How To Test Standard AA, AAA, D, C, and 9V Batteries with a Multimeter

[@TangodownNZ]

All the other videos just check the voltage and say that’s how you test them. You are showing us the correct way. 🙏

[@george5120]

Thanks for not playing music and thereby trying to fancy yourself as an actor in a Hollywood movie, like in so many other KZbin tutorials. Just straightforward discussion about battery testing, which is all that we needed.

[@GerardPinzone]

Video starts at 3:30

[@EggheadJr1]

thank you so much!

[@niamhwhite6621]

it matters

[@niamhwhite6621]

gerard pinzone - wish i had seen your comment!!

[@satan4635]

This comment was more helpful than the video.

[@jizelcastinon5022]

Gerard Pinzone boi

[@harryshector]

A nominal 100 ohm load will draw 90 mA from a nominal 9 volt battery. 90 mA is a considerable load for a ‘transistor radio battery.’ They are normally used in significantly lower current applications. I would say 10 to 20 mA is a reasonable load. So, a 450 ohm resistor would approximate that kind of load. Drawing 90 mA might lead someone to discard a battery of this type prematurely. A “D” cell is intended for much heavier loads than the approximately 16 mA that the 100 ohm load would draw from it. Such batteries are intended for loads of 200 to 500 mA. A three ohm load will draw 500 mA from a 1.5 volt battery. This would be a much more useful measure of a D cell’s performance, because the 100 ohm load would seem to the D cell to be nearly an open circuit. So, I think the idea behind your tutorial was correct, but I think that the information given could be, depending upon the circumstance, misleading. The Radio Shack Battery tester that I have tests D cells at 150 mA. I don’t think that’s a reliable measure of performance for D cell batteries. It would be reasonable for AA cells, I think. There are also valid questions of what the cutoff voltage should be for the cells tested. Battery literature will give suggested levels, and may vary considerably from manufacturer to manufacturer. At the end of the day, most devices require high enough voltage on the cells used that most of the capacity of the battery is wasted anyway.

[@carlosmanuelgonzalez310]

Thanks 👍

[@G56AG]

I have a 9 volt battery sitting on my desk, using just a multimeter it tests 8.94 volts, there appears to be lots of life left in that battery! Now we test it the way you should, under a load, now it tests 2.83 volts, all its really good for is the recycling bin. Thank you for posting a proper method to test a battery, under load.

[@Peppermint1]

People, not every video is perfectly done, at least he gets to the point (at 3:30) and tells us the correct way to test these batteries, which I guess most of us were not aware of. Only thing I would improve, is to add in the title "and with an 100ohm resistor"

[@PetsoKamagaya]

Awesome, just found this video from 2013 and is very useful even in 2022!!! Thank you.

[@johnmitchelljr]

I love it when I find I've been doing things wrong. Now a trip to the resisters "r" us store. Thank you.

[@jeffreydeutsch7336]

While the author clearly understands what is going on with internal resistance, he fails to address what is a reasonable test load. His hundred ohm resistor will only draw 15 ma from a 1.5 volt battery. For a D cell that is an improbably small load. The shortcoming of any load tester is that the manufacturer has to guesstimate a load for any battery it tests, not knowing what load the battery is being asked to drive. The better cheap load testers have different loads for AA, C,D, 9V, etc. In fact, a 9v battery is made up of 1.5 volt cells that are way smaller than a AAA. In normal operation, they probably don't have to supply that much current. A smoke alarm might be an exception, I never checked. The point is, no one value resistor is going to simulate a reasonable load for a whole range of batteries. I remember seeing the schematic for a Radio shack load tester and was thinking of making a little test box using the values they used for different sizes of batteries, with my multimeter. I have seen them at Home Depot ,too. For around 10 or 15 bucks it is probably easier to buy one. Another problrm with s multimeter is the awkwardness of two probes. Most of the testers have a sliding battery holder or a contact on the face and only one probe. I you test more than very rarely, two probes with a resistor clipped across them is pretty clumsy to use.

[@JamieClark]

If people knew this, I think a lot more of those radio-shack style testers would have been sold... too bad they don't exist anymore!

[@toddy2519]

The load testers or RS doesn't exist? I ask because there is a RS here in my town.

[@Milesco]

@Anonymous : Search for "battery testers". They're supposed to have a load built in, but in my experience, it's nowhere near a heavy enough of a load to really test the battery with any real accuracy. That's why I prefer to either put a fairly heavy load (e.g., a 1-ohm resistor) in parallel with the battery tester (I happen to have one where it's easy to do that, but most of them aren't), or do the same thing with an actual multimeter, like the guy in this video did..

[@spacecon4982]

@@JamieClark Yes, Radio Shack used to sell a lot of unique things that you couldn't get anywhere else. Their big downfall was switching from and electronics store to a cell phone shop.

[@yuyiya]

@Jeffrey Deutsch : One well-informed comment, like yours makes reading them ALL worth the time :-)

[@MarcCastellsBallesta]

That's what I was missing! Testing the batteries against a resistor to see their voltage when plugged in a circuit. Thank you!

[@arthurserino2254]

I"m so fortunate to have a multimeter with this functionality built in for 1.5, 9, and 12v batteries! Cost me all of $11 on amazon!

[@star-lordlavaplanet]

Could you please post a link to your device thank you

[@arthurserino2254]

@@star-lordlavaplanet Actron auto-analyzer.

[@MrHolz1234]

@arthurserino2254 Do you know what the resistance load is for each of those? Does it vary with each setting, or is it just a single load? The Instruction manual for the Actron 6635 auto-analyser does not provide any ohm load information, just that it tests under an unspecified "load" for each battery setting. Thanks.

[@arthurserino2254]

@@MrHolz1234 I tested it once with another multimeter. I don't remember the values, but it varies.

[@MrHolz1234]

@@arthurserino2254 Thanks, it is useful to know that they do use different loads for each one.

[@AndrewTanielian]

The info on the resistors is great. Thank you for including that!

[@victoryfirst2878]

Thank you for reviving my memory on battery testing Sir.

[@dggd]

Well I'll be darn, I learned some valuable new information today. I appreciate this very much. Thank you.

[@kitsurubami]

1) need multimeter, ~100 (known) ohm resistor, alligator clips 2) check the batteries while under load (passing through the resistor) This is more telling because besides the battery having enough voltage, it also needs to have a low enough internal resistance (able to put out enough voltage while under load). I don't know anything about electricity, I'm just taking notes, correct me if i'm wrong.

[@Milesco]

Yep, that's correct. Although I would suggest a much lower resistance (higher load). 100 ohms isn't going to put much of a load on a battery, so it won't really put the battery to the test and show you "what it's made of", so to speak. You need to draw a fair amount of current out of a battery in order to see what its internal resistance is doing. I would suggest a 1-ohm resistor for a AA battery. That may sound like a heavy load to some people, but it's only for a few seconds, and it's what you need in order to really see what's going on inside the cell. A good battery will be able to tolerate that without a problem and without a large voltage drop. If, under that kind of load, it still gives you a volt or more, you're good to go. Between, say, 8/10ths of a volt and 1.0 volts, you're still okay, but it's weak. Below around 0.8 volts, you should consider tossing the battery (or recharging it if it's a rechargeable).

[@mick1turner]

@@Milesco Hi Captain. I may not be that smart but are you saying 1 ohm has more resistance than 100 ohm, or is it because the resistor is in parallel ?Sorry just trying to get my head around all this

[@Milesco]

@@mick1turner No, 1 ohm is of course much less resistance than 100 ohms - but that means it draws much more current. It puts a heavier load on the battery. A resistor resists the flow of current, so more resistance = less current, and less resistance = more current. So a low resistance is a heavy load, and a high resistance is a light load. When you’re testing a battery, you want to put a heavy load on it (high current), so you want to use a low resistance. Any battery will look good if you just put a tiny little load on it. You want to push it hard to see if it can “deliver the goods”. I guess maybe you're thinking that a low resistance makes it “easy” for the battery. Like if you're pushing a cart with low-friction wheel bearings, it’s easy to push. But that’s not the right way to think about it. Having a low resistance makes it easy for the _current to flow._ But it’s a heavy workout for the battery. It’s like opening up the throttle on an engine. The throttle resists the flow of fuel and air into the the engine. Open up the throttle (reduce its resistance), and it’s easy for lots of fuel and air to get into the engine, and the engine will deliver lots of torque. But it’s a heavy workout for the engine. Every battery has an internal resistance, and a good battery can deliver a high current flow because it has a low internal resistance. Conversely, a bad battery has a high internal resistance and therefore can’t deliver a high current, even if you put heavy load (that is, a low external resistance) on it. That’s because the battery’s high internal resistance becomes the limiting factor. You’ll see a large voltage drop when you try to put a heavy load on it. Like water flowing through a pipe - if you put a restriction in the pipe, the water pressure will be high on the front side of the restrictor, but will be low on the back side. In an electrical circuit, voltage is the “pressure” that forces electrons through the circuit. Hope that helps!

[@nittijain]

@@Milesco awesome teacher u can be😘

[@Milesco]

@@nittijain : Thanks, Nitti! 😊

[@matthewralph5068]

Thank you .. now i know that to truly test a battery, i need to test it under load. i've learned someting new watching your video.

[@nonshatter7]

Good video, I learned something new here. The intro was also useful to understand the reasons for a poor battery. I’m looking for a high quality battery charger and this video covers some of my ancillary research on the topic.

[@mikelitteral2366]

This guy should be a hand model. Great job

[@mamikim7812]

thank you for your clear explanation, we need a load to test. Blessing from Hong Kong.

[@frugalprepper]

I use the 9V battery tester that God gave me. I just put the terminals on my tongue and if it hurts bad, it is good, and If it only hurts a little chuck it.

[@knurlgnar24]

The tongue method does work but only puts a few milliamps of load on the battery so it may still pass bad batteries. However it is a fairly reliable quick check!

[@Shroomflies]

Popeye I believe I speak for all when I request video evidence of said test!

[@radellaf]

100 Ohms is a very light (10-15mA) load for AAA - D cells. I used to wedge the leads of a 1/2W carbon 10 Ohm resistor into the banana plugs at the meter terminals to get a less optimistic reading at 100-150mA load for AA cells. That's a bit light for a D alkaline but more realistic I think. 100mA is a runtime of about 1 day for an alkaline AA, so at least the right order of magnitude for most devices (3-30 hour runtime). Zetec makes a fancy pulse load meter that isn't so cheap. It is popular but compared to this, I don't think worth it.

[@awizardalso]

Thanks for the load resistor value. I want to build a battery tester and wasn't sure of what to use for a load for reliable testing. I would think you should test for a little longer to see if the voltage starts to drop. I think if it drops at a slow rate it's still good, and at a faster rate maybe not so good.

[@belowmars]

Do we test NIMH, lithium ion and zinc chloride batteries the same way? Does the resistor have to be 120 ohms or is there a range I can choose from? I thought for the AA and AAA batteries a 10-20 ohms resistor is more than enough? Since they only output over 1 volt.

[@NiHaoMike64]

Some fancy multimeters have a low impedance mode that can be used for this.

[@TONYMLT]

Good review. Very good intro explanation of the initial comments on what you can and not do when testing the batteries. Well done mate.

[@joegoodman9232]

Thanks for the education. On my craftsman MM you wonder why they put 1.5 and 9v settings position on the dial ? It just doesn't work!! Thanks

[@vibhupande]

the most useful video on testing batteries, that i've found this far, mainly coz of the comments.. thanks everyone!

[@SuperRugby11]

Thank you very much for this great information. I am not an electronics person, so this is invaluable

[@joeProcess]

learned more from reading the comments than watching the video, most importantly, video starts at 3:30, measure voltage with a known load.

[@richardward7525]

Absolutely terrific, high value post!!!

[@huttarl]

Why 100 ohm? Will 1 ohm or 1000 ohm work? It sounded like you said those resistors in the package were 1/4 ohm... will that work?

[@knurlgnar24]

You just want enough current to stress the battery enough to know it will work in real-life applications. The exact resistance isn't terribly important unless you want to be scientific about it. That said 1000 ohms is definitely too high, and 1 ohm is lower than the internal resistance of the battery and will always yield a 'fail' result. For a AA to D cell 500mA is about as high as you'd want to go (flashlights are in this range).

[@bitTorrenter]

@@knurlgnar24 So, you're talking about the 9V battery then. The impedance on the AA,AAA, B,C & D batteries I understand to be much lower.

[@slamdunktiger]

Thank you very much for this awesome video, really helpful. I DJ weddings and use half a dozen batteries per gig for wireless microphones and wanted to be able to check them.

[@ScepticLlama]

ok, just for clarification here. When you say "this battery is bad", do you mean the battery is drained of its power, or that the battery in general is bad and would drain quickly/not provide the required power?

[@2k3r11s]

That was an 9V alkaline battery (not rechargeable), so the answer is "both".

[@robertjusic9097]

It just means that the battery is unable to give the required electricity to the device it would be charging

[@TennesseeSniper]

Great video , I just ordered some clips for the resisters I have to help test. 👍 , 1 quick question: so if I don’t use the resister and the battery reads at 1.1v~1.2v it could still be good ?

[@goodun6081]

No, if a 1.5 battery is reading 1.1 or 1.2 volts on a digital voltmeter, without any kind of load on it, it's garbage, it's dead, throw it out. If that battery was brand new it should be reading about 1.6 or almost 1.7 volts on a digital meter, without any other load. A used battery that measures 1.5 volts might seem to be okay, except that when you put a load on it it might deliver only about 1.3 volts or so, and obviously that isn't very good in many devices. As a quick and dirty battery tester, check the batteries with an analog ohmmeter, that will have a lower resistance than a digital meter and would load down the batteries a bit more. If a battery reads 1.5 volts or a little higher on an analog meter, it's likely to have some life left in it.

[@mikewellwood1412]

If these are alkali batteries, you _might_ want to consider recharging them. Although alkali batteries are not supposed to be rechargeable, a lot of people do. (See many other videos on YT for ways of going about this, but the main thing is to do it in such a way that it does not overheat). If you can get it back up to about 1.5V or more, then it might be ok. But importantly, you will want to test the internal resistance (i.e. by using the procedure shown in *this* video ), before you think of attempting to recharge it. If the IR is too high (i.e. the voltage measured under load is much below 1.0 V, then it's probably not worth attempting to recharge. The biggest risk with recharging alkalies is possible leakage, so not worth risking in expensive equipment where leakage could be a disaster. Some people have reported batteries exploding while being charged, although I believe that is a lesser risk unless one is very careless (leaving it too long, unattended, or at too high recharge current. There are specialised rechargers around for "non-rechargeable" batteries, that use small amounts of pulsed current. Sorry if this is of no interest to you, but it might be of interest to someone.

[@Minimalist_Wonderer]

can we test AA & AAA rechargeable batteries with the 10W 150 ohm aluminum resistor?

[@ItsVideos]

4:10 - So, to use the 1/4 ohm resistors, you would connect 440 of them in series to get 110 ohms?

[@knurlgnar24]

Whoops! Quarter watt! lol

[@Bodhi1satva]

Will any 100 ohm resistor add enough load for all these regular use batteries? I started looking for a resistor and realized that there are other factors like some are 1/4 W, some ½ W. I think maybe theres some info missing here about the proper load to test each type of battery if I’m not mistaken. ie; what resistance would apply the appropriate load for double A or triple A batteries as opposed to 9 V or 12 V batteries?

[@george5120]

I cannot figure out how he connected the resistor because the video is cropped. And yet, that connection is the most important point of this video!

[@knurlgnar24]

I'm sorry for the poor video coverage of that connection. The resistor is in parallel with the battery simply to draw a load on it. This allows for doing internal resistance measurements without a special meter.

[@george5120]

@@knurlgnar24 I ended up buying this ZTS Inc. MBT-1 Multi-Battery Test because I learned that a resistor of different strength is needed to load-test different batteries with a multimeter; and I just don't feel like buying a bunch of resistors: www.amazon.com/gp/product/B000FQG1XE/

[@ravichandel8690]

i want to know what type of load is good for battery test and should it be applied in series or parallel to get load test in a battery. can i use salt water also to test battery load if possible

[@Christofftheman]

Thank you dude, I’m off to eBay to get myself a 100 Ohm resistor and 2 crocodile clips.

[@channelron3593]

Nice job, thanks for posting.

[@accidental_relevance]

So there are multimeters with a built in 100-ohm resistor ? Any recommendations on a brand ?

[@knurlgnar24]

Many multimeters have a 'low z' function to remove stray voltage from voltage measurements. It's not exactly the same but it's usually a few kilo-ohms and can be useful for coin cells and other low drain battery applications.

[@timhardman4764]

@@knurlgnar24 I have super cheap Harbor Freight multi meter. It has a function on the dial to test 9v and 1.5v batteries and it does the test adding 370mW of resistance and it measures the battery in mAmps instead of volts. For a 9v battery, it says normal amperage is 25 mA with the 370 mW of load in effect and for a 1.5v battery it says normal Amperage is 4 mA. I can still measure volts on the dial using the DCV 20 setting. In you opinion is the mA a good way to measure battery health and does anyone know the range in mA for a healthy battery in 9v and 1.5v batteries. Example: is a reading of 20 mA (80% of 25) mean I still have a strong battery? Is there a scale or chart somewhere that gives numbers for Excellent, Good, Fair and Poor regarding the mA measurement or the Voltage measurement with 110 ohms of resistance added?

[@wn_djogja]

My Sanwa SP-15D analog multimeter has a 'Battery' setting that 'Load' the battery with internal 10 Ohm resistor, this resistor value is written on the scale... I consider a battery bad when it read ±1V(@10Ω load)

[@americandowninbrazil]

Thanks for this video man! It is exactly what I was looking for!

[@LeonardoGarcia-bt9ci]

Hey been a while

[@RangerOfTheOrder]

Thank you for this. The beginning was a tad winded, but still provide some useful info. We used to have an analog MM with a battery test function. When that crapped out we picked up a DMM but couldn't find any that could test batteries.

[@lw216316]

radio shack had a resistor (2 pack) and test leads (3 pack)- about $8 bucks- I only needed one resistor but the 2 pack was so cheap it was okay. But the 3 pack test leads were about $8 and I hate paying for what I don't need.... so shopped and found a single pair of test leads at Walmart for $2 (made by 3M,,, 30inch) and returned the 3 pack to Radio Shack. Thanks for the video. I was finally able to go thru a drawer full of old batteries and get rid of bad ones.

[@jeffkrebs]

This was truly really interesting. I just bought Duracell procell because my bass guitar has active pickups. worst thing would be playing and battery suddenly dies because I tested without a load. Thanks - great well explained video

[@112aslann]

Can you test without load resister or something else that has 100 ohm? Like putting the battery inside of (for example tv remote) and then put the multimeter on both ends while its inside the remote?

[@knurlgnar24]

Yes, perfectly valid so long as the device you are testing it in is the device you intend to use it in. Sometimes a battery will work just fine at a low drain in powering something like a clock, but not work at all powering something like a flashlight. If it doesn't work in the high drain device it's still a 'bad' battery but that matters little if it works well in the application you are using it in.

[@112aslann]

@@knurlgnar24 Thanks for the quick answer :D

[@MarzNet256]

Very well explained. I'm gonna get some clips and a 100 Ohm R to go with my meter. I've got a boatload of batteries to test.

[@Milesco]

I would recommend using a much lower-value resistor. A 100-ohm resistor doesn't put enough of a load on a battery to really test it. You need to draw a fair amount of current out of a battery to see what kind of condition it's really in. I would recommend 1 ohm for 1.5-volt cells, and around 5 ohms for a 9-volt battery.

[@jpisty]

Ahhh ok this makes sense now. Just learned something new today. Thanks man

[@charlesdarwin6349]

Can I use this method to test 18650 battery? 100 ohm still sufficient?

[@chandrasekharraobonu2468]

5ohm is enough

[@philipmurray4065]

I tested this with 220 ohm resistor so my results will still be reliable? For example how many volts should I expect with 220 ohm resistor from 1.5v battery?

[@sfdurazo]

I have a 12v battery for a Power Wheel car and I have resistors like he showed in the plastic pack. Are those resistors enough to test the battery? Thank you in advance.

[@Flowing23]

excellent demo 👍👍

[@newmanhere4865]

Does the WATTAGE of the resistor we use matter when using this method of testing household batteries? And does the 100R seen as part of the specs for 100ohm resistors important? Would a 25W 100R 100ohm resistor work?

[@knurlgnar24]

Wattage doesn't matter much as long as you only test for a few seconds at a time. For most people buying a battery load tester off of Amazon is probably a more practical solution.

[@newmanhere4865]

@@knurlgnar24 Thanks alot for the quick reply.. I think I'm going to stick with the battery testing method you describe in your video.. seems like far too many Amazon load tester reviews describe VERY inaccurate test results as well as low quality hardware and/or product DOA in their comments! Would the 15 Amp rating of these aligator clip and wire set tend to scew the test results? : www.amazon.com/dp/B072C8G3XJ/?coliid=I19U49E5OARY17&colid=5T4XRIGDBIE&psc=1&ref_=lv_ov_lig_dp_it

[@tomatojuice12]

Thanks so much for this video. Can you explain why all those batteries should be 1.5 V? or near 1.5 V? (except the 9V)

[@yuyiya]

@tomatojuice - They're all _designed_ to deliver about 1.5 V. The 9 V battery consists of 6 smaller batteries ("cells"), each of 1.5 V, connected in series (positive to negative). This design value of 1.5 depends on the chemistry inside the battery, specifically, on the materials used in the two terminals and on the electrolyte (conductive paste or liquid) between them.

[@smudger304]

Is it possible to test the batteries whilst still in the item they are for? Put them under load and test which ones are faulty that way?

[@knurlgnar24]

Yes, that is a fully valid way to test them so long as the device you're testing them in has a fairly high current draw. A flashlight for example will work well as a battery tester. A remote control won't.

[@GrayMan619]

Great video, thank you for preparing such helpful content.If I were to apply what you have shown for ups batteries how would I go about estimating the right resistance for a 12v 7AH lead acid ups battery to replicate load in a UPS designed for 1500VA that takes two (2x) 12v 7AH batteries in series?

[@Milesco]

You mean two 12 v batteries in *parallel.*

[@wilsonlai4671]

thanks for this great video! does this process works on testing a 12V lead acid battery or do i have to increase the resistance instead before testing?

[@jusb1066]

lead acid car batterys are usually ok to check using just your meter, no resistance needed, if you get 12.4-12.7 , youre battery doesnt need charging

[@knurlgnar24]

A lead acid starting battery requires either an impedance test using a specialized tester, or a heavy load (>100A) applied for 10 or 15 seconds while measuring the voltage to determine if they are good. Professionals used to use expensive adjustable carbon pile load testers for this purpose but are increasingly using the digital impedance measuring type now. For most people it is most economical to just go to an auto parts store where they'll test it for free.

[@Odyss2023]

Use something like a 12v 60w light bulb as a load.

[@computerhome4309]

Thanks! How inaccurate would readings be using a 75 Ohm resistor (it's what I have on hand)? Also, I have situations where I temporarily use four AA batteries in a garden hose timer. Between uses I remove the batteries and label them for use in the same device in the future. This test will help me understand how depleted they are each time I use them, or whether one gets depleted faster than the others. It has been my understanding that if using multiple batteries in a device they should be of equal power.

[@asinegaasinega]

hope you realized that it's ok to use that for a garden hose

[@spotlight761]

Why do you use the load and how it affects the voltage shown in the powercell battery?

[@knurlgnar24]

The load allows us to measure the battery's internal resistance

[@mark2035]

Useful little video. Thanks.

[@johnriver8125]

Cool thanks. I have a bunch of 9's specifically so sounds like I should pick up the 10 watt then. It was only a few bucks so it will be worth it to use long term... Thanks for the feedback, haven't taken electronics since 9th grade This really helps ;)

[@knurlgnar24]

If you're like me you'll find multiple uses for that 10 watt resistor anyway. ;)

[@osscar29]

Great video mate, I've been totally confused by why my correct volt batteries wasn't working in the kids toys. Especially found the first half of the video enjoyable and informative. I think the number of people moaning about not getting to the point are a bunch of disinterested wankers and I would ignore them.

[@a11Oop968]

Same for me! I liked the preamble - it was educational. If I have 6 used batteries in a bag and I know someone threw one new one in there and I have no idea which it is, using a flashlight (good example) is not the ideal way to find the good battery. I, too, could not understand why my rechargeable batteries showed good on the multimeter after charging them, but hardly lasted at all in a motion ceiling light.

[@TheTomar33]

I saw another video "ChrisFix" use a Multimeter to check his car battery, does that hold true for car batteries too?

[@docferringer]

If it is a "maintenance free" battery you can test it with a multimeter. BUT if the battery has those removable plastic covers that let you add water to the individual cells of the battery then you need to use a hydrometer instead.

[@rpbajb]

Is it dangerous to test an 18650 Li-ion cell using a low resistance load, say 1 or 2 ohm? At what point does a low resistance become a short circuit?

[@knurlgnar24]

A cell at 3 or 4 volts can be tested with under 1 ohm without issue. 'Short circuit' is a term that depends on context. A 10,000A current in a powerplant may be considered a small load. A 1A current in a watch battery would be considered short circuit. Currents need to stay within the bounds that the components are built to handle, so without more information it's difficult to answer the question.

[@rpbajb]

@@knurlgnar24 Thanks. I want to test the internal resistance of some older flashlight cells, but I don't need any explosive excitement.

[@mickaels-g1479]

I see we have a lot of combinations to choose, however, I cannot find either 100 or 110 ohm. Which one would you recommend amongst the following please? 1- 10W at 150 ohm 2- 10W at 10 ohm 3- 50W at 8 ohm 4- 25W at 15 ohm 5- 10W at 390 ohm 6- 25W at 180 ohm 7- 100W at 1 ohm Many thanks...

[@nickguy6820]

Mickael S The idea here is to put "some" load on your battery. "Some" is highly subjective, and might be tweaked depending on what you want to do with the battery. If you know it will go in a particularly high-current device, you might choose a much lower resistance for your test. (5-20R, maybe.) If you just want to sort out good batteries from clearly bad ones, anything from 50-200R is fine. For most uses, 1-10R resistors are a little on the heavy side unless you're interested in stress-testing batteries. It's not really a fair comparison to most real-world loads, and just drains the battery unnecessarily. OTOH, 390R isn't enough load to prove much. It's about the same as a single indicator LED (~4mA). Regardless, you don't need 10 to 100W ratings.. that's gross overkill. You're never going to pull 10W from a AA battery, much less 100W. (Even at 1R, that's still only like 2W.) But if you already have it, or might use it elsewhere, that's fine.

[@giancarlo426]

How did you determine to set the resistance equal to 100 ohms? Would this be a reasonable resistance to test a 12 V car battery with? Thanks.

[@knurlgnar24]

A 12V car battery would require a far lower resistance - low enough to draw a couple hundred amps! The optimal resistance depends on the battery type and the application and I showed 100ohms here only because it is safe to use on all alkaline batteries.

[@sdillon4605]

what if my multi meter has a battery symbol with 9V and a battery symbol with 1.5V ,are those putting a load on to test?

[@knurlgnar24]

Yes, if your meter has a battery setting it already puts a load on the battery and all you need to do is read the voltage. The actual load varies substantially from meter to meter but for most purposes it's good enough.

[@bryanshoemaker6120]

100 ohms for basic batterys 1.5v, how about 7.4V 2200mah (16.28WH)? will 100ohms still be enough?

[@tertia0011]

For 9V battery use the tongue test - put battery terminals against tongue - if you feel a strong tingle battery is good. Takes 10s & no multimeter or load resister required. You will get a buzz.

[@rajeshchhabra326]

What is the name of that device which you attached with the multimeter

[@fredcdobbs823]

What do you think of the Harbor Freight free-with coupon Cen-Tech multimeter with the 1.5/9v battery test position, will that properly load a cell for an accurate test?

[@jeffreydeutsch7336]

Fred C Dobbs That is just what it does. there is an internal resistor but it is in series with a milliameter rather than in parallel with a voltmeter. the milliameter is very low resistance so the resistor is most of the load. Using ohms law, the resistor is 375 ohms. The meter says the battery should produce 4ma with that load.If it shows less it means the voltage is down. For a 9 volt battery you should see 25ma.This tester reads current, not voltage on the battery test function. To do it the other way, get some load resistors and use the voltage range.

[@waltright648]

So the resistor is connected in parallel rather than in series with the battery?

[@Teukku]

Hi, I have a bunch of CR2032 3V batteries and I would have to know if any of those are dead. How should I test it? I only have multimeter currently.

[@happycat0411]

I have a 1.5 volt, 9 volt, and 12 volt battery setting on my multi-meter. Can I use the 12 volt setting to load test the car battery in my vehicle?

[@curiosity2314]

Liked that, question from the past... It has been said to keep these types of batteries cold or frozen to get greater life, any ideas on this?

[@knurlgnar24]

Standard Heavy Duty or Alkaline batteries will self-discharge slower when cold and will also corrode more slowly when cold. However temperature cycling does the opposite so if you put them in a refrigerator or freezer that self defrosts (gets warm/cold/warm etc) then I don't think it is doing much good. Alkaline batteries have a very long shelf life so for practical purposes I would recommend storing them in a cool dry place rather than a refrigerator. A manual defrosting chest freezer would work well though to maintain optimal battery freshness.

[@pianoman74]

Very good video!! Finally ending the myth of "just hold (+) and (-) to the batteries, and if the voltage looks good, your battery is OK". There's lots of remainder voltage in a battery when it has NOT been used for a long time, so that approach is fruitless.

[@andrewzhang]

Is it safe to say that while voltmeters can't definitively determine if a battery is good, it can definitely tell if a battery is bad if the measured voltage is below the rated voltage? Thanks.

[@waynegram8907]

Knulganar24, how do you test the DC internal resistance of a battery? and why does batteries have a internal resistance?

[@Sunilorkut]

Can I use 220 ohms 1/4 watt resistor for testing 9V and 1.5V batteries?? Sorry I am noob in this field and I have only these resistors with me ...

[@evahle]

Nice go-no-go test. Thank you!

[@asheqimran6238]

Do any multi-meters have a setting that adds resistance/load itself? So you wouldn't need to add it manually yourself?

[@knurlgnar24]

Some meters have a 'low Z' setting but that isn't enough current to test a battery. The best product for this is a battery load tester.

[@jaysanprogramming6818]

Brilliant! Thank you very much sir!

[@ClaudioMartella]

i have a 100k resistor. can i use that one on a 9 volt?

[@knurlgnar24]

Gar Suitor's comment gives more details on what a properly sized resistor would be for a 9V. Somewhere in the 100ohm to 1000ohm range is probably good enough for casual use.

[@ClaudioMartella]

@@knurlgnar24 thanks. What would happen if I used my 100k?

[@johnwilliamson6467]

I noticed your resistor is in parallel. I'd think you'd want that in series with your battery. Perhaps you could explain.

[@ddimin]

Ideal voltmeter has inifinite resistence, so it's effectively acts like an open circuit. So if you connect it in series (battery - resistor - voltmeter), it should show give you value around zero. (EDIT: ups, not zero, just slightly less than voltage on battery) You could use a current meter connected in series with resistor though, but it's less convinient.

[@jeffreydeutsch7336]

Dmitriy Afraid tou have it backwards. Standard meter resistance is 10megohms . putting another 100 ohms in series increases the infinitesimal load to an even smaller 10,000,100 ohms. The load goes across the battery. The smaller the resistance, the more current flows and the more you load the battery. You check with everything in parallel, not in series.

[@bouhannacheabdallah]

it is good explanation but it would be better if you added a sheet of the load resistance according to battery voltage and energy stored in amps

[@ravichandel8690]

1.5vdc battery on buzzer mode tested when +ve conected to +ve -ve to -ve no beep but as i changes the probe polarity there is a beep continues why

[@tonyferber3252]

I am looking at a "5% 50W 100 Ohms Wirewound Aluminium Housed Resistor Gold Tone" resistor, is this correct please?

[@knurlgnar24]

50W is overkill for what I show here. 5W is perfectly adequate and you could make do with 1W in most cases. Realistically, if you just want to test batteries a cheap battery load tester is the best solution, but if you're a geek like me then you'd rather have control of the load and understand exactly what is being tested with a known resistance.

[@tonyferber3252]

In the end I found out that the Powerex MH-C9000 will do what I need all in one, as well as the Eneloop batteries being the best ones to use, but thanks for the info, never would have found out about that otherwise!

[@radellaf]

p=v^2/r so >1W for a 9V and 1/4W for 1.5V. For a few seconds test a 1/2w is fine even for 9V. The Maha C9000 is great, though. Battery geek's dream for NiMH, and a 100-1000mA load for any kind of AA or AAA. Can do C & D with some home brew fixtures. You can also fully discharge a sample cell or few to see how a brand performs or to get an idea if your pack of 2011 batteries is really any good for your 300mA LED flashlight any more. Really, though, Eneloops are the things to use. Or, for emergency backup or extreme temperatures, Energizer lithium 1.7V cells. NOT for incandescent flashlights though. Or even cheap LED ones.

[@packrcch]

I never thought if this ! thank you!

[@Whale12321]

Thanks so much! Please would you advise, how to perform a similar test on a car battery? How many ohms resistance should I use? If a car battery is not adequate to crank a car engine anymore, should it be discarded, or can it fulfill another purpose (with a lighter load). Like running internal lighting (bulbs connected in series) during load shedding (not something I assume that affects Americans, but is a daily problem in South Africa with our fragile electrical network). Please forgive me, I'm not too clued up on the terminology. If you think your response is too basic or condescending, don't worry :) I'll be happy with what I get! Greetings from South Africa. Warren Hale

[@thembones12]

Car 12 Volt Battery: 12.7 Volt = 100% Charge, 12.32V =70%, 12.06 V= 50%, 11.75V = 30%, 11.58 V = 20% and 10.5 Volt = 0% charge (completely discharge)

[@BuffaloBetties]

A 100 ohm resistor for a 9 volt battery may be unrealistic. That means it would have to put out 810mw at 9V. Most 9V battery equipment is usually designed to only draw 20-80mw, pushing hard up to 100mw. Most 9V battery equipment will run fine when the voltage goes down to 6V as long as it can still put out around 13-15ma to generate around 80mw. The high frequency beeps produced by very efficient piezoelectric speakers in smoke alarms, don't really use much power to be very loud. A reading of 6-7 volts on it, with a 400-500 ohm resistor across it, may be good enough for the battery to still last a long time. Many rechargeable 9 volt batteries are actually only 7.2-7.5 volts new & fully charged. A good 9V battery may be rated at 200mah, but it was rated that way at around 20ma for 10 hours down to 6 volts, not 200ma for an hour at continuous 9 volts. A single 1.5 volt AAA cell (1.2 volts for rechargeable ones) may need to put out at least 40mw (33ma) in most apps they're used for. So a 36 ohm resistor would be best for 1.2-1.5 volt cells, or round up no higher than 50 ohms. I have a pocket LED light that draws over an amp off a single cell on it's brightest setting, but that's not typical usage for an AAA cell.

[@knurlgnar24]

Any 9V battery that is lower than 9.0V when new is bad - unless it is rechargeable which is often 7.2V but that is a special case. Do a search for 'Energizer 9V battery datasheet' and find the authoratative information on these batteries from a reputable manufacturer. Note that they are designed to operate up to 500mA, so a 100ohm resistor is perfectly appropriate. According to Energizer when discharged through a 100ohm resistor will take 7 hours for the battery to drain to 6.0V under load. That's a long time. I agree that a higher current would be better for AA batteries but then a higher power resistor is needed and a different one is needed for 9V, etc. 100 ohms is just simple. I find that it is very rare that a battery with good voltage fails and is not detectable with this 100 ohm trick.

[@danhle1032]

***** the lowest my resistors go in my hobby kits were 100ohms. I actually think higher resistors could make this test easier to distinguish the bad. i tested out a first set of batteries using 100ohms and didn't have much problems, the voltage decrease without a resistor vs with a resistor didn't drop so much (guessing i had decent batteries)....other times, the voltage reading kept going lower and lower, trickling down at a slower rate.. I think these were bad. taking the resistor out, these batteries would slowly rise back up

[@knurlgnar24]

danh le Sounds about right. Batteries that drop in voltage with a load (even a light 100ohm load) are weak and probably not worth using. Without the resistor the charge carriers will re-distribute themselves in the battery and the voltage will slowly rise up - but that higher voltage will only be present when the battery isn't being used which isn't very useful...

[@johnriver8125]

Hi, thanks for uploading your video! So following your suggestions I went to radio shack and bought a 100 ohm resister. But they had many different watt options at 100 ohms. I bought 1/4 watt 100 ohm resister, will that be ok? Hard to wrap my head around, they had 1/4, 1/2, 1, 10 watt options to choose from. Thanks for all your help on this!

[@knurlgnar24]

A 1/4 watt resistor will work on lower voltage batteries but will not withstand a 9V battery for long. If you only connect it for a few seconds and then let it cool you should be fine but a 1W or greater resistor would be preferred. Given that you already have a 1/4 watt resistor I would just use that. It should work fine as long as you only connect it for a brief time to those 9V batteries.

[@john4kc]

So you put the resister in parallel with the battery and not in series?

[@knurlgnar24]

The resistor is in parallel with the battery, yes. The idea is that the battery is loaded while being tested. If the resistor was in series with the meter it would do nothing.

[@spyrosvsli8567]

hello. how many watts is your resistor?

[@MrBigTexFyre]

My Extech 330 doesn't do it, but I have a cheapo Harbor Freight multimeter that actually has a setting to test batteries. For example, when you hook it up it shows around 4.0 mA for AA, AAA, etc and 25 mA for a 9V battery. How does it work? Is it placing the battery under a load? Very interesting that a cheapo would have it and a fairly decent multimeter wouldn't.

[@knurlgnar24]

Some of those cheap-o meters have functions that work very well indeed! Yes, your meter does put the battery under load and tests it properly. You can just use your Harbor Freight meter and ignore this video. :) As you said you can't use your Extech to do the same function even though it is likely a better product overall.

[@MrBigTexFyre]

***** Indeed my Harbor Freight dmm has become my official battery tester. Well at least I finally found a use for it.

[@Ameya274]

I'm gonna buy this multimeter....Mastech 830L Magnetic Electronic Level (16 cm)...you think it will check batteries right without need of attaching a 100 resistor!!

[@yamnjam]

It's so weird. I got the freebie cheapo multimeter at Harbor Freight a week ago since the previous one died from leaving it on accidentally. Then tonight I found some batteries lying around and wondered if I could test them with my new meter. Your video is the first one I watched, and if I hadn't read the comments, I wouldn't have known my meter can properly test them without having to go find a resistor. ( I have an AAS from TSTC but that was in the early 90's and went into another career) and I realized I forgot how to read the colored stripes on the resistors. If you don't use it, you lose it. Oh well. But it's so nice to find the perfect answers to my situation in the very first video/comments. I won't be testing any transistors or diodes anytime soon but this meter apparently will test those too. Great video thanks for explaining it to all of us.

[@jeffreydeutsch7336]

The better low cost testers use a different load resistor for different cells. A D-cell generally will be used in a higher current demand device than a AAA. To do it right, one value resistor does no fit all. Even then, some cells are used at higher or lower than the average consumption for the type. A variable test load to approximate the working load is best. That power resistor's wattage is super overkill

[@JazzDigits]

If you do not know the value of resistance, use the multimeter set to read Ohms to test the value of the resistor.

[@Petruccio1881]

Hi, thanks for video. I've got one question: I'd like to test my 18650 rechargeable 3.7v battery, is it ok if use 100 ohm resistor for it?

[@Milesco]

100 ohms is too high of a resistance to get much (current or information) out of a battery, especially a large-ish one like a 18650. I would use no higher than a 5-ohm resistor.

[@janslezacek62]

So, how many minimum volts is needed to run an appliance?

[@jeffreydeutsch7336]

John Slezi It varies with the appliance. It also depends on the load. with a heavy load the battery may drop too low to run it. with a light load the voltage stays higher.

[@woreoutdavinciconstruction4060]

the kind you plug in a wall plug ? about 98 min..and it should have 115 volts