Measuring voltage from RCR123 cells with DMM

I searched and found several threads that had some relevance to my question but didn't answer the simple question of what setting to set the DMM at to get a voltage reading. I did get a reading of 4.03 whatever trying different settings I believe was 9v but I think I also had my finger under the black negative probe. Now that same setting shows zeros.

I went through HJK's guide and he compares a Fluke meter to a BEST (cheaper generic) meter. Odd I see the red probe being used as negative and black as positive. Never in my wildest dreams would I even have tried that as any electronic device I have be it a car battery to guitar pedals the black lead is always negative. Also on his direct comparisons some of the readings weren't off by .01 or but the numbers didn't even appear to be measuring the same thing.

I have a middle of the road DMM I think I spent $50 at Radio Shack several years ago. I mainly use it for measuring resistance in guitar pickups and testing voltage of AA/AAA primary cells as there is a dedicated AA/AAA position.

Put the black test lead plug into the COM port on the meter. Put the red test lead plug on the V/Ohm port. Make sure you aren't plugged into the AMP measuring ports on the DMM.

The "9V" range is probably a 9V battery tester range and should not be used for this test. (similar to that "AA/AAA test section) If your DMM has settings for battery testing ignore them (this will often be listed as a 1.5V, 6V, 9V, 12V options that are off in a different "zone" than the normal voltage meter). (These "battery test" functions on multi-meters often apply a load to the cell and then determine the condition of the cell based on the voltage it maintains under that load).

There are many different styles of multi-meters out there. Some will require manual selection of ranges, others are auto-ranging. Most meters will have a 20V DC range, this is what you should be using. The state of charge of a li-ion cell is directly related to the voltage it is resting at. No load is required to determine the state of charge, so there is no need or reason to use a "battery test" function on a DMM. Besides, the load it would present and the results it would generate would not be relevant since the test is designed around the behavior of a typical 9V alkaline battery (when using the "9V" test option.)

When measuring voltage, there is nothing wrong with connecting the DMM to the battery backwards, the DMM will simply show a negative voltage instead of a positive voltage but the absolute value remains the same either way.

Eric

Beacon of Light said:

I went through HJK's guide and he compares a Fluke meter to a BEST (cheaper generic) meter. Odd I see the red probe being used as negative and black as positive. Never in my wildest dreams would I even have tried that as any electronic device I have be it a car battery to guitar pedals the black lead is always negative. Also on his direct comparisons some of the readings weren't off by .01 or but the numbers didn't even appear to be measuring the same thing.

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I do not compare a Fluke to a BEST, I show how to use two different meters: A top of the range and a very cheap meter. I hope that showing examples with these two very different meters, makes it possible for people to deduce how other meters are used.

The only place where I switch red/black is the notes at the bottom, and I do it to explain that a modern DMM does not care about plus/minus on most ranges.

Black is not always the most negative voltage, but is usual the reference plane (called gnd or ground), some equipment requires both positive and negative voltage from the reference plane.

Mostly the two meters shows close to the same value, just remember that the Fluke has more digits. The exception is current, there the cheap meter has a problem with the pulsing current that the flashlight uses.

You are welcome to ask specific questions in the thread about the guide or how to do other measurements.

Ok, tell me what I am doing wrong please. There is no 20 volt range listed per se, unless one of those symbols means 20 volts. This is an auto range DMM so it makes me scratch my head why something theoretically this simple seems impossible here and I'm not exactly a noob to electronics at all.

Beacon of Light said:

Ok, tell me what I am doing wrong please. There is no 20 volt range listed per se, unless one of those symbols means 20 volts. This is an auto range DMM so it makes me scratch my head why something theoretically this simple seems impossible here and I'm not exactly a noob to electronics at all.

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I would expect it to be auto range, but I do not know it. Usual auto range meters will change to manual range first time the range button is pressed, further presses on the range button will change range.

Look at the display it shows a ~ symbol, this means that the meter is measuring AC. A battery is DC (Symbol is probably =, but the lower line might be dashes), try pressing the yellow button.

It is auto-range and there is a way to disable that and set the range manually. To keep this simple I left it at auto. When I press the SELECT button the ~ symbol disappears and then without the probe connected to anything the meter starts counting incrementally. What the hell is that? While the numbers are still counting up I test the battery and nothing changes. This shouldn't be this difficult.

Beacon of Light said:

It is auto-range and there is a way to disable that and set the range manually. To keep this simple I left it at auto. When I press the SELECT button the ~ symbol disappears and then without the probe connected to anything the meter starts counting incrementally. What the hell is that? While the numbers are still counting up I test the battery and nothing changes. This shouldn't be this difficult.

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I agree that it should not be this difficult. If you have some spare batteries laying around, try replacing the batteries in the meter.
Other than that, I do not have any ideas what it wrong (Except the meter might be broken).

Looks like he hold button might be activated, turn it off if it's on.

Use a combination of the range button and select button to cycle through modes and options. You might also try with a DIFFERENT power source, like an alkaline battery or something just to rule out the possibility that the PCB on the cell hasn't cut the circuit for some reason.

Eric

try testing a known good battery like a AA alkaline on the V scale and see if you can get a reading ~1.5v or so. This will show you if the meter is operating properly. If it does work then the other battery must have problems otherwise your meter may be broken (may need the fuse replaced due to testing batteries on the A (amps) scale)

mdocod said:

When measuring voltage, there is nothing wrong with connecting the DMM to the battery backwards, the DMM will simply show a negative voltage instead of a positive voltage but the absolute value remains the same either way.

Eric

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right unless it is an Analog meter with needle that moves up and down. then you "pin" the needle and wonder why it reads all wrong after that

the 9v setting should read a Li-ion ...

Having said that , where is the instruction manual ?

It looks like once you select V , you then have to push the Range button to select the voltage range , yeah , guessing here ..

Two interesting buttons , select and range

Strongly urge you to read the instructions , if you get a reading on the 9v setting , its probably true .. [It should work] .

Beacon of Light said:

but I think I also had my finger under the black negative probe. Now that same setting shows zeros.

. . .

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protected cell item, is it charged ? will it run something? protection disconnects the battery when the voltage of the battery is too low (and to high but that should allow for a drain still) The curcuit in there helping the cell, doesnt always help trying to figure out what the heck is going on

VidPro said:

protected cell item, is it charged ? will it run something? protection disconnects the battery when the voltage of the battery is too low (and to high but that should allow for a drain still) The curcuit in there helping the cell, doesnt always help trying to figure out what the heck is going on

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yes protected cell and it works fine in my Novatac. Heck at this point I should just buy a Liteflux LF3XT just to use the voltage reading it has built in. Pretty much how I text my AAAs in my LF2XT. Yay another $60 for a light I don't need.

old4570 said:

the 9v setting should read a Li-ion ...

Having said that , where is the instruction manual ?

It looks like once you select V , you then have to push the Range button to select the voltage range , yeah , guessing here ..

Two interesting buttons , select and range

Strongly urge you to read the instructions , if you get a reading on the 9v setting , its probably true .. [It should work] .

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I probably bought this back in 2000 maybe before that even. No clue if it ever came with a manual other than a small folded reference sheet since it came in a plastic shell and I don't ever recall a book coming with it. I'll look if they have a PDF of it online, but I doubt it.

Beacon of Light said:

yes protected cell and it works fine in my Novatac. .

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so i dont confuse, right after you pulled it out of something it was STILL working in, you should be able to get a reading, the protection curcuit does not always keep you from getting a reading. and i might have infered that. It can keep you from getting a reading when the battery is to low.

Lynx_Arc said:

try testing a known good battery like a AA alkaline on the V scale and see if you can get a reading ~1.5v or so. This will show you if the meter is operating properly. If it does work then the other battery must have problems otherwise your meter may be broken (may need the fuse replaced due to testing batteries on the A (amps) scale)

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no reading just zeros. This just worked yesterday as I was testing AAs and 9v batteries. Crap did testing this RCR123 blow up my meter?

Beacon of Light said:

no reading just zeros. This just worked yesterday as I was testing AAs and 9v batteries. Crap did testing this RCR123 blow up my meter?

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mabey you just blew the fuse? this time. it wouldnt be uncommon.

What exactly causes a fuse to get blown checking battery voltage?

Beacon of Light said:

What exactly causes a fuse to get blown checking battery voltage?

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being on the ma setting, or switching past that setting while connected to the wrong things , across batteries, in wall plugs hey dont ask .
the fuse on the small side (my words) is very low amperage and fast blowing, so a person doesnt toast the highly sensitive side of the meter.

opened up the DMM and there was a spare fuse. ARe they supposed to be white, I'm used to seeing fuses with a clear glass with a wire filiment thing and when it is blown you see the metal twisted, black and disconnected. This looks like a white powder is inside. Weird the spare would be blown as I have never opened up the DMM before. I am assuming it is blown as I tried both of them and now the DMM doesn't even power up. What the hell???