - the other to the clamp on the batt cable. What you have done here is essentially short the meter leads together, but not quite - there is a very low resistance at the crossover between the batt and clamp. Now set your meter to its most sensitive DC Volt scale - probably 200 millivolts. Typically these meters, on this scale, will resolve down to one tenth of a millivolt -- [0.0001Volt !] Since the leads are "shorted" the meter will read zero. Now turn on your lights. The connection you are measuring across will now be carrying current. Its [hopefully] verry small resistance will result in a voltage across the connection. This voltage will be the current (I) drawn by the lights X the resistance [R] across the connection. To use round ballpark numbers: 5A for the lights and about 0.001 Ohms for the connection. You meter will read 5.0 millivolts - Ohms law is being obeyed. By the equation V=IR you only need 2 of these numbers to "derive" the third. -- So, without knowing the quality of that battery connection you can determine it by measurement. -- Say you know the lights on your tractor draw only 5A and the reading you take with the DVM is 20.3mV across the battery connection with the lights ON. Then, scrambling the equation: R= 0.0203V/5A= 0.00406 Ohms. For a BATTERY connection this is terrible quality. When you draw 200A to crank your engine that meter is going to read V=200x.004= 812mV [youll have to go to a higher scale]. The starter needs this [lost]voltage. Youll notice slow cranking and the connection will get hot. You meter and Ohms law tells you so.
--- The same idea can be applied to any connection or length of wire in a circuit that is carrying current. There is always a voltage loss, and a sensitive meter will asses it. Even the $5 HF DVM is sufficient.
larry

This is an excellent technique. Ideally suited to no crank issues. I also recommend to test battery voltage when cranking to test the battery. Put your probes right on the battery post. It should have a low when cranking of greater than 10.5 volts for a good battery. Many engines will crank at lower voltage, but if you get below 6 volts, you need to recharge. Fully charge the battery and then crank test again. If this does not help it is probably time to replace the battery.

 

[k0ua]

I have several digital meters, from HF ones on up to good ones, and one old but still good Analog meter I have had since age 13 ( a lot of years ago).. the digital's are best for diagnosing battery/connection problems due to their resolution and accuracy and the analog is best for checking semiconductors and capacitors. As in your motor start/run Caps. Yep everyone needs at least one good meter, but I like to have several of different grades depending on what and where I am working (outside in the rain, or on the bench)

James K0UA