A simple way to test the charge level on alkaline batteries (2015) [video](youtube.com)
youtube.com
A simple way to test the charge level on alkaline batteries (2015) [video]
https://www.youtube.com/watch?v=nwfFBUVxpac
122 comments
This is an actual life pro tip! How reliable is this method?
I've been doing it this way for years, and it works pretty reliably as long as they're alkaline batteries.
Since decent rechargeable AA and AAA batteries came out (Eneloop was the first), I've been replacing a lot with those though because (at least in my experience) the rechargeables seem much less prone to leaking and corroding whatever device they've been left in.
Since decent rechargeable AA and AAA batteries came out (Eneloop was the first), I've been replacing a lot with those though because (at least in my experience) the rechargeables seem much less prone to leaking and corroding whatever device they've been left in.
Eneloop are fantastic! IKEA carries their branded version with them, for half price, along with their high-density version. I got a bunch of IKEA rechargables and I'm sorted.
Get a good smart charger that can do a charge/discharge/charge cycle every once in a while!
Ah, my hobby is RC planes, so I have tons of chargers. I'll have one cycle them, thanks!
Very reliable for telling brand new vs 100% depleted batteries.
But if you want to separate 1.4 volt batteries from 1.5 volt batteries, use a multimeter.
But if you want to separate 1.4 volt batteries from 1.5 volt batteries, use a multimeter.
I found that the voltage does not say much, at least not for a general type. Just put your multimeter in 20 A mode and make sure you connect the red cable to A terminal. Use it to shortly short circuit the batt. A good (charged) battery delivers >8A
Or the $1.50 tester from Ebay.
Yes - but why when you can get a multimeter for $10 (incl shipping)? So much more useful for so little extra money (since those $1.49 battery testers on ebay cost $2.50 to ship anyways, and they take 20 days to show up).
Because it's much simpler to have a 1.50 tester sitting with the batteries that's fixed function than dealing with the leads, the proper setting, finding the right band of numbers if it's analog. There's something to be said for fixed function.
A multimeter doesn't put any load on the battery.
A (decent) tester will have an appropriate load for the type of battery of about 0.05 to 0.1C, so for a 2200 mAh AA NiMH, about 110 mA to 200 mA. 10 - 12 ohm resistor for 1.2V nominal.
This shows you the cell's internal resistance, an increase of which is a sign of impending doom for a battery.
If you use your batteries at high currents, test at those currents.
A (decent) tester will have an appropriate load for the type of battery of about 0.05 to 0.1C, so for a 2200 mAh AA NiMH, about 110 mA to 200 mA. 10 - 12 ohm resistor for 1.2V nominal.
This shows you the cell's internal resistance, an increase of which is a sign of impending doom for a battery.
If you use your batteries at high currents, test at those currents.
Sure - but a multimeter also doesn't require the battery to be inserted into it - you can test the voltage while the battery is under load in most devices.
Not saying you can't buy a really good dedicated battery tester if that's what you want - but that dolla-fiddy version from ebay ain't gonna be it :)
Not saying you can't buy a really good dedicated battery tester if that's what you want - but that dolla-fiddy version from ebay ain't gonna be it :)
It's a little more granular than that. At minimum, you can tell full from half full from mostly empty. But yeah, not 80% vs 70% or anything like that.
doesn't work with cheapo zinc-carbon batteries. You can normally tell those though because they are lighter and if you squeeze them firmly they dent.
[deleted]
The explanation as published in the Journal of Materials Chemistry:
"As an alkaline battery is discharged, the anode undergoes oxidation from Zn to ZnO. ... The battery most likely begins to bounce because of displacement of water by solid ZnO bridges between particles of zinc in the gel. These bridges provide less impeding and attenuating paths for pressure waves, in turn making the battery bouncier."
-- The relationship between coefficient of restitution and state of charge of zinc alkaline primary LR6 batteries (same paper already mentioned by others)
"As an alkaline battery is discharged, the anode undergoes oxidation from Zn to ZnO. ... The battery most likely begins to bounce because of displacement of water by solid ZnO bridges between particles of zinc in the gel. These bridges provide less impeding and attenuating paths for pressure waves, in turn making the battery bouncier."
-- The relationship between coefficient of restitution and state of charge of zinc alkaline primary LR6 batteries (same paper already mentioned by others)
Man, I remember Kipkay... I actually discovered him on Metacafe (no longer a thing). My teenage mind was blown away by how someone could know so much about electronics/gadgets so I emailed him asking what his background is.
I don't quite remember his exact reply but it was something a long the lines of "I'm just a regular dude who's interested in this stuff".
I don't quite remember his exact reply but it was something a long the lines of "I'm just a regular dude who's interested in this stuff".
I see that the two batteries demonstrated were from different manufacturers. I've heard this claim before, but is the difference so pronounced when using batteries from the same manufacturer?
Also, the dead battery is at 0.6 volts - I've never seen a battery that dead. Is the bounce effect so pronounced when a battery is at 1.1 volts, which is a far more typical dead battery voltage?
Also, the dead battery is at 0.6 volts - I've never seen a battery that dead. Is the bounce effect so pronounced when a battery is at 1.1 volts, which is a far more typical dead battery voltage?
EEVBlog did the same test with matching brands and discharged to 1.2 V unloaded/0.8V loaded https://www.youtube.com/watch?v=PRf9JTg3QwA
An even better test would be to test the same battery before discharge and after.
Or perhaps, buy six identical batteries, labeled 1-6; randomly charge them to two different levels (100% and 60%), three each, noting down which was which; then hand them to another set of people, who have only seen the numbers, and bounce each of them, to see how reliably they can tell the difference.
Only works with alkaline non-rechargeable batteries, but apart from that, yeah.
Which is arguably the most common type of AA sold.
Or even better, buy six million identical batteries, label them, discharge them randomly, run some rudimentary tests, and announce you’ve identified a room-temperature superconductor!
…Too soon?
…Too soon?
Yeah that’s basic science.
No that would be far far worse test than having 2 equivalent batteries, and discharging one of them. First, it is easier to measure differences than absolute values (by eye, but even with precise equipment), second it automatically cancels out the affects of temperature, humidity, pressure etc. (Okay, you know that these things doesn't matter in this experiment, still.)
Well, it should be relatively easy to try to reproduce the experiment... but yes, I agree that a battery will be considered "dead" when the device it was powering stops working with the provided voltage, and 0.6 volts is likely far below that voltage (except maybe for traditional flashlights with incandescent bulbs which get dimmer and dimmer, but will probably still work?).
I use this all the time with the bulk batteries from Costco. My gut also says the bounce effect is a little too sensitive, as I've had batteries have a good bounce even when the device they're is still able to pull some juice out.
But a fresh battery will 100% not bounce. It's the simplest thing to do when you're changing the batteries in something and you got the old/new batteries mixed up.
But a fresh battery will 100% not bounce. It's the simplest thing to do when you're changing the batteries in something and you got the old/new batteries mixed up.
i am an audiologist. this is my go-to method for checking hearing aid batteries on the fly, especially as it lets me work a bit messily.. for better or worse, i now have a habit of ripping fresh batts out out of a packet, without immediately disposing of the old ones i have removed from an aid, while my attention is focused on programming it (older aids often interface using a cable connected to a programming 'pill' which supplies power and data through an empty battery cavity... so i can be putting batteries in and out and programming cables in an out, multiple times in a session with a client... anyhow..) i no longer need to pay attention as to which battery is which, as i just pick up both together and drop them from about a 15cm height.. the old one bounces jauntily away, while the new one stops dead with zero bounce. it is a super accurate trick and the information never fails to astound clients.. it surprised me when i learnt it from an old salt colleague and it surprises me more that it is not common knowledge.. especially amongst my workmates.
Hearing aids mostly use zinc-air batteries.
I believe your trick works for a different reason - zinc-air batteries get heavier as they discharge since they absorb water from the air.
I believe your trick works for a different reason - zinc-air batteries get heavier as they discharge since they absorb water from the air.
thanks.. i really know nothing apart from that i enjoy doing it with hearing aid batteries myself.. there is something really satisfying watching the no-bounce battery. as for the reason, i always presumed it was because they take in oxygen. i can't find anything on the weight of discharged vs charged zinc air batteries... but they have always felt a teeny tiny bit lighter when used (i have no evidence!) and i am not sure about your water supposition... i know they -can- swell with water if it is too humid for example, but generally, don't they expel water as they discharge...? "Zn–air battery uses oxygen from the air, and hence, air holes in it are kept open for cell operation. Therefore, loss of water by evaporation through the holes is inevitable. When the water is depleted, the battery ceases to operate. There are two water consumption routes in Zn-air batteries, namely, active path (electrolysis) and passive path (evaporation and corrosion)." source: https://www.jecst.org/journal/view.php?number=300
regardless.. here is a nice video of the effect in hearing aid batteries.. https://www.facebook.com/BMHearing/videos/2037506353043179/ sorry the only link i can find worth sharing is on FB.
regardless.. here is a nice video of the effect in hearing aid batteries.. https://www.facebook.com/BMHearing/videos/2037506353043179/ sorry the only link i can find worth sharing is on FB.
Why are people still using alkaline batteries?
I have a bunch of Enloops which I pop into everything. Mice, keyboards, game controllers, TV remotes, soap dispensers, etc etc. I also have a bunch sitting in chargers, so I can quickly swap an empty battery with a full one whenever I need to. As far as I can tell, the ones I first bought in ~2015 are still going strong.
I do explicitly seek out products which take AAs as opposed to using internal rechargeable batteries, because I can swap out my Enloops in less than a minute, versus plugging the product in and waiting hours for it to finish charging!
I have a bunch of Enloops which I pop into everything. Mice, keyboards, game controllers, TV remotes, soap dispensers, etc etc. I also have a bunch sitting in chargers, so I can quickly swap an empty battery with a full one whenever I need to. As far as I can tell, the ones I first bought in ~2015 are still going strong.
I do explicitly seek out products which take AAs as opposed to using internal rechargeable batteries, because I can swap out my Enloops in less than a minute, versus plugging the product in and waiting hours for it to finish charging!
One thing I have noticed is that devices with built in voltage sensors will oftentimes read even fully charged rechargeables as low battery, which can be annoying. This has happened with devices as new as a Roku remote and as old as a Game Boy Advance. It may vary from battery brand to brand, but I just use the AmazonBasics.
The common rechargeable battery chemistries are 1.2 V (NiCd, NiMH), but a normal alkaline battery is 1.5 V. It usually works OK because the alkalines drop voltage quickly and devices are designed to operate in a lower range. If you can fit it in somehow, it something makes sense to add an extra battery. E.g. 5 rechargeables has the same voltage as 4 alkalines (6V).
Yeah the ideal replacement would be a 14500 or 18650 but they run at 3.7v so they would break a lot of electronics meant for alkalines. There are also CR123A batteries which are lithium primary cells and are much better for low temp applications or for long storage times. They also have a matching 16340 rechargable type which has a similar voltage.
The problem is, the average consumer is too dumb to be able to understand the difference, even the enthusiast flashlight/dive light/firearm light people have some holdouts who insist everything should just be alkalyne because they don't understand any of this.
The problem is, the average consumer is too dumb to be able to understand the difference, even the enthusiast flashlight/dive light/firearm light people have some holdouts who insist everything should just be alkalyne because they don't understand any of this.
They make AA size batteries that have a lithium battery inside along with built in voltage dropping, protection, and charge circuitry. They are cheap.
Those are rough because the buck regulator is ~80-90% efficient and takes up space that would otherwise be battery. Any advantage they have over the NiMH cells is marginal at best, but they at least theoretically have a better discharge curve for stuff that's very voltage sensitive.
A very big problem with nicd is that if you charge them now and use them after weeks, a very big chunk of the charge has been lost.
The rate of loss of charge while sitting is related to the total capacity of the NiMH battery. More capacity, faster self-discharge. Lower capacity, lower self-discharge. The 2400 mAh Eneloops lose about 15% a year, compared to 1% a day for the high capacity EBLs you'll find on Amazon.
it's because rechargable AA is not a proper AA (standard) battery. It's an "all-what-we-could-fit-in-such-a-small-compartment" battery.
[deleted]
I mostly agree, except for TV remotes. My experience is that the cheap off brand batteries that came with the remote will likely last for the entire lifetime of the device, a decade or more. Replacing them with rechargeables is a waste and a hassle since even Eneloops have a self discharge curve that means you have to pop the batteries out and top them off every few years.
It's crazy how to batteries that come with electronics seem to last forever isn't it?
I would like someone to explain this. They are often not even alkaline. Once you replace them, they never last as long as the original.
I use plenty of rechargeable batteries, but I also use disposables. Disposable batteries hold significantly more charge and sometimes that matters.
For instance my smart lock if I fill with rechargeables I find myself having to call a locksmith. I think that might be not only due to the lower capacity but that it holds closer to voltage until completely drained so it prevents the lock from giving me adequate warning.
I also have a property that’s an AirBnB and I’m sure those tenants are animals, so I leave the disposables for things like remotes. They would just dispose of rechargeables if I let them.
For instance my smart lock if I fill with rechargeables I find myself having to call a locksmith. I think that might be not only due to the lower capacity but that it holds closer to voltage until completely drained so it prevents the lock from giving me adequate warning.
I also have a property that’s an AirBnB and I’m sure those tenants are animals, so I leave the disposables for things like remotes. They would just dispose of rechargeables if I let them.
> Disposable batteries hold significantly more charge and sometimes that matters.
Not really true but also not wrong. Disposable batteries tend to be on par with rechargeable when it comes to charge. Disposable AA 2850mAh [1] Rechargeable 2000mAh [2]
What you are (likely) experiencing is that rechargeable batteries tend to have much higher self discharge rates than disposables. The end result is the rechargeable feel like they have less capacity as they seem to last for a shorter period of time. Further, the lower voltage tends to also push you to need to recharge them because your devices fail to work at the lower voltages.
The dastardly part of rechargeable is you can get like 3500mAh AA but you shouldn't because those tend to have absurdly high self discharge rates. (AFAIK) The enloop batteries tend to be the best when it comes to self discharge, but at the cost of lower total capacity.
[1] https://www.supplyhog.com/c/electrical/batteries-flashlights...
[2] https://www.amazon.com/Panasonic-BK-3MCCA4BA-eneloop-Pre-Cha...
Not really true but also not wrong. Disposable batteries tend to be on par with rechargeable when it comes to charge. Disposable AA 2850mAh [1] Rechargeable 2000mAh [2]
What you are (likely) experiencing is that rechargeable batteries tend to have much higher self discharge rates than disposables. The end result is the rechargeable feel like they have less capacity as they seem to last for a shorter period of time. Further, the lower voltage tends to also push you to need to recharge them because your devices fail to work at the lower voltages.
The dastardly part of rechargeable is you can get like 3500mAh AA but you shouldn't because those tend to have absurdly high self discharge rates. (AFAIK) The enloop batteries tend to be the best when it comes to self discharge, but at the cost of lower total capacity.
[1] https://www.supplyhog.com/c/electrical/batteries-flashlights...
[2] https://www.amazon.com/Panasonic-BK-3MCCA4BA-eneloop-Pre-Cha...
Ummm 2850 is significantly higher than 2000. 40% is significant.
eneloop battery is not a proper AA battery. Proper alkaline battery does 1.7V when charged, while eneloop does max. 1.5V (usually 1.45V and deteriorate over time). Some electronics which depend on this, will malfunction or work very shortly on rechargable eneloop or similar.
this chart https://www.prosoundweb.com/images/uploads/Fig1CTA_BatteryGr... shows max 1.6 but I witnessed 1.7 on full alkaline and 1.45V on eneloop
this chart https://www.prosoundweb.com/images/uploads/Fig1CTA_BatteryGr... shows max 1.6 but I witnessed 1.7 on full alkaline and 1.45V on eneloop
> Some electronics which depend on this, will malfunction or work very shortly on rechargable eneloop or similar.
Take a closer look at the graph you linked to. Those devices will also stop working very shortly on alkaline batteries. The voltage as a function of discharge capacity curve for alkaline falls below Eneloop about 1/3 of the way in.
That means that if the device can work at alkaline voltage after it has used about 1/3 of the alkaline capacity it will also work as long or longer with an Eneloop of the same total capacity.
The alkaline curve voltages falls below max Eneloop voltage after about 10% discharge. That means a device that actually needs a voltage above Eneloop voltage was poorly designed. It is either going to be ridiculously wasteful on alkaline batteries (unless the user realizes that when the device conks out due to low batter the batteries actually still have 90% capacity remaining and uses those batteries in some other device designed by a competent engineer instead of throwing them out as dead) or should have been using something other than AA batteries such as CR123A that will be above 1.4 V throughout most of its discharge curve.
The only problem you should see in a well designed device that was designed for AA but for which the designers did not take into account rechargeable vs primary is that the battery indicator might not be as accurate on rechargeable. That's because simple batter indicators use the voltage to estimate where they are on discharge curve.
If this assumes an alkaline discharge curve then with a rechargeable it will think fresh batteries are at about 90%, which will rapidly fall to around 75%, and then think it is barely declining for a long time until the batteries are actually at about 10%, and then it will rapidly go down.
Take a closer look at the graph you linked to. Those devices will also stop working very shortly on alkaline batteries. The voltage as a function of discharge capacity curve for alkaline falls below Eneloop about 1/3 of the way in.
That means that if the device can work at alkaline voltage after it has used about 1/3 of the alkaline capacity it will also work as long or longer with an Eneloop of the same total capacity.
The alkaline curve voltages falls below max Eneloop voltage after about 10% discharge. That means a device that actually needs a voltage above Eneloop voltage was poorly designed. It is either going to be ridiculously wasteful on alkaline batteries (unless the user realizes that when the device conks out due to low batter the batteries actually still have 90% capacity remaining and uses those batteries in some other device designed by a competent engineer instead of throwing them out as dead) or should have been using something other than AA batteries such as CR123A that will be above 1.4 V throughout most of its discharge curve.
The only problem you should see in a well designed device that was designed for AA but for which the designers did not take into account rechargeable vs primary is that the battery indicator might not be as accurate on rechargeable. That's because simple batter indicators use the voltage to estimate where they are on discharge curve.
If this assumes an alkaline discharge curve then with a rechargeable it will think fresh batteries are at about 90%, which will rapidly fall to around 75%, and then think it is barely declining for a long time until the batteries are actually at about 10%, and then it will rapidly go down.
> If this assumes an alkaline discharge curve then with a rechargeable it will think fresh batteries are at about 90%, which will rapidly fall to around 75%, and then think it is barely declining for a long time until the batteries are actually at about 10%, and then it will rapidly go down.
It's a bit worse than that in my experience. Devices with low-battery warnings seem to basically show the warnings perpetually, never on truly fresh batteries but reasonably soon afterwards. In actuality, the batteries will last for months past that point.
If the curve was like you describe, I'd expect to see low battery warnings less, not more, frequently with rechargeables than disposables.
Still not worth switching away from rechargeable, although I wish I could silence the warnings.
It's a bit worse than that in my experience. Devices with low-battery warnings seem to basically show the warnings perpetually, never on truly fresh batteries but reasonably soon afterwards. In actuality, the batteries will last for months past that point.
If the curve was like you describe, I'd expect to see low battery warnings less, not more, frequently with rechargeables than disposables.
Still not worth switching away from rechargeable, although I wish I could silence the warnings.
The only good reason for a disposable battery is if the power draw is somehow that a rechargeable would have expired from calendar aging by the time the disposable is dead. Very high efficiency RTCs, emergency backups never expected to be used, highly specialized devices used for only a few minutes a year, etc.
I do really think that we need a better rechargeable battery standard though. If something is big enough for it, 18650s are close to perfect, but not much is.
There's enough devices like GoPros which have swappable batteries and third-party availability, and so are de facto standards, why don't people just design their stuff to use one of those?
I do really think that we need a better rechargeable battery standard though. If something is big enough for it, 18650s are close to perfect, but not much is.
There's enough devices like GoPros which have swappable batteries and third-party availability, and so are de facto standards, why don't people just design their stuff to use one of those?
I started making the transition, and then I realized that it makes me think of each eneloop as a device that I need to think about and maintain. How much life does it have left in it? How can I measure that? How can I remember which is which?
It's been a few years, so I couldn't tell you exactly what happened that made me think this way. But some devices worked with brand new eneloops but not as well with older ones.
Also, my camera flash dies (e.g. drops from usable to unusable) much more rapidly with eneloops. I missed a few one-of-a-kind photo ops and then decided the flash only uses alkalines now.
It's been a few years, so I couldn't tell you exactly what happened that made me think this way. But some devices worked with brand new eneloops but not as well with older ones.
Also, my camera flash dies (e.g. drops from usable to unusable) much more rapidly with eneloops. I missed a few one-of-a-kind photo ops and then decided the flash only uses alkalines now.
People see batteries as "cheap and disposable". The price tag of $15 for 4 batteries is a one-time hit that most people in the US* don't want to take. You and I both know they will save money over time, and yes, it's much better for the environment to reuse, but that is why.
*I come from a non-US country, and was brought up using rechargeable batteries. I have lived here for 10 years and I have not seen a single rechargeable AA at any point.
*I come from a non-US country, and was brought up using rechargeable batteries. I have lived here for 10 years and I have not seen a single rechargeable AA at any point.
Last time I looked into it end-to-end, it seemed like a NiMH cell would need to be reused like 500 times in order for it to actually be an improvement for the environment over one-time-use alkaline. NiMH is better than NiCd but still relatively nasty.
Because I'm pretty certain most people don't even realise they exist and it's easier to grab some from the local shop when your remote dies.
I think part of it is that most people probably think that the cost of the useable energy in a battery is a significant amount of the cost of the battery. And so they expect that the cost to recharge a rechargeable battery is going to be about the same cost as buying a new disposable battery (or more...the disposable battery maker will be getting their electricity at industrial rates which are usually quite a bit lower than residential rates).
And so they think that what you are paying for when you spend 6x as much to buy a rechargeable battery is mostly the convenience of not having to go the store to buy new batteries.
But since batteries are sold at the grocery store and at convenience stores and have something like a 10 year shelf life it isn't actually inconvenient to just keep a small stock on hand and replenish them as needed when buying groceries, except maybe for the exceptionally forgetful or disorganized.
In fact batteries are a very expensive way to buy energy.
Take a 2800 mAh AA alkaline battery. At a nominal 1.5 V that's 4200 mWh of energy, or 0.0042 kWh. If you live in someplace with very high residential electricity rates such as Denmark or Germany that's about $0.0023 worth of electricity.
In the US, where electricity is a bit cheaper, for the average consumer it would be about $0.0007. It would take 1400 of those batteries to get the same amount of electricity that would cost you $1 when taken from a wall socket.
The result is that for most people they will save money with rechargeable batteries. The exceptions will mostly be people who have very few devices that use AA or AAA batteries. They might go through batteries at a low enough rate that the savings each time they need to change batteries isn't enough to overcome the upfront cost of the rechargeable batteries and a charger.
And so they think that what you are paying for when you spend 6x as much to buy a rechargeable battery is mostly the convenience of not having to go the store to buy new batteries.
But since batteries are sold at the grocery store and at convenience stores and have something like a 10 year shelf life it isn't actually inconvenient to just keep a small stock on hand and replenish them as needed when buying groceries, except maybe for the exceptionally forgetful or disorganized.
In fact batteries are a very expensive way to buy energy.
Take a 2800 mAh AA alkaline battery. At a nominal 1.5 V that's 4200 mWh of energy, or 0.0042 kWh. If you live in someplace with very high residential electricity rates such as Denmark or Germany that's about $0.0023 worth of electricity.
In the US, where electricity is a bit cheaper, for the average consumer it would be about $0.0007. It would take 1400 of those batteries to get the same amount of electricity that would cost you $1 when taken from a wall socket.
The result is that for most people they will save money with rechargeable batteries. The exceptions will mostly be people who have very few devices that use AA or AAA batteries. They might go through batteries at a low enough rate that the savings each time they need to change batteries isn't enough to overcome the upfront cost of the rechargeable batteries and a charger.
we have dozens and dozens of AA batteries here, like everyone else. and your suggestion "why aren't you using rechargables" is compelling, buying a ton of these and just having them in a charger seems like a good idea. So what are the little things in my mind making me hesitate?
1. how long they will continue to remain rechargable; and if they begin to hold less and less of a charge. if they are still recharging fine for you after 8 years, that seems pretty good.
2. what happens if the rechargable battery is left inside a forgotten toy or device for 7 years? if I find it 7 years later, is it a leaky mess or still viable? this is a big reason "AA's are disposable anyway, who cares" is appealing - we have forgotten batteries all the time. if we forget about a toy and our $3.50/each batteries are ruined we could be buying a lot of these pricey batteries
3. how long do they last on a full charge? if use them for camp lights are we going to run out of light after a day ?
1. how long they will continue to remain rechargable; and if they begin to hold less and less of a charge. if they are still recharging fine for you after 8 years, that seems pretty good.
2. what happens if the rechargable battery is left inside a forgotten toy or device for 7 years? if I find it 7 years later, is it a leaky mess or still viable? this is a big reason "AA's are disposable anyway, who cares" is appealing - we have forgotten batteries all the time. if we forget about a toy and our $3.50/each batteries are ruined we could be buying a lot of these pricey batteries
3. how long do they last on a full charge? if use them for camp lights are we going to run out of light after a day ?
> 1. how long they will continue to remain rechargable; and if they begin to hold less and less of a charge. if they are still recharging fine for you after 8 years, that seems pretty good.
My first generation AA Eneloops, which I bought sometime in 2008 or earlier (I know this because I bought them at Circuit City which closed in March 2009 and I bought them at least several months before then), are still working fine.
Their specs say minimum 1900 mAh capacity, typical 2000 mAh. Most of them have fallen to slightly below that, in the 1850-1900 mAh range.
My first generation AAA Eneloops, purchased at the same time, are all in the 790-840 mAh range. Spec is min 750 typical 800.
My 4th generation AA Eneloops, bought almost 9 years ago (their 9th anniversary is in 3 days), which I've used more heavily than the first generation ones because they have a lower self discharge (1st gen is 80% after one year, 4th gen is 90%/80%/70% after 1/3/5 years), are mostly still in the 1900-2000 range, with one at 1880 and one at 2055.
I've had 2 (out of 21) first gen AAs and 4 (out of 16) first gen AAAs die. None of my 4th gen AAs have died. By "die" I mean my PowerEx MH-C9000 charger says they fail an impedence check that it does before charging and refused to charge them, and no attempts to revive them worked.
> 2. what happens if the rechargable battery is left inside a forgotten toy or device for 7 years?
I don't know but someday I'll maybe find out, because I have 3 first gen AAs that I've lost track of. They are probably in something in my junk pile, like a remote for a VCR.
My first generation AA Eneloops, which I bought sometime in 2008 or earlier (I know this because I bought them at Circuit City which closed in March 2009 and I bought them at least several months before then), are still working fine.
Their specs say minimum 1900 mAh capacity, typical 2000 mAh. Most of them have fallen to slightly below that, in the 1850-1900 mAh range.
My first generation AAA Eneloops, purchased at the same time, are all in the 790-840 mAh range. Spec is min 750 typical 800.
My 4th generation AA Eneloops, bought almost 9 years ago (their 9th anniversary is in 3 days), which I've used more heavily than the first generation ones because they have a lower self discharge (1st gen is 80% after one year, 4th gen is 90%/80%/70% after 1/3/5 years), are mostly still in the 1900-2000 range, with one at 1880 and one at 2055.
I've had 2 (out of 21) first gen AAs and 4 (out of 16) first gen AAAs die. None of my 4th gen AAs have died. By "die" I mean my PowerEx MH-C9000 charger says they fail an impedence check that it does before charging and refused to charge them, and no attempts to revive them worked.
> 2. what happens if the rechargable battery is left inside a forgotten toy or device for 7 years?
I don't know but someday I'll maybe find out, because I have 3 first gen AAs that I've lost track of. They are probably in something in my junk pile, like a remote for a VCR.
It's unnerving to see someone keeping highly accurate records of mundane things such as battery purchase dates, nominal capacities, and charger model numbers.
I need to ask, do you work with these things daily, or do you just have an exceptional memory?
I need to ask, do you work with these things daily, or do you just have an exceptional memory?
I got the charger number by glancing at the manual, which I have as a PDF in my "manuals" folder.
For the purchase dates for the 1st generation batteries I simply remembered that I bought them at Circuit City and that it was at least a few months before Circuit City went out of business, so a quick Googling gavee me that it was in 2008 or earlier.
For the 4th generation batteries I bought them at Amazon so simply have to type "eneloop" in the purchase history search and it shows me.
The charger includes a "Refresh & Analyze Mode" that rechargers the battery, rests for one hour, discharges the battery (and notes the capacity), rests for one hour, and the recharges the battery.
They recommend doing this every 10 cycles. I don't strictly follow that schedule, but I do occasionally do a refresh/analyze to see if a battery has degraded and needs to be retired. And so I have a spreadsheet to record the last refresh/analyze and the result.
Here's what columns are in that spreadsheet:
Number: I've written a number on each battery with a Sharpie so I can tell them apart.
Bin: when a battery is not in use or in the charger, it is in a small numbered storage bin. This is the number of that bin.
R/A: the date of the last refresh/analyze.
Years ago: a computed column that is simply the difference between now and the R/A date, in years
Capacity: the capacity found during the last R/A.
Prior Capacity: the capacity found during the previous R/A, so I can see if it has gone down much.
Total cycles: how many times I've charged the battery.
Cycles before last R/A: how many times the batter was charged before the most recent R/A.
Location: what the battery is in, if it is not in the charger or its assigned bin. Example values are "bathroom scale" and "TV remote".
Date deployed: if the battery is in a device this is the date it went in. Blank if it is not in use.
Days in use: the difference between the current date and the date deployed column, in days.
Charged: for batteries in their bins this is the date they were last charge.
Ago: Difference in days between now and the date in the "Charged" column.
That sounds like it might take a lot of work, but it doesn't. Let's say the batteries are getting weak in the TV remote, which uses two AA batteries. I take a quick look at the spreadsheet, looking at the "Charged", "Ago", and "Capacity" columns to pick a couple of batteries that aren't too far apart in capacity, and were last charged not too far apart. I enter "TV remote" and today's date in their "Location" and "Date deployed" columns, and clear their "Charged" columns, and go put them in the remote. (If the remote's batteries are still good enough that I don't actually need to change them immediately I might first put the replacements in the charger to top them up).
For the batteries that come out of the remote I clear their "Location" and "Date deployed" columns, add one to the "Total cycles" column, and stick them in the charger.
When I noticed they are fully charged, I put the date in the "Charged" column, and put them in their bins.
I've got some other things on the battery spreadsheet not directly concerning rechargeable batteries.
For some devices I track battery life. That too is pretty simple. Each such device has a table that consists of two columns:
Date: the date of a battery change
"Used For" or "Years Used": how long those batteries lasted. For the last row in the table, that is how long the batteries have been in use so far. For any prior rows it is how long it was until the next battery change. "Used For" if in days, "Years Used" if in years.
For these tables they have a label above with the name of the device, and a subheader saying what kind of battery they take. For example here is the table for my car:
For example I can see from the iPhone X's table that it had 100% capacity when I bought it on 2018-07-03. By 2021-04-30 it was down to 96.3% and had 189 cycles. By 2022-12-19 it was down to 92.2% and had 299 cycles. I then had the battery replaced, and after that on 2022-12-21 it was at 102.0% (!) and 0 cycles.
Finally, for things that use batteries that are not AA or AAA or car batteries or UPS batteries I have a section that simply lists which device uses which battery type. For example I can see from this that I have these things that use CR2032: HP-15C Limited Edition, Casio FX-702P, guitar case humidity meter, an old tuner that I don't use anymore, and the remotes for my garage door openers.
This comes in handy when buying new things. Suppose I'm deciding between two things and see that one uses a CR2032 and one uses a CR2020. A glance at my spreadsheet tells me that the only thing I currently have that takes CR2020 is an old Casio watch. Since I haven't used that watch in decades, but do have things I currently use that use CR2032 (humidity meter, garage door openers, and occasionally the HP-15C) that will be a point in favor of getting the device that uses the CR2032.
For the purchase dates for the 1st generation batteries I simply remembered that I bought them at Circuit City and that it was at least a few months before Circuit City went out of business, so a quick Googling gavee me that it was in 2008 or earlier.
For the 4th generation batteries I bought them at Amazon so simply have to type "eneloop" in the purchase history search and it shows me.
The charger includes a "Refresh & Analyze Mode" that rechargers the battery, rests for one hour, discharges the battery (and notes the capacity), rests for one hour, and the recharges the battery.
They recommend doing this every 10 cycles. I don't strictly follow that schedule, but I do occasionally do a refresh/analyze to see if a battery has degraded and needs to be retired. And so I have a spreadsheet to record the last refresh/analyze and the result.
Here's what columns are in that spreadsheet:
Number: I've written a number on each battery with a Sharpie so I can tell them apart.
Bin: when a battery is not in use or in the charger, it is in a small numbered storage bin. This is the number of that bin.
R/A: the date of the last refresh/analyze.
Years ago: a computed column that is simply the difference between now and the R/A date, in years
Capacity: the capacity found during the last R/A.
Prior Capacity: the capacity found during the previous R/A, so I can see if it has gone down much.
Total cycles: how many times I've charged the battery.
Cycles before last R/A: how many times the batter was charged before the most recent R/A.
Location: what the battery is in, if it is not in the charger or its assigned bin. Example values are "bathroom scale" and "TV remote".
Date deployed: if the battery is in a device this is the date it went in. Blank if it is not in use.
Days in use: the difference between the current date and the date deployed column, in days.
Charged: for batteries in their bins this is the date they were last charge.
Ago: Difference in days between now and the date in the "Charged" column.
That sounds like it might take a lot of work, but it doesn't. Let's say the batteries are getting weak in the TV remote, which uses two AA batteries. I take a quick look at the spreadsheet, looking at the "Charged", "Ago", and "Capacity" columns to pick a couple of batteries that aren't too far apart in capacity, and were last charged not too far apart. I enter "TV remote" and today's date in their "Location" and "Date deployed" columns, and clear their "Charged" columns, and go put them in the remote. (If the remote's batteries are still good enough that I don't actually need to change them immediately I might first put the replacements in the charger to top them up).
For the batteries that come out of the remote I clear their "Location" and "Date deployed" columns, add one to the "Total cycles" column, and stick them in the charger.
When I noticed they are fully charged, I put the date in the "Charged" column, and put them in their bins.
I've got some other things on the battery spreadsheet not directly concerning rechargeable batteries.
For some devices I track battery life. That too is pretty simple. Each such device has a table that consists of two columns:
Date: the date of a battery change
"Used For" or "Years Used": how long those batteries lasted. For the last row in the table, that is how long the batteries have been in use so far. For any prior rows it is how long it was until the next battery change. "Used For" if in days, "Years Used" if in years.
For these tables they have a label above with the name of the device, and a subheader saying what kind of battery they take. For example here is the table for my car:
2006 Honda CR-V
group size 51R
---------------
Date
2013-12-08 4.0
2017-12-23 5.6
For example I can see from the iPhone X's table that it had 100% capacity when I bought it on 2018-07-03. By 2021-04-30 it was down to 96.3% and had 189 cycles. By 2022-12-19 it was down to 92.2% and had 299 cycles. I then had the battery replaced, and after that on 2022-12-21 it was at 102.0% (!) and 0 cycles.
Finally, for things that use batteries that are not AA or AAA or car batteries or UPS batteries I have a section that simply lists which device uses which battery type. For example I can see from this that I have these things that use CR2032: HP-15C Limited Edition, Casio FX-702P, guitar case humidity meter, an old tuner that I don't use anymore, and the remotes for my garage door openers.
This comes in handy when buying new things. Suppose I'm deciding between two things and see that one uses a CR2032 and one uses a CR2020. A glance at my spreadsheet tells me that the only thing I currently have that takes CR2020 is an old Casio watch. Since I haven't used that watch in decades, but do have things I currently use that use CR2032 (humidity meter, garage door openers, and occasionally the HP-15C) that will be a point in favor of getting the device that uses the CR2032.
> 1. how long they will continue to remain rechargable; and if they begin to hold less and less of a charge. if they are still recharging fine for you after 8 years, that seems pretty good.
> 3. how long do they last on a full charge? if use them for camp lights are we going to run out of light after a day ?
The batteries last long enough that I can't answer these questions. I will say I don't own any devices like camp lights where battery life is a significant problem. The batteries in e.g. my Apple Bluetooth Keyboard last for months.
One thing to be aware of is that the voltage curve is different than for alkaline batteries†, so devices like my keyboard will start giving low-battery warnings when they are still mostly charged. This is legitimately annoying on e.g. macOS where you can't disable the warning. Why I would ever want to replace the batteries before they're actually dead is beyond me.
† I don't really know what I'm talking about, this is the explanation I found when I looked up the problem online years ago.
> 2. what happens if the rechargable battery is left inside a forgotten toy or device for 7 years? if I find it 7 years later, is it a leaky mess or still viable? this is a big reason "AA's are disposable anyway, who cares" is appealing - we have forgotten batteries all the time. if we forget about a toy and our $3.50/each batteries are ruined we could be buying a lot of these pricey batteries
I've been using the batteries continuously for that long and they haven't leaked. I'm not even sure these types of batteries can leak? I'd love for someone who knows more about battery chemistry to chime in here.
> 3. how long do they last on a full charge? if use them for camp lights are we going to run out of light after a day ?
The batteries last long enough that I can't answer these questions. I will say I don't own any devices like camp lights where battery life is a significant problem. The batteries in e.g. my Apple Bluetooth Keyboard last for months.
One thing to be aware of is that the voltage curve is different than for alkaline batteries†, so devices like my keyboard will start giving low-battery warnings when they are still mostly charged. This is legitimately annoying on e.g. macOS where you can't disable the warning. Why I would ever want to replace the batteries before they're actually dead is beyond me.
† I don't really know what I'm talking about, this is the explanation I found when I looked up the problem online years ago.
> 2. what happens if the rechargable battery is left inside a forgotten toy or device for 7 years? if I find it 7 years later, is it a leaky mess or still viable? this is a big reason "AA's are disposable anyway, who cares" is appealing - we have forgotten batteries all the time. if we forget about a toy and our $3.50/each batteries are ruined we could be buying a lot of these pricey batteries
I've been using the batteries continuously for that long and they haven't leaked. I'm not even sure these types of batteries can leak? I'd love for someone who knows more about battery chemistry to chime in here.
In my experience, I notice the most leaking problems with devices that constantly draw power, even when off. The battery becomes totally drained then starts to leak.
> 3. how long do they last on a full charge? if use them for camp lights are we going to run out of light after a day
I had some eneloops in flashlights when we lost power for several hours—almost all the batteries died within an hour of use. I will use non-rechargeable batteries for those from now on unless the higher capacity rechargeable ones won’t drain so fast. My kitchen scale, remotes and mice have all been fine (often needing to be recharged only once every year or two) but some uses don’t seem suited to rechargeables.
I had some eneloops in flashlights when we lost power for several hours—almost all the batteries died within an hour of use. I will use non-rechargeable batteries for those from now on unless the higher capacity rechargeable ones won’t drain so fast. My kitchen scale, remotes and mice have all been fine (often needing to be recharged only once every year or two) but some uses don’t seem suited to rechargeables.
For point 2, NiMH cells are _way_ less prone to leakage than alkalines. In fact, I've never seen a leaky NiMH cell (that hadn't completely vented due to severe overcharge, anyway)
1. I've had batteries for 10 years before the charge was small enough I started noticing and began replacing them
2. I've had the odd leak from an unused rechargeable, but we're talking one out of 16 batteries. I've had more leaks with the unused alkaline batteries in the same long-ignored dish.
3. They last as long as their mAh rating. They're fine.
2. I've had the odd leak from an unused rechargeable, but we're talking one out of 16 batteries. I've had more leaks with the unused alkaline batteries in the same long-ignored dish.
3. They last as long as their mAh rating. They're fine.
Enloops low voltage causes a few of my devices to freak out, and my guitar tuner will go into 'boot loops'. Not sure why they even sell them when they don't match the characteristics of the AA form.
I only have them for tv remotes/mice. Alkaline are also reliable for headlamps when I'm in the mountains.
I only have them for tv remotes/mice. Alkaline are also reliable for headlamps when I'm in the mountains.
My reasoning is, AAA or smaller use alkaline, they start off 1.5 volts and last a very long time. (if you use nimh, they are only 1.2V). AA or higher: use nimh or li ion instead, those are generally more power hungry devices.
I think avalanche transceivers need alkaline batteries because they work better in the cold and have a more reliable voltage drop as the energy is drained. But beyond niche applications, rechargeable all the way :).
But lipo AA exist now.
I is rechargeable a for almost everything, but I have some devices which don’t tolerate the lower voltage of NiMH
Why Eneloops instead of rechargeable batteries? Is there an advantage?
Eneloops are rechargeable batteries. They have low self-discharge which means they don't lose their charge quickly like normal NiMH batteries, and can store them charged and devices don't need to be charged frequently. There are now other similar brands but Eneloops are most popular and maybe even generic name.
Just curious are there still "normal" NiMH batteries sold now? It was the normal when eneloop was debut, but I think every NiMH batteries I can find now are switched to eneloop style less self discharging (though some aren't good as eneloop).
I just had the idea to analyze this using scientific methods and write a paper in my spare time (would be my fist paper ;-) ). But seems there is already one: https://www.princeton.edu/news/2015/03/30/battery-bounce-tes...
Quote: "The bounce does not tell you whether the battery is dead or not, it just tells you whether the battery is fresh".
Quote: "The bounce does not tell you whether the battery is dead or not, it just tells you whether the battery is fresh".
Wow. Glad to see that Kipkay is still making videos!
The DIY laser with a DVD burner[0] must be one of the first videos I watched on YouTube.
0: https://m.youtube.com/watch?v=CgJ0EpxjZBU
0: https://m.youtube.com/watch?v=CgJ0EpxjZBU
It really is neat seeing all the different phases his channel has gone through.
I was talking to a founder of a battery company the other day and he said "there are two kinds of moving parts in your iphone, the buttons and the battery". The lithium literally moves from side to side as it charges and discharges.
There is also the speakers, the microphones, the lens (focus), the vibrating motors, and probably a few other things.
The gyroscope and the accelerometer
https://youtu.be/9X4frIQo7x0
Most/all of the capacitors (which are mostly piezoelectric), the inductors, any ferrite beads, and of course thermal expansion. I'd also bet that liquid crystals change pressure when they rotate, but idk.
The glass moves quite a lot once I drop it.
Not so much with modern phones; the glass has gotten a lot stronger over the years. I can drop mine on hardwood with no visible effects and dropping it on concrete only causes cosmetic issues (chipped edges) without affecting functionality. I went caseless and screenprotector-less ~10 years ago and never regretted it.
Well, side-to-side as in less than 100 microns. The inside of the battery is a very long tape that is rolled up like folded paper. The tape is:
1: Aluminum foil (about 1/10th as thick as household foil)
2: Cathode material (metal oxides, like NMC or NCA)
3. Separator film (polypropylene + polyethylene, which blocks electrical short circuits but lets li ions through- only ~20 microns thick)
4. Spheroidal graphite anode (mostly artificial, some natural)
5. Copper foil
The ions (and some amount of solvent- the solvation sheath!) travel from cathode <-> anode.
1: Aluminum foil (about 1/10th as thick as household foil)
2: Cathode material (metal oxides, like NMC or NCA)
3. Separator film (polypropylene + polyethylene, which blocks electrical short circuits but lets li ions through- only ~20 microns thick)
4. Spheroidal graphite anode (mostly artificial, some natural)
5. Copper foil
The ions (and some amount of solvent- the solvation sheath!) travel from cathode <-> anode.
So, can we, in theory (I guess the effect will be small), measure battery charge by measuring the center of gravity and/or rotational inertia of batteries or even smartphones?
No- the inside of a li-ion battery looks like this: https://www.researchgate.net/profile/Jigang-Zhou/publication...
Li-ion battery comes off the production line as one continuous, miles-long tape that is rolled into shape and then sliced off. The tape is made of a few layers, and li ions move from one layer to another. All of the movement cancels out.
You could measure the state of charge by mass, though! As electrons are moved from anode to cathode, they occupy a lower energy state and therefore have less mass. You'd measure that in eV, electron-volts: convert amp-hours to coulombs and you have the number of electrons, and the average voltage change is from roughly 3.7 volts to 3.2 volts. Or you could use the much easier formula- E=MC^2 :D
Li-ion battery comes off the production line as one continuous, miles-long tape that is rolled into shape and then sliced off. The tape is made of a few layers, and li ions move from one layer to another. All of the movement cancels out.
You could measure the state of charge by mass, though! As electrons are moved from anode to cathode, they occupy a lower energy state and therefore have less mass. You'd measure that in eV, electron-volts: convert amp-hours to coulombs and you have the number of electrons, and the average voltage change is from roughly 3.7 volts to 3.2 volts. Or you could use the much easier formula- E=MC^2 :D
> All of the movement cancels out.
For the center of mass, that’s right, but that will change the moment of rotational inertia, won’t it? Mass will either move inwards or outwards as the battery gets discharged.
For the center of mass, that’s right, but that will change the moment of rotational inertia, won’t it? Mass will either move inwards or outwards as the battery gets discharged.
Well, for the outside layer only, since the inside layers are effectively just shifting slightly.
The battery as a whole swells slightly due to the stress of intercalation, which is certainly a much larger effect.
The battery as a whole swells slightly due to the stress of intercalation, which is certainly a much larger effect.
This might be the first YouTube video I’ve ever actually upvoted. No bullshit, no filler, under 1 minute with all the information shared. Bravo.
Maybe the content is ok, but the voice sounds like it was produced with a swap-meet bullshit generator. I think I'll stick to my multimeter.
There's a lot of discussion in the comments here about the format, but it's ironic because the title of the submission tells you everything already in <5 seconds depending on how fast you can read / interpret.
It's a quite known fact for long time. Still testing the voltage w/ probes (and under load) is the way to go.
Here's the paper abstract; full text behind paywall: https://pubs.rsc.org/en/content/articlelanding/2015/ta/c5ta0...
Thanks to youtube, we are satisfied enough. These people are asking for $50 for the article. Weird.
Welcome to the biggest scam in science. Research funded by the taxpayer, peer reviewed for free by other scientists in a journal run by volunteer editors all to be hosted as a PDF for massive profit by a ‘prestigious’ journal.
Oh don't forget, the journals charge a fee to submit as well. I believe a number have "open access" submission fees much higher than normal submission.
Most (at least in my field, can't say about others) don't really charge, but yeah some do. And about open access -- some journals force you to choose open access (and hence more expensive) too.
Can't believe it's still an issue in 2023. The number of times I've gotten to a paywall for an mildly interesting article and I've just walked away because either the institutional access is broken, or not covered or there's simply no way to work out where the full article is.
It's sad that people who have forgone higher financial reward and pursued a life of exploration and discovery are prevented from discussing their work unless the rent-seeking middleman gets paid.
At this point, other than being the arbiters of prestige, what do the journals offer that direct peer review does not?
At this point, other than being the arbiters of prestige, what do the journals offer that direct peer review does not?
What is the scum part here?
Well the archival and distribution costs (the only part they really do) don't seem like they should cost $50 for say a PDF file in the 10s of MBs.
I think the fair value of what Elsevier (say) provide is > $0, but it's interesting to compare with say Spotify or Netflix - who actually have to pay for content.
I think the fair value of what Elsevier (say) provide is > $0, but it's interesting to compare with say Spotify or Netflix - who actually have to pay for content.
Don't forget most journals take a publication fee in the hundreds. And pay per reviewers nothing.
Yep, I guess the reality is that they make all their money from "enterprise-like" sales to educational institutions.
Speculating: the reason they slap a $50 charge "per paper" for non affiliated access is that they don't actually care about those sales, that's not where their revenue comes from. Essentially that is the "sucker price".
Speculating: the reason they slap a $50 charge "per paper" for non affiliated access is that they don't actually care about those sales, that's not where their revenue comes from. Essentially that is the "sucker price".
Paying for something to access that tax payers already paid for in the first place ? How is this rocket science.
Just like float-testing my eggs
It’s true a properly charged egg won’t bounce!
Just what I was thinking of. Putting it on a surface and spinning it also works, a raw egg will stop fast due to sloshing, a hard-boiled egg will spin for a while.
The float test is for freshness. I use it a lot. But never saw a floating egg, also never had a bad one. Time for an experiment I guess.
> also never had a bad one
Consider yourself lucky. I had one, breaking them into the bowl for the scrambled eggs and one of the batch was foul. I was ~8 at that time and if my parents weren't there I would probably just run away never to get back to that kitchen, house, city.
Consider yourself lucky. I had one, breaking them into the bowl for the scrambled eggs and one of the batch was foul. I was ~8 at that time and if my parents weren't there I would probably just run away never to get back to that kitchen, house, city.
You can also quickly stop the raw egg, and it'll start turning again (unlike the hard-boiled one).
> isNaN(egg)
false
I kind of love how the TikTok version would just show the battery dropping and a caption, and then you could move on with your life
funny how this "30 second" 44 second one was supposed to be quick and engaging
funny how this "30 second" 44 second one was supposed to be quick and engaging
And both would be forgotten by the time the next video would start.
Still, Vine was the epitome of 'to the deal'.
Still, Vine was the epitome of 'to the deal'.
Anybody else lick their batteries?
can you tell 1.5v? I do check 9v battery by tongue.
Same exact concept of course, just pointing out that you don't have to actually watch it bounce and fall over, you can hear it pretty easily. Helpful when testing a drawer full of suspect batteries...