# Multimeter!



## foxtrot29 (Mar 14, 2009)

Not being an electronics guru whatsoever, I have a rather ridiculous question...

For testing LIon voltage, does the multimeter I purchase have to have any particular setting or range?

I was thinking of hopping down to my local crappy tire and buying this one (looks a little more robust than DX's testers):

http://www.canadiantire.ca/browse/product_detail.jsp?FOLDER%3C%3Efolder_id=1408474396672448&bmUID=1237051001437&PRODUCT%3C%3Eprd_id=845524442132041&assortment=primary&fromSearch=true

(use postal code N1R8C4)

And for pulse load testing, I already have a ZTS tester on the way....


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## coppertrail (Mar 14, 2009)

I've accumulated about 5 Multimeters over the years, and this is my primary DMM. Granted, I don't do much more than test batteries. As long as it tests DC voltage in the range of your batteries, it will work fine.


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## foxtrot29 (Mar 14, 2009)

coppertrail said:


> I've accumulated about 5 Multimeters over the years, and this is my primary DMM. Granted, I don't do much more than test batteries. As long as it tests DC current in the range of your batteries, it will work fine.



For $14, can't go wrong.

Purchased.

Mod's, please close! Unless anyone wants to discuss multimeters! I do I do! lol


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## Mr Happy (Mar 14, 2009)

coppertrail said:


> As long as it tests DC current in the range of your batteries, it will work fine.


Don't you mean DC _voltage_? Granted DC current has its uses, but voltage is the main test applied to batteries.


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## Mr Happy (Mar 14, 2009)

foxtrot29 said:


> For $14, can't go wrong.
> 
> Purchased.
> 
> Mod's, please close! Unless anyone wants to discuss multimeters! I do I do! lol


Actually, I would have purchased the Innova meter from Canadian Tire. The general quality of construction is better on the Innova/Equus meters, meaning they will probably be more reliable overall.


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## TakeTheActive (Mar 14, 2009)

foxtrot29 said:


> ...*For testing LIon voltage, does the multimeter I purchase have to have any particular setting or range?*


From my Sig Line LINKs:

*Interpreting DMM Specifications - A Detailed Example* - *Justin Case*​


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## oregon (Mar 14, 2009)

RadioShack 22-802 DMM: pocket-sized, easy to keep clean and safe by simply closing the lid, has held up for years of use and goes about anywhere in a tool box, glove box or pocket. Got a couple of them on sale years ago and haven't used my expensive fragile analog since.












Link to product manual pdf: http://www.radioshack.com/graphics/uc/rsk/Support/ProductManuals/2200802_PM_EN.pdf

oregon


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## foxtrot29 (Mar 14, 2009)

Mr Happy said:


> Actually, I would have purchased the Innova meter from Canadian Tire. The general quality of construction is better on the Innova/Equus meters, meaning they will probably be more reliable overall.



Yeah, and it seems to only be 3 1/2 digit, so I cancelled the order.

I'm on the fence here, don't know what to buy....


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## StarHalo (Mar 14, 2009)

You can do load testing using a digital multimeter and some Radio Shack scraps: 






You just have to create a circuit that puts a load on the battery, which is what resistors do. Above, I've put two 1 Ohm/10 Watt resistors in series for a total of 3.0 Ohms tested/displayed.

This circuit tests freshly charged Li-Ion cells at 1.38 amps, and NiMHs at .45 amps (or .91 amps if using only one resistor). It can also test 123 cells at exactly 1 amp draw.

Parts cost:

- Multimeter $3
- Resistor 2-pack $2
- Alligator clips $.60

Total cost: $5.60

 Please note that the multimeter in the photo is set to display the resistance of the circuit - never use this setting for battery testing! Always set your meter to DC Volts when testing batteries


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## foxtrot29 (Mar 14, 2009)

Ok, found one on ebay that is 3 1/2 digit, and for DC this is the accuracy listed:

* DC. Voltage* 200mV / 2V/ 20V / 200V / 1000V  ±1%,  ±2digits
+- 2 digits? Is this a bad thing?


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## Mr Happy (Mar 14, 2009)

StarHalo said:


> You can do load testing using a digital multimeter and some Radio Shack scraps:


For those less familiar with circuits, it may be worth pointing out that that picture is really dangerous. The meter is on a resistance range with the meter probes right next to a battery. It is just inviting someone to set it up like that and then put the probes on the battery.

For this test the meter needs to be on the DC volts range. If the probes are touched to a battery with the meter on a resistance range it could damage the meter.


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## Mr Happy (Mar 14, 2009)

foxtrot29 said:


> Ok, found one on ebay that is 3 1/2 digit, and for DC this is the accuracy listed:
> 
> * DC. Voltage* 200mV / 2V/ 20V / 200V / 1000V  ±1%,  ±2digits
> +- 2 digits? Is this a bad thing?


Well unfortunately for really reliable measurement of lithium ion voltages you need a meter that is 4 1/2 digits with a basic DC accuracy of about 0.1%.

To see why, suppose the battery has a true 4.20 V measurement. On the meter you have to use the 20 V range, which means you have readings up to 19.99 V. The uncertainty in the meter reading will therefore be 1% of 4.20 V (0.04 V) + 2 digits (0.02 V) giving 0.06 V total.

In the worst case the meter could therefore read anywhere between 4.14 V to 4.26 V. In reality most meters will not be right at the edge like that, but a good rule of thumb is never to trust the last digit.

I said unfortunately at the beginning because a 4 1/2 digit 0.1% meter will cost a lot more than a 3 1/2 digit 1% meter. However, you might like to buy a low cost but reasonable quality meter to get familiar with using it, and then decide later on if you want to spend a lot more on a more accurate one.


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## StarHalo (Mar 14, 2009)

Mr Happy said:


> The meter is on a resistance range with the meter probes right next to a battery. It is just inviting someone to set it up like that and then put the probes on the battery.



Very true, I've edited the post, ty for pointing that out.


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## foxtrot29 (Mar 14, 2009)

Mr Happy said:


> Well unfortunately for really reliable measurement of lithium ion voltages you need a meter that is 4 1/2 digits with a basic DC accuracy of about 0.1%.
> 
> To see why, suppose the battery has a true 4.20 V measurement. On the meter you have to use the 20 V range, which means you have readings up to 19.99 V. The uncertainty in the meter reading will therefore be 1% of 4.20 V (0.04 V) + 2 digits (0.02 V) giving 0.06 V total.
> 
> ...




Understood. I went with the canadiantire version, and it is 3 1/2 digit, *0.5%*. Seems like a solid quality meter (linked in one of my first posts above...)


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## BoarHunter (Mar 15, 2009)

This setup will give you wrong results as you measure the voltage drop of the contact points to the battery.
Do a search for Kelvin, 4 wire measurement method.


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## coppertrail (Mar 15, 2009)

Mr Happy said:


> Don't you mean DC _voltage_? Granted DC current has its uses, but voltage is the main test applied to batteries.


I did mean voltage :-S . Post edited.


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## TranceAddict (Mar 15, 2009)

get yourself a fluke DMM, cheap DMM is unreliable, do notice cheap one will read incorrectly when the battery level is low.


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## Justin Case (Mar 15, 2009)

One could get a calibrated voltage reference and probably use that in combination with an inexpensive meter.

ebay often has ones for auction from a seller named zildjianboy7. He also sells them direct from his web site at voltagestandard.com. He sells a trimmable version and a less-expensive, non-trimmable one (or he used to).

Most likely such a 5V reference will give you a good idea of your measurement error at 4.20V. If you are really lucky and your 3 1/2 digit meter specs out a little better than advertised, you might be able to use your meter's "relative" function to get 3 decimal places, even if your meter's voltage ranges jump from 4V to 40V. For this hypothetical example, take a 3V Li primary and measure its resting voltage. Your meter hopefully can read that voltage out to 3 decimal places. Press the Relative button to zero the meter relative to the voltage of the Li primary cell. Then measure the voltage of your Li-ion. Add that relative value to the voltage measured for the Li primary to get the absolute voltage of the Li-ion.

Normally, if your meter range goes from 4V to 40V (for example), the Li-ion voltage measurement will be at 2 decimal places. But by using the relative feature, you might fool the meter and obtain 3 decimal places since the nominal 3V measurement of the Li primary should be at 3 decimal places.

Another approach could be to compare your meter to the measurements from a known-accurate meter like a Fluke 87 V.


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## Black Rose (Mar 15, 2009)

foxtrot29 said:


> I was thinking of hopping down to my local crappy tire and buying this one (looks a little more robust than DX's testers):
> 
> http://www.canadiantire.ca/browse/p...4442132041&assortment=primary&fromSearch=true


That one goes on sale quite regularly for under $10. Next sale should be coming along in a few weeks.

I have 2 of them.


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## foxtrot29 (Mar 16, 2009)

Black Rose said:


> That one goes on sale quite regularly for under $10. Next sale should be coming along in a few weeks.
> 
> I have 2 of them.



Canadian tire was having a huge sale while I was there.... Clearance, 40-75% off! But alas, that item was not on sale.

I'll stick with this one for a while, my next one will probably be a fluke! lol

I have a ZTS tester enroute anyway...


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## Black Rose (Mar 16, 2009)

Where did you get your ZTS from?


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## Justin Case (Mar 16, 2009)

Many sources on the Internet -- Lighthound, Battery Junction, Thomas Distributing, amazon, B&H Photo, ....

Not sure, however, how a ZTS substitutes for an accurate DMM when it comes to Li-ions. If the Li-ion measures 4.25V on a Fluke DMM, what will the ZTS tell you? 100% capacity remaining? A CBA II looks like a better product for battery testing, though more expensive and complicated, and perhaps also overkill.


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## Black Rose (Mar 16, 2009)

Justin Case said:


> Many sources on the Internet -- Lighthound, Battery Junction, Thomas Distributing, amazon, B&H Photo, ....


I am looking for a Canadian supplier so that I don't have to add 30% on top to deal with the US-CDN exchange rate.


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## foxtrot29 (Mar 16, 2009)

Black Rose said:


> Where did you get your ZTS from?




Got it from lighthound for $28.xx... Of course, +12.95 shipping.

So to make it worth it, I threw on about 10 CR123's and a battery holder.


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## Justin Case (Mar 16, 2009)

foxtrot29 said:


> Understood. I went with the canadiantire version, and it is 3 1/2 digit, *0.5%*. Seems like a solid quality meter (linked in one of my first posts above...)



Are you sure that the voltage accuracy spec is 0.5% with zero offset error?

I can't find the 4320 on the Equus web site. They have a 3310, 3320, and 3340 DMM. The 4320 looks closest to the 3310 cosmetically.

The 3310, 3320, and 3340 all have a voltage accuracy spec of +/-(0.8% + 5 digits). IMO, that's bad. The 5 digits of offset error is a lot for a 3 1/2 or 3 3/4 digit DMM.

If the 4320 has 5 digits of offset, IMO you would do better to get another DMM.


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## foxtrot29 (Mar 18, 2009)

Justin Case said:


> Are you sure that the voltage accuracy spec is 0.5% with zero offset error?
> 
> I can't find the 4320 on the Equus web site. They have a 3310, 3320, and 3340 DMM. The 4320 looks closest to the 3310 cosmetically.
> 
> ...



It's 0.5% + 2 digits I think.


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## Black Rose (Mar 18, 2009)

foxtrot29 said:


> It's 0.5% + 2 digits I think.


Nope.

I just grabbed the manual for the 4320a and it is +- (0.8% + 5 digits) for DCV.


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## foxtrot29 (Mar 18, 2009)

Black Rose said:


> Nope.
> 
> I just grabbed the manual for the 4320a and it is +- (0.8% + 5 digits) for DCV.



I'm looking right at it now, and it has different accuracy depending on the setting. The setting for 20v shows as 0.5% + 2 digits. Several of the other settings have either 0.8% or even 1.0%. But not the setting I'm using it for.


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## Black Rose (Mar 19, 2009)

Do you have a 4320 or a 4320a?

The docs for mine show +- (0.8% + 5 digits) for 20V


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## foxtrot29 (Mar 19, 2009)

Black Rose said:


> Do you have a 4320 or a 4320a?
> 
> The docs for mine show +- (0.8% + 5 digits) for 20V



It is a #4320.

That's what it says on it's face and on the manual!  Unless there is some kind of misprint. I had to look at it twice when I read your post!

[EDIT]

I wasn't aware there was a 4320a... I wonder what the differences are -- other than accuracy, obviously. the "a" one would think would denote that it came AFTER the 4320 -- and thus should be better? lol who knows.


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## Black Rose (Mar 21, 2009)

foxtrot29 said:


> I wasn't aware there was a 4320a... I wonder what the differences are -- other than accuracy, obviously. the "a" one would think would denote that it came AFTER the 4320 -- and thus should be better? lol who knows.


When I bought mine, they had the 4320 and the 4320a, so I bought the "a" version thinking it had some improvements. Maybe not:thinking:

The 4320a has ©IEC 2006 on the front. I think the regular 4320 has 2004 on it.


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## Black Rose (Apr 25, 2009)

foxtrot29 said:


> I wasn't aware there was a 4320a... I wonder what the differences are -- other than accuracy, obviously. the "a" one would think would denote that it came AFTER the 4320 -- and thus should be better? lol who knows.


I picked up a 4320 yesterday at Partsource for $7.99. I couldn't resist at that price 

In comparing them, as we already determined, the 4320 has better accuracy levels than the 4320a.

The 4320 has 4 battery load test modes (1.5v, 6v 9v, 12v), whereas the 4320a only has 2 (1.5v & 9v).

The 4320a has one additional DCV and OHM setting.


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## timelake (Sep 9, 2009)

oregon said:


> RadioShack 22-802 DMM: pocket-sized, easy to keep clean and safe by simply closing the lid, has held up for years of use and goes about anywhere in a tool box, glove box or pocket. Got a couple of them on sale years ago and haven't used my expensive fragile analog since.
> 
> 
> 
> ...




To Oregon: Hi. I was searching the internet to find this meter for sale anywhere, by anyone, and I came across your entry in this forum - great photos by the way! I hope you don't mind my asking,... if yours becomes available, please let me know as I will purchase from you. In any case, I'll appreciate your reply via email: "timelake 'at' mfire.com" thanks TimeLake


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## elwood (Sep 10, 2009)

I have the Equus 3320 and it seems to work fine for me.

One huge thing i hate about it is the contrast! It's a really good thing they have a little kickstand built into it on the back because you definitely need it to read the numbers!

Other than that i think it was a decent purchase for $18 overnighted from amazon.


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## oregon (Sep 10, 2009)

timelake said:


> To Oregon: Hi. I was searching the internet to find this meter for sale anywhere, by anyone, and I came across your entry in this forum - great photos by the way! I hope you don't mind my asking,... if yours becomes available, please let me know as I will purchase from you. In any case, I'll appreciate your reply via email: "timelake 'at' mfire.com" thanks TimeLake


 
Emailed reply this AM.

oregon


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