Rechargeable Batteries: Pros and Cons

source was at the end. Okay, after we've finished recording. Doesn't really give much of a challenge if I tell everybody what it came from. Uh, so we're gonna You

might remember that from several episodes ago we talked about batteries. Yeah, yeah, and it's it's funny because, um what, what the listeners don't know is that beforehand, when we started comparing, uh just doing a quick comparison notes on what we were going to talk about, we realized that it was probable that we were going to go over and as it turns out, we had plenty for that and more left over.

So here we are on batteries Part two. Mainly we're going to talk about rechargeable batteries and the issues around recharging batteries and some of the some of the other stories that are related to that, for example, batteries exploding. Yes, we'll get into that. So rechargeable batteries are a special kind of battery. Not all batteries are rechargeable. Well, that's true, and it isn't. That's the that's the funny thing about

about the batteries. When I was doing some research on exploding batteries, um, I was reading about the thing that you're not supposed to do with alkaline batteries, which is to put them in a battery charger. The thing is about alkaline batteries. They can be recharged, but they're not designed to be and putting them in a charger will cause the cause them to start charging, and it will cause them to explode because they're not that's not the

way they work. But it can happen. I mean, it's not the The rechargeable batteries, the ones that are marketed is rechargeable, are designed to be rechargeable, and therefore you can put them in a rechargeable right, So in case you don't remember. The way a battery works is that there's a chemical reaction that generates electrons. The electrons travel through a circuit and then back to the battery because because there's a negative terminal and a positive terminal. Negative

terminals where the electrons are coming through. Positive terminal is where the electrons are attracted to and re enter the battery. And eventually you use up all the chemicals that are inside the battery and it becomes inert it's used up and dead. Yes, in a regular battery, that's the way it works. Now with rechargeable batteries, what you do is you reverse the flow of electrons. You create a more powerful flow of electrons that will go back the way

the electrons usually come. So you're reversing the entire process, and through that reversal, you begin to reverse the chemical reactions that took place inside the battery and it goes back to its pre discharged state. Yes, well, that took took way less time than I thought it would. Um so ever, lunch, Well, that's a um a simplification of the process. Of course, it all depends on the type

of battery. There are many different types of chargeable batteries, some of the most popular being lead acid, UH, nickel metal hydride nickel m I on. But you mentioned lead acid before we go a bunch further, I did want to mention that is technically the first rechargeable battery, is it. It was discovered in eighteen fifty nine. There was a French physicist, Gaston Plant and Gaston he was as smart fellow and um, yes, he didn't discover it. He opened the door one day and said, what is this thing?

Someone just left this thing laying or hey, that's a lead acid battery. He actually discovered the whole process of you know, using created a lead acid battery and discovered that by reversing the flow of all atron's by forcing electrons back through, you would essentially reverse the chemical reaction. UM. Lead acid batteries, of course are very important. They're used and almost well, they're used in all gas powered vehicles, right.

That's the that's the battery that your gas powered vehicle uses to draw power for things like the headlights and the radio as well as other stuff. And the interesting thing about the lead acid battery in your car is that your car actually recharges the lead acid battery. That's the way it's supposed to work. Yeah, not always right, in a properly working vehicle, your car is recharging the lead acid battery, and I conclude the batteries part of

the vehicle in that case. Yeah, what happens is you have a there's a device inside your engine called the alternator inside inside lots of engines. I had my very first car had a generator in it, just slightly an alternator, right, And and also if your alternator goes out, that's awful. Yes, as my wife discovered on one evening, Yeah, that was not good. That's a highway in in the Atlanta area,

better known as the Perimeter. The Perimeter is also known as the Raceway in the Atlanta area where if you're not going eighty five miles you better be dead. So anyway, the alternator recharges the battery as you drive. So that's why your car battery will last a pretty long time. Now, typically, if you were to use a lead acid battery and you weren't recharging it, it would not last that long, Like the energy would give out much more quickly than

it usually does. But it is getting constantly little amounts of recharge every time you're driving it, so um. Uh. That's again, that was the first rechargeable battery that was discovered to be you know that it was the first time anyone discovered that you could reverse that chemical reaction. Um. Since then, of course, we have discovered that other materials also work really well in this uh this format, including the nickel cadmium and the lithium ion and batteries like that. Yeah.

They're one of the things that's interesting about rechargeable batteries is that different rechargeable battery types are useful for different applications. Um. That's why you'll still see lead acid batteries used in cars, and you still see uh, nickel cadmium and nickel metal hydride batteries used in all kinds of things that you put double a, triple a, nine volts, etcetera. Uh in

a little portable devices usually right right. And you see lithium ion batteries in electronics such as computers and portable music players and the like. The different the different properties of the batteries themselves make them appropriate to use in those different uh, different applications, right, Because depending on the materials you're using for your battery, that's what's going to determine the the actual voltage and current that's going to

come from that battery. So you know, some materials are not going to be useful for certain applications because it's going to require more electricity than that battery can generate unless you were to make an enormous series of batteries, and at that point you're you're sacrificing so much in terms of weight in order to get electricity that it's wasteful. That was one of the big complaints that I remember

and the nineties about the idea of electric cars. They were using lead acid batteries and as most people know, lead is extremely heavy. Um, you know, a pound of lead being equal to the weight of a pound of feathers. But nonetheless, you just blew my mind. Yeah, none. Nonetheless is anyone who has changed their car battery knows, um, other than to wear gloves while you're doing it and avoid charging it when you don't have any eye protection

on and you're standing right over it. Um. They are extremely heavy because of of the lad inside, and that made a lot of the electric cars in the rather impractical because just the sheer weight of the amount of batteries needed to power a vehicle was made. It just really um, not practical at all. Yeah. UM. It wasn't until we discovered other materials that had better energy density than uh than the lead acid that that electric cars started to become h less of a of an obstacle

that they used to be. Uh. Lithium ion certainly excels at that, right. Lithium ion has a very strong energy density. UM. It can generate quite a bit of electricity. And so you know, your relative to the size of another battery made out of a different material, lithium ion is uh is generates more energy essentially or more electricity, I guess I should say specifically. Now we were about to talk

also about the exploding batteries. I think this kind of leads into it because people may have heard about lithium ion on batteries and having overheating issues and um, even batteries that have burst into flames or or exploded. However, you want to determine that, um. First of all, a lot of different batteries have the potential to burst into flame or explode because some of the materials inside lots of batteries happens to be flammable. I think it's safe to say it's a it's a good idea to treat

the contents of batteries as hazardous. Some of them are caustic, some of them are are non toxic. But unless you happen to be intimately familiar with what's inside the can, it's better to treat it as something that will harm your skin. Uh is something you don't want to get in your eyes or nose or mouth. Um, you know, handle with care gloves and perhaps a pair of safety goggles, and you don't know exactly what it is that you're dealing and you don't want to be puncturing these things

or anything like that. Don't throw batteries in the fire, right, Yeah, they there are chemicals in there that could be dangerous under different circumstances. Now, with lithium ion, that happens to be lithium, which is quite flammable as it turns out, And um, it's not just that the lithium is flammable. There are a couple of elements at play. One is that I didn't mean it that way, but anyway. One

of them is that Uh. In the manufacturing process of creating a lithium ion battery, one of the byproducts within the battery are these tiny little metal particles. And depending upon how exacting the procedure is for the manufacturing process. So this really depends on the manufacturer, you know, how how careful they are, you may have more or fewer

of those metal particles. A fewer would be better. UM, because what happens is as you charge the battery, or even as you use it, it starts to generate heat. It's one of the by products of this whole process. It's not just the chemical reaction. Doesn't just generate electricity, also generates heat. UM. As that heat is generated, the metal metal particles start to move around inside the lithium ion batteries. Well there's um. There's a separator inside the

lithium ion batteries. If you remember in our previous batteries podcast, we talked about the anode and the cathode, and you have to have a separator between the two or else the electrons will just travel directly between the two instead of going through the circuit that you've plugged the battery into. So these little metal particles can sometimes puncture that separator and that creates a short circuit. So now the electrons can flow freely inside the battery instead of going through

the circuitry like it's supposed to. And this will cause batteries to heat up much more quickly because you know, you've just you just removed that that pathway, and the electrons will move very quickly speed of light essentially UM, and the battery will heat up. And if the contents of that battery are flammable, as is the case with lithium ion batteries, the battery could burst into flame, which is spectacular and dangerous and very scary and can set

your pants on fire. Yes, I actually have an article about that's setting your pants on fire. Sorry, go ahead, we do. Indeed, UM that that was essentially what I was I was going to get to was the fact that a few years ago it UM UH, this thermal runaway as it's known UM, was a big item in the news. They had discovered Uh. Sony and Apple both got blamed for batteries a few lithium ion batteries that

had UM overheated and caught fire. UM. As it turned out, they came from another you know, like most computer components, they came from another manufacturer. UM. And UH, of course I think there was the whole iPod setting your pants on fire thing, which, as Jonathan mentioned, there is an

article on our side about it. UM. But as it turns out, they're not these things obviously there there may have been in a lot like that, uh, defects in the manufacturing process, but in general, UM, it's very unlikely that it's going to happen. So uh, you know, I have also heard that it's possible to drop a lithium ion battery and it can cause it to UM can

cause problems like that too. I would imagine it's probably the same thing if you drop it from you know, the lithium iron batteries are using a lot of power tools because it happens. I used to work for a company that sold power tools, and they said, don't drop your lithium ion batteries those toys r us right no, and uh so, although they do sell lots of lithium ion batteries, because I believe I can't remember if lithium

ion or or nick um not nickel metal hydride. The lead acid are the ones that they use in the kids vehicles. I think they're lead acid that they use for wheelchairs, and that I think that's in my notes somewhere, but I'll have to stop talking and let you oh, well, that never happens. For you guys out there who were curious about the the iPod story we have and the article that we have. The article title, just so you know, is how can an iPod set your pants on fire? Literally?

And it was written by Josh Dreamy Eyes Clark of stuff you should know. Um, so you should check that out. And uh, it's a good article, really good article. So yeah, there's another way that these batteries can suffer damage is through overcharging. I know we had a podcast earlier, way way way back in the day where we talked about is it possible overcharge your devices? Uh, technically the answer

to that is yes, it is possible. But most recharging cables and and systems have a safety measure in place that will shut off the recharging once the battery has reached capacity. They they have they are able to measure the the energy density of the battery that is currently being charged, and once it reaches its full level, the the recharging, Uh, the the electrons pathway to the electrons are just essentially cut off. So you're not going to

overcharge your your battery using the right cable. Me. If you're using a really cheap cable or your Jerry Riggs something so that you can try to recharge your batteries, then I can't you know, vouch for that. You could theoretically overcharge your battery and cause damage and possibly that could lead to an explosion or fire. Uh. I was also going to mention, UM, did you find the thing

you were looking for? Yes, Lead acid batteries are used in in wheelchairs and cars and kids toys, so stuff like the UM you know, the little cars that they use where you get in has the motor UM. Pretty nifty things until you get your toes run over a few times. I'll take your word for that. I mean I don't have one of myself. I don't fit in them anymore. I, you know, am pleading that I know nothing about that. Okay, So there was something else I

wanted to talk about rechargeable batteries, which was the memory effect. Yes, but that's not pertinent to all different types of the chargeable batteries. Really, Nickel cadmium is the one that is typically to blame for the memory effect, and I can explain that if you want, please do. UM, I found a whole series of articles um by somebody that I really liked, and I'm now trying to scroll down until

I get to uh the name, get to his notes. Um. But the chemical makeup of the battery is has a lot to do with the memory effect UMA for me, Okay, I'll let me explain what the memory effect actually, that's good. So the memory effect is when if you let's say, let's say you've got a battery and you've you've used up about half the charge of the battery, and then you recharge it, and you use up about half the charge of the battery, and then you recharge it. You

do this a few times. Certain batteries, the nickel cadmium batteries in particular, will eventually retain memory wory of that you used and think that's the full of the batteries charge. So in other words, you will never be able to get a percent performance out of that battery. What will happen is it'll discharge to and then the battery, uh

will stop working because of the memory effect. It it doesn't literally think, but it quote unquote thinks that it has uh it is has discharged its full charge even though it remains untouched. Now you're going to say, has found a whole series of articles by uh, someone from CADEX Electronics. His name was Isador Buckman, and um wrote a whole series of really interesting articles about about batteries.

He's very apparently knowledgeable about batteries. Um. But there's the nickel based batteries have something that Buckman calls rock content, and that's and that's the memory, that's the memory effect basically. UM. The idea is that you have to go for a complete cycle, which is what we were talking about a long time ago in our Charging Batteries podcast before, where you let it run all the way out and then you know, plug it in and land it charge all the way back up to give it a full complete

cycle of charge. Um. But but the thing is, UM, the the oxidate or the chemical reactions basically UH make part of the battery unusable. And that's why you have to go through the deep cycle process to do that. Now, the other types don't have that same problem. And in fact, lithium ion you're I I remember being told never to do a full discharge of lithium ion battery because that will make it um useless. You can't recharge it once

it's been fully discharged. Yeah. Um. Marshall Brain's article on how lithium ion batteries work on the site to us that UM, and what happens in that case, according to Buckman, is that the oxidation just by use and aging the a lithium ion battery will gradually just become unusable just because the the guts of it, if you will, are are going through the oxidation process. UM. Buckman says there's about two or three years UH for doing that and

whether or not you're using it. If you charge up your batteries to be used in your emergency emergency flashlight, you put the flashlight in a drawer. Um, two years go by and there's suddenly an electrical storm and you lose power, you reach for that flashlight, you may not have any battery left. Yeah, you still have to replace it regularly. UM. You know, you can keep it at at at charge in a in a cool place to help prevent that, but you're not going to prevent it

no matter what. And there's also no memory effect with with UH with lithium I and you don't really need to condition them, which is which does con predict what we said in that podcast because I remember specifically saying that, so, uh bad on me for not finding Mr Buckman's article before. Then. Well that was the thing is that it's confusing, right,

because it all depends on the type of battery. With the nickel camium, you have to you don't have to, but if you want to avoid the memory effect, you need to discharge it as fully as possible before you start recharging it, because otherwise the little crystals that will form in that battery will well coagulate and get bigger, and the crystals will get bigger. And as those those crystals essentially you can think of it as they take up space and become inert. So the more crystals formed,

the less power your battery is going to have. So if you discharge it all the way, those little crystals don't really form as quickly, they don't coagulate or whatever, then you can recharge it and you're fine. Um, if you just discharge it a little bit, then those crystals get bigger and bigger until that part of the battery gets unusable. So yeah, in that case, you do need to use it all the way down and then recharge it all the way back up. Uh. Lithium ion is

not that way. In fact, some places I've seen so that there's uh, the best way to keep your lithium ion battery lasting a really long time is to keep it charged between forty and and you don't charge it over sixty, and you don't let it drop below forty and it will last. That'll that'll let the battery last the longest over the lifetime of the battery, not I'm

not talking about you know, playtime or whatever. If you hook up a lithium ion battery and it's charged at six you're not going to get you know, ten hours of use out of it like you would with a full fully charged battery. But over the course of the lifetime of the battery, you'll get more years of use out of it. So that's a little too much battery

management for me. I can't do that. I can't. I'm not going to be you know, sitting over my devices watching that that little number creep up and then say, oh, it's at six percent, I need to unplug it. You know, it's not really realistic. But the other yeah, the consequence of that is that I do this knowing that the battery is probably not gonna last as long as it would if I did take that trouble. Yeah, it's too

much trouble for me. Well, it's funny because, um, a lot of the batteries, a lot of rechargeable batteries, um, have a very long lifespan if you manage them. Well, um, but the properties of each are different, like for example, uh, lead acid batteries need exercise. They really actually need to be used a little bit, um frequently, you know, just a little bit at a time to keep them healthy

essentially and keep them from from running out on their own. Yeah, if you if you left a car alone long enough, you may discover that, uh, you know, the battery might have been fine when you left the car, but now when you finally returned to it, the cars not starting up properly. That could be because the battery itself, you know, has been left unattended for too long. It also can happen in very cold weather because that slows down the

chemical reactions. Right. Yeah, going through the my notes, and there's just I've got a lot on on how batteries should be charged. Um. That that's something else interesting too. Uh. You know, I've I've seen the chargers that have the like the fast charge cycle advertised. You don't do that with elithium ion battery. It's very bad for a lithium ion battery to try to make any attempt to uh

to dump a charge into it. And really the fast charge cycle um like you see for some of these devices, it's not really meant to be the regular way you charge the battery. It's supposed to be sort of an emergency situation type thing. It's not that can actually be

harmful to a batteries lifespan if done frequently enough. Yeah, there's certain certain kinds of batteries where the chemical balance in there is the sort that can accept a very large, uh short burst of voltage with out they're being too much damage to the battery itself. But not all batteries are created equal in that. So that's a good point.

And of course you should always pay attention if you ever hear a story about a battery recall, definitely pay attention to make sure that you know none of the devices you have are are covered under that because this is serious stuff. If they discover that there is a fundamental flaw in the manufacturing process that could lead to a fire, you definitely want to pay attention to that. I mean, I know a lot of people who leave

let's say, like their their computer on all day. You know, they might have a laptop at home and they'll just leave the computer on all day rather than turn it off and turn it back on and they get back. Um, if that battery has a fundamental flaw in it, then that could become a source of you know, a fire. You come back home and there's nothing there. Yeah. I think a lot of people might be surprised, depending on how long they've owned a computer. Even desktop computers have

a battery in them, that's true. Um usually anyway, I can't think of one that doesn't. My even my Amiga from back in Can we get through one episode without you and talking about that Amiga? No? So um no, there but there is a battery and there basically so

if you shut it down and maintains the clock, right. Yeah, that's why when you plug your computer in after or if the power has gone out or whatever, and you look at the clock and it's still set at the correct time, or at least the time it was keeping before the power went off, that's why. Um, let's see, is there anything else specifically that covers everything that I had. I was really I was just determined to talk about pants getting set on fire. UM. But yeah, if you

are one other thing that I thought of, just a tidbit. Um, if you have a device that you know is going to be sitting for some time, or like a kid's toy that runs on batteries that you're putting away, it's a good idea to take the batteries out of it. Um. We talked about the um corrosive nature or of the chemicals inside batteries. I went to an energizer actually has

an interesting bit on their website about cleaning up. Basically, they say that the contents of their alkaline batteries are actually they're they're they're fairly non toxic, really, and they don't have to be recycled, although I do recommend doing that, and I think they would too. UM, but they're they're not. There's nothing terrible that would leach out of them, as would be most of the chemicals and rechargeable batteries. However, if left too long, these the chemicals inside can't start

leaking out. And even if you don't aren't necessarily concerned about the device, UM, it can cause like if you're going to donate it to somebody. So you found these old toys and you want to give them, do you know charity and say, oh no, go ahead and take them. Those leaking chemicals can damage the device and can cause problems from other people. So if you do encounter a a leaking battery, you know, please be very careful with it,

handle it with gloves. Probably a good idea to use safety glasses and put it in a leakproof container when you're done. Now, speaking as someone who has been burned by battery acid, I second that recommendation. In car batteries, you know that there and there's some seriously dangerous chemicals and there's acid in there um that can burn you very badly, and and car batteries should be handled very very carefully if you try to recharge them yourselves, I

think you just let car stuff handle that. They can also generate hydrogen, which is extremely flammable. So you get an electric spark or a flame anywhere near a battery that happens to have some hydrogen built up around it, and that is seriously badness. I'm sure you've all seen video of hydrogen explosions and it is dramatic and scary. You don't want to have that happen. Yes, that's true. Yeah, that's actually Um, even with trying to plug an alkaline

battery and a charger. Um, that's what goes on, is not I don't know if it's hydrogen gas. That will admit to not knowing that. But uh, the recharging process in those batteries starts a build up of gases inside the canister that the battery is in, and that's what causes it to explode if you try to recharge a non rechargeable battery. So that's what It's very dangerous to do that and nobody really wants to have that problem. Yeah, so don't do it. All right. Well, that pretty much

wraps up this discussion on rechargeable batteries. I got a big charge out of it myself. Did you find it shocking? Not really? I found a revolting really do you guys? Stay current with the sourt of stuff. Guys, if you have any questions or comments or you have topic suggestions, you can let us know on Twitter and Facebook are handled. There is text stuff h s W or you can send us an email and that email address is tech stuff at how stuff works dot com and Chris and

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