Thread: Simple guide to using a DMM for measurements

1. Re: Simple guide to using a DMM for measurements

"To get a better idea about how it will work in a flashlight, I need a load on the battery, here I am using a 1ohm resistor. The battery still maintains voltage enough to drive a flashlight. The resistor must be at least 3 watt, but a resistor rated for a higher wattage (i.e. 10 watt) is much better, because it will stay cool.

Next battery is a LiIon 18650 battery, this requires the 20V range, the battery has 4.17 volt. For a LiIon this means that it just about fully charged. The voltages for a LiIon must be measured without load and are: Fully charged 4.2V, empty 3.6V
When getting a new LiIon charger it can be a good idea to check the voltage, on the cells, when they are removed from the charger, they must not be above 4.3V, it is much better if they are at 4.2V."

Hi HKJ,
Could I ask why a LiIon must be measured without load whereas an Alkaline or NiMH needs to be measured with load in order to gauge the energy level of the battery? What happens if you measure a LiIon with load?
Thanks.

2. Re: Simple guide to using a DMM for measurements

Originally Posted by Planz
Hi HKJ,
Could I ask why a LiIon must be measured without load whereas an Alkaline or NiMH needs to be measured with load in order to gauge the energy level of the battery? What happens if you measure a LiIon with load?
You can measure LiIon with load, but the tables listing how much energy is remaining will not be correct.
Measuring Alkaline or NiMH without load will show them as nearly full, even if they are close to empty.

3. Re: Simple guide to using a DMM for measurements

Got it. Thanks!

4. Re: Simple guide to using a DMM for measurements

Wanted to say thanks for this guide and let HKJ know some of us are using it.

A few years ago this was the first guide I saw to show me how to check voltage on my cells. Little did I know how frequently I would be doing this the more I got into things. I have also diagnosed two bad McClicky switches with the tailcap part of the guide; one of them just today. Good stuff.

5. Re: Simple guide to using a DMM for measurements

I agree wholeheartedly! It is a great resource, and Henrik is a great member! Thank you.

6. Re: Simple guide to using a DMM for measurements

Originally Posted by OneBigDay
A few years ago this was the first guide I saw to show me how to check voltage on my cells. Little did I know how frequently I would be doing this the more I got into things. I have also diagnosed two bad McClicky switches with the tailcap part of the guide; one of them just today. Good stuff.
I am in the process of monitoring battery aging by measuring their Internal Resistance.
Another thumb up for HKJ

7. Re: Simple guide to using a DMM for measurements

Originally Posted by kosPap
I am in the process of monitoring battery aging by measuring their Internal Resistance.
Did you see my writing about that: http://lygte-info.dk/info/Internal%2...ance%20UK.html

8. Re: Simple guide to using a DMM for measurements

Yes i did...And if i hadn't , i would never sit down and do it.....
It has opened my eyes on how my 18650s age and helped me avoid a 4x battery combiantion that one 18650 had increased resistance (some batteries, rarely used, but with 1 year difference in production lot)

BTW I am using the "first" method, with a resistor that matches real life current draw at max output

9. Re: Simple guide to using a DMM for measurements

Just the info that I was looking for...thanks a lot.

10. Re: Simple guide to using a DMM for measurements

Originally Posted by HKJ
I often use a Fluke 179 DMM for various tasks, but for just checking batteries it is way to expensive, a Fluke 115 would do for that. The 115 has a 6000 scale, i.e. you will get battery voltage with 3 decimal digits, but the DMM is missing the low current ranges and cannot be used to measure low modes current draw and standby current with.
I'll vouch for the Fluke 115 as being the least expensive multimeter you can trust out of the box. Or perhaps the 114 if you don't do any sort of current measuring with it. While the 115 doesn't have a milliamp range, it will measure below 1A, but the cutoff seems to be about 100ma. So it is not ideal for testing very low currents like you mentioned, and if you test led's, may not have enough voltage to light them brightly. It is after all an an electrician's meter, not an electronics oriented one. For that kind of use my 87V is brought out.

Most importantly, the min-max function, which also beeps audibly at changes of 1mv, has a very important function when working with li-ion. When a cell that is under discharge or charge, when you hit the steep charge/discharge knees, the meter starts to beep very fast - important for safety in case something goes wrong. You can also use it to know if you have suddenly dropped a cell, or if a cell that seems normal just goes berserk. With the audible beeps, you can catch this activity before it goes to the extremes. The beeps on the 11x series are a bit lower than say an 87V, as the piezo beeper is much smaller.

Also not mentioned about using cheap meters is their measuring speed, and some tendency for over and undershoot. The Flukes are plenty fast and are bang-on without nary an under or overshoot.

For me, working on li-ion without a quality meter is just asking for trouble. I also vote for HKJ's wonderful work to be a sticky!

11. Re: Simple guide to using a DMM for measurements

Originally Posted by mbiraman
Great job HKJ. I was wondering . On the ZTS battery tester under 3.6v you see listed a number of batteries but not 14500. My aw 14500's are 3.7. Does it matter ?? . Can the 14500's be tested in the 3.6 spot??
Originally Posted by HKJ
Yes, it can, it is about the same as RCR123A/16340.
I was reading the LiIon Battery tester section, and saw that you were using the ZTS MBT-1. I have the ZTS MINI-MBT, and it has the same 3.6V Lithium-Ion RCR123A, 18500, 17650 terminal for 14500 batteries. I was reading BU-409: Charging Lithium-ion - Over-discharging Lithium-ion: "Li-ion should never be discharged too low..."

Which percentage on the ZTS should be used for when it's time to charge a 14500 LiIon?

12. Re: Simple guide to using a DMM for measurements

Originally Posted by 5S8Zh5
I was reading the LiIon Battery tester section, and saw that you were using the ZTS MBT-1. I have the ZTS MINI-MBT, and it has the same 3.6V Lithium-Ion RCR123A, 18500, 17650 terminal for 14500 batteries. I was reading BU-409: Charging Lithium-ion - Over-discharging Lithium-ion: "Li-ion should never be discharged too low..."

Which percentage on the ZTS should be used for when it's time to charge a 14500 LiIon?
I have not checked it but 0% or 20%. I will expect 0% to signal empty, but not necessary over discharged.

13. Re: Simple guide to using a DMM for measurements

Originally Posted by HKJ
I have not checked it but 0% or 20%. I will expect 0% to signal empty, but not necessary over discharged.
Thanks. ...

14. Simple guide to using a DMM for measurements

Hi CPF & HKJ,
I have been using a DMM for years, thanks to learning of the importance of matching in multi-cell lights from CPF. I recently added a ZTS to measure load. Because I have an extensive collection of lights and rotate their use, I have a maintenance schedule for all lights to have threads & O rings lubed, a quick polish with a protectant and I check the cells. I have over 20 Surefire multicell lights and when testing I was shocked to find Surefire CR123A cells that measured 3.16 V on both cells but under load testing with the ZTS they only showed 20% capacity. This occurred on 3 different lights. A fourth light measured 3.12v on both cells but under load 1 cell was 20% and the other 60%. The remaining lights were all above 3.0v with 100% on load testing. I repeated all tests multiple times to rule out poor contact. None of the batteries are more than 3 years old. Any idea why the voltage would be good but under load fail? Am I correct in assuming these batteries should be moved to my Surefire Hurricane lamp or Joule thief since their runtime could leave me stranded? Thanks for any information you can provide.

15. Re: Simple guide to using a DMM for measurements

Hello Crazyeddiethefirst,

If you are up for an experiment...

Test your low cells and note the ZTS value associated with each cell that is in question.

Take a cell that showed low capacity on the ZTS and put it into a single cell light that draws reasonable current. If you don't have any, pick two of the cells that showed low capacity and put them into a multi cell light.

Next turn the light on for 15 - 30 seconds, then shut it off.

Take the cells out and let them rest for 30 minutes, then test them again with the ZTS tester.

If the value from the ZTS increases, there is a good chance the cells have developed a pacification layer inside. Once you burn this layer off the cells may perform as normal, at least in the short term.

Tom

16. Re: Simple guide to using a DMM for measurements

Tom,
Thank you for the guidance! I have plenty of one cell lights, I will get testing asap. What causes a pacification layer, and is there a cause that is avoidable? Thanks again, I really appreciate it!

17. Re: Simple guide to using a DMM for measurements

There is some pretty good reading material (as well as calculators) on Passivation and Depassivation on the Spectrum Batteries web site. Well worth a stroll down information lane.

18. Re: Simple guide to using a DMM for measurements

Hello Crazyeddiethefirst,

I guess I should learn how to spell...

The information provided by M4a1usr seems to explain what is going on.

The topic of passivation came up a few years back when BatteryStation was having some issues with their CR123 cells. They were manufactured in China and while they performed well they did not store well. This prompted Kevin to change manufacturers to Panasonic and the issue went away, for the most part.

At that time I ran across a white paper by Energizer stating about the same thing as is listed in the Electrochem article. In part that was that applying a load to the cell can burn off the passivation layer and restore the cell to like new condition, minus a small amount of capacity.

Digging deeper it seems that additives can be added to the electrolyte to retard this layer from forming and cheaper manufacturing processes may reduce costs by eliminating those additives. Also, impurities in the electrolyte chemicals can contribute to this problem.

The ZTS tester applies a load to the cell. Sometimes all it takes is 5 - 8 repeats of the test to burn off the passivation. Other times it takes a decent load. And still other times nothing helps. I just checked some BatteryStation mismatched cells from 2006. The started out at 80% on the ZTS in 2006 and I have been storing them to see what happens. When I tested I got 0% from these cells. After running them in a single cell incandescent light for a short time, they rebounded to 10%. There are a lot of variables involved and that makes it difficult to come up with a set way to try to recover the cells. I just end up using them in single cell lights.

After a number of tests and extensive evaluation I have decided that the ZTS gives me a heads up that something is going on. From there I usually subject those cells to a brief load and then rotate them to be used immediately. There are far fewer problems with quality cells, but sometimes they crop up.

Tom

19. Re: Simple guide to using a DMM for measurements

Wow, I only just discovered this thread because some kind soul resurrected it from obscurity in the past by necro posting to it. Like others, I add my thanks to HKJ and nominate it for a sticky.

Ed

20. Re: Simple guide to using a DMM for measurements

It's now a sticky.

Bill

21. Re: Simple guide to using a DMM for measurements

Originally Posted by Bullzeyebill
It's now a sticky.

Bill
Thank you, sir.

It will be much easier to find now when I'm trying to remember one of those more complex (to my mind anyway) techniques.

Ed

22. Re: Simple guide to using a DMM for measurements

Originally Posted by SilverFox
Hello Crazyeddiethefirst,

If you are up for an experiment...

Test your low cells and note the ZTS value associated with each cell that is in question.

Take a cell that showed low capacity on the ZTS and put it into a single cell light that draws reasonable current. If you don't have any, pick two of the cells that showed low capacity and put them into a multi cell light.

Next turn the light on for 15 - 30 seconds, then shut it off.

Take the cells out and let them rest for 30 minutes, then test them again with the ZTS tester.

If the value from the ZTS increases, there is a good chance the cells have developed a pacification layer inside. Once you burn this layer off the cells may perform as normal, at least in the short term.

Tom
Sorry for the delay, a few medical issues have kept me tied up. Well, I tried the testing as suggested, but no change if indeed it was caused by passivation. I tried using both LED & incandescent, in case the load was of consequence-no change.(there was no increase or decrease after application of load and recovery period). Any other ideas? Thanks!

23. Re: Simple guide to using a DMM for measurements

Hello Crazyeddiethefirst,

Well...

Perhaps it is time to just move on.

Tom

24. Re: Simple guide to using a DMM for measurements

I came to the same conclusion with one caveat-I am going to give Surefire a call and have a chat with them....thanks for your input!

25. Re: Simple guide to using a DMM for measurements

Very good guide! Could you someone explain how to measure the charging rate from a charger with the DMM ? It will be very helpful. Thanks

26. Re: Simple guide to using a DMM for measurements

Wow great guide! Thanks for sharing!

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