A simple way to test the charge level on alkaline batteries (2015) [video]
youtube.com
youtube.com
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...
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.
But if you want to separate 1.4 volt batteries from 1.5 volt batteries, use a multimeter.
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.
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 :)
"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)
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".
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?
…Too soon?
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 believe your trick works for a different reason - zinc-air batteries get heavier as they discharge since they absorb water from the air.
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.
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 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.
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 ?
> 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.
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.
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.
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.
I need to ask, do you work with these things daily, or do you just have an exceptional memory?
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.
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.
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.
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...
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
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.
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.
I only have them for tv remotes/mice. Alkaline are also reliable for headlamps when I'm in the mountains.
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.
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.
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?
Quote: "The bounce does not tell you whether the battery is dead or not, it just tells you whether the battery is fresh".
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
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.
The battery as a whole swells slightly due to the stress of intercalation, which is certainly a much larger effect.
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.
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.
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".
At this point, other than being the arbiters of prestige, what do the journals offer that direct peer review does not?
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.
> isNaN(egg)
false
funny how this "30 second" 44 second one was supposed to be quick and engaging
Still, Vine was the epitome of 'to the deal'.