Boiling Batteries
Mark Honeychurch - 12th December 2022
I have a friend who I’ve written about before who, although she’s always had pseudoscientific ideas (like giving her children homeopathic remedies), since the pandemic has fallen down the rabbit hole and is currently at the bottom of said hole, picking up more and more daft ideas as she sits there, wallowing. I haven’t seen her in a while now - not since I bumped into her at the parliament protest in February - but I do hear about her recent high jinks, and I see her Facebook posts which suggest that she’s given up any effort to think critically.
A couple of weeks ago, she shared a video titled “Battery factories don’t want you to know this!”, which you can watch at:
The “trick” that Big Battery doesn’t want you to know is, apparently, that non-rechargeable batteries are actually rechargeable. Presumably the battery lobby keeps this quiet to maximise their profits - after all, if we were all able to recharge our batteries, we’d never need to buy new ones.
So, what is this one simple trick that has been suppressed and hidden from us? Easy, just bring a pan of water to the boil, and drop your batteries in there! Here’s how the voiceover for the video starts:
I have never bought batteries again since I learned this hack. Our grandparents used this trick. So, guys, check this out.
You probably have a lot of discharged batteries like these at home, right? I have all these in my house, and these batteries can cost a lot of money. Especially this brand right here (holding a Duracell battery) - a small package of them, at least here in my city, can be quite expensive. So, here’s the thing.
An old friend gave me this tip on how we can recharge this type of battery, even though they’re not rechargeable. I tried it here at home and, to my surprise, it really worked.
The narrator then proceeds to show that the batteries are discharged, by putting them into a set of electronic weighing scales and unsuccessfully attempting to turn the appliance on. He continues:
So this is what we’re going to do. First, put some water on to boil. Then, take the discharged batteries and put them directly in the water. Let’s leave it here for about 1 minute.
…
After the time, we can turn off the heat. Let’s go ahead and remove the batteries now. You’ll see that the plastic shrinks a little, but that’s totally fine because of the hot water. So go ahead and remove the batteries, but be sure to leave a container with very cold water right next to it, alright, so we can give them a thermal shock to bring them back to life. And to help even more, add some ice cubes too. Let’s leave it here for two more minutes.
He then removes the batteries from the cold water, using a paper towel to dry them. He places the batteries into the scales, and the scales now turn on. He finishes by saying:
It’s a really good life hack to save money. So, if you have bad batteries there, don’t throw them away any more. Try this instead, and you’ll definitely be able to use them for much longer.
Okay, so in case this needs saying, I’m going to state this now: Don’t boil your batteries in water. Not lithium batteries, or alkaline ones, carbon zinc or silver oxide. And the same goes for rechargeable batteries - nickel metal hydride, nickel cadmium, lithium ion, etc. Just don’t do it. Why, because it’s dangerous. Batteries contain acid, and this can leak. They can also explode. Additionally, you can render rechargeable batteries useless if you heat them up.
So, assuming this trick actually works, what might be going on here?
Well, batteries work using a simple chemical reaction where an acid electrolyte reacts with two different cathode and anode metals, and the reactions with both metals result in a flow of electrons between them. Once reacted, the chemical products drop to a lower, more stable energy level. When most of the chemicals have reacted and produced their electron flow, the battery is considered dead. With rechargeable batteries, pushing electrons back through the battery’s circuit can reverse the chemical reaction, placing the battery back into a high energy state where it can then be reused. Modern batteries are mostly “dry cell”, where a paste (possibly ammonium chloride) is used as the acid, and the cathode and anode might be carbon and zinc respectively.
Of course, when a battery is considered “dead”, it’s not actually stopped working - it’s just come to the point where the remaining reaction doesn’t produce enough voltage to power the device the batteries are plugged into. But it turns out there are some ways you can coax a dead battery to increase its reaction rate for a little while, ways to nudge what little reactants are left to come into contact with each other and give a final little burst of energy. Throwing your batteries into boiling water is likely to be one of those ways that you could have an effect on the internals of a battery, to cause the chemicals inside to shift a little and provide a slightly more vigorous reaction for a little while.
There are other “old wive’s tales” of how to revive batteries, to get them to start working again. Banging them against a table or other hard surface is one of them, as is throwing them on the ground. And freezing them is another one. All of these seem to share this same method, that you’re trying to nudge the internals of the battery just enough to get a little more of the chemical reaction to happen. (Again, I shouldn’t have to say this, but in case this article is being read by someone on the internet looking for a way to save money, do not drop, throw, bang or freeze your batteries!)
So, it seems that this “one simple trick” isn’t actually recharging the batteries at all, it’s just letting you squeeze a little more power out of them. And that will probably only give you a very small amount of extra battery life. This may look impressive for a device like a TV remote control, where the device is only used for short periods of milliseconds or seconds, and draws a very low current - you might get an extra week or two out of batteries that have already lasted for two or three years. But for a device that needs to be powered continuously, like a digital camera, you’ll probably find that this extra oomph only gives you another minute or less of usable power, if anything.
This difference in device power requirements probably explains why the video I watched chose to use kitchen scales as their testing device - it would have looked a lot less impressive if the batteries had been placed in a high power draw device like a torch (flashlight if you’re so inclined), and the light level started dropping as soon as it was turned on. Of course, after explaining all of this to my 15 year old daughter, she pointed out that the video was also not a continuous shot, and any of the cuts could have been a good opportunity to swap the dead batteries out for fresh ones. (And yes, I’m definitely a proud father whenever one of my daughters comes up with a skeptical point like this)
This silly idea reminds me of another, older internet hoax that spread through viral videos - the idea that larger batteries, from square lantern batteries up to car batteries, are made of lots of smaller AA or AAA batteries. These hoax videos would show someone cutting into a car battery, for example, with a hacksaw, peeling off the top, and then pouring out a hundred or more AA batteries.
The truth is that some of these larger batteries, like the lantern battery, will likely contain smaller sealed battery cells, but those will not be AA sized, and there won’t be 32 of them. You’re likely to find four large 1.5v cells soldered together with wires in a 6v lantern battery - not something that’s usable in your home appliances. And again, for any random people on the internet reading this article, DO NOT CUT INTO A BATTERY WITH A HACKSAW.
Thankfully it appears these videos have been expunged from YouTube, and replaced with more sensible videos where people debunk the rumours:
So, if these tricks don’t work, how do you extend the life of your AA batteries at home? Simple, use modern rechargeable batteries. But bear in mind that they’re not cheap, and they’ll usually run out of power quicker than a good quality disposable battery - so they won’t be appropriate in all cases. However for some cases, like kids’ toys that need a lot of power and are used sporadically, you might find that rechargeable batteries hit that sweet spot where they’ll end up saving you money.