Inside an emergency urine, sea water or salt water powered light

Added: 2026-06-05

[00:00:00]Let's take a look at an interesting emergency light powered by urine. It in reality is powered by salt water, but you can also use seawater or in a pinch you can use urine if that's all you've got handy. So, let's cut straight to the chase here.

[00:00:14]This unit um you add salt to it and it says it comes with two sachets of salt, but it doesn't. It does say that in the listing as well, but it doesn't come with the salt. I wonder why they're not shipping that. Is it because it falls into category of drugs or something?

[00:00:28]But you open it up like a ziplock bag and there's a little electrode you can see down there and you add 10 g of salt.

[00:00:34]Here is 10 g of salt. Let's bang that in.

[00:00:37]And you top it up to the water level line here with water.

[00:00:44]I shall do that right now. Not sure how much water it takes, but I'll tell you that in a moment because once I've topped up, I will wait cuz I weighed it beforehand and we'll see roughly what difference there is.

[00:00:57]So, now you close it again.

[00:00:59]Making sure it is properly closed cuz now I'm going to shake it. It's too low focus at the top, isn't it? That's fine.

[00:01:05]Note that there's a breather vent here.

[00:01:06]They say you shouldn't leave it upside down. It has to stand like that when it's in use.

[00:01:11]Uh but I'll shake it and we'll also let the unit sit for a while because it takes a while for it to soak into the electrode area. But then we can open this up and we'll strip everything apart once we've tried it out.

[00:01:24]So, I have given it a good thorough shake, let it sit for a while and it should be up to power now and it's not mega bright.

[00:01:34]It's got two modes. You click it once, it lights. You click it the second time it does its SOS thing.

[00:01:41]Except that's not really SOS, is it?

[00:01:48]That's uh very odd. But anyway, it does its little strobing thing.

[00:01:52]Uh let me turn the lighting off and show you what this looks like.

[00:01:56]And I will say, yeah, it looks impressive, but the camera is flattering it. However, having said that, I could read by this and it would be a comforting source of light. Let's just sit it like this and point it over there. Yeah, that's all right. I mean, yeah, the camera is doing it favors. Let me try and adjust the intensity to show you what it really looks like.

[00:02:17]Yeah, I'd say that's closer a closer emulation of what I'm seeing here. Not mega bright, is it? But still actually quite useful for doing basic stuff. And as I say, nice as a source of comfort light. Okay, watch your eyes. It's about to get bright again.

[00:02:34]So, now you've seen it lit, we can take apart. So, the thing about this is they do claim that it can be filled with sea water or urine or just water.

[00:02:45]Um, but the light is brighter when salt is added cuz it is basically it A lot of the sellers try to imply that it's the water that's generating the power. The water is just an electrolyte. What's generating the power in here is the metals of the electrodes.

[00:03:01]But it also says, period of illumination at least 140 hours of continuous use, probably reduced intensity, not sure.

[00:03:09]And up to 200 hours of intermittent use.

[00:03:10]Can be used for up to 70 days with water and salt inside or if you put it in the storage, you can pour the water out, rinse it, uh, and then dry it out, just leave it open to the air. And uh, store it for a long period of time. That is the main benefit of this is that it is stored dry, so there's no electrolyte to leak or degrade. Okay.

[00:03:31]Right. Well, I'm going to empty this out, then we can open it. One moment, please.

[00:03:38]Okay, let's get moist, shall we? I do have paper towel on standby. Let's cut our way into this and get this module out and see what it looks like.

[00:03:52]So, the first thing seeing here is a very very big electrode with some sort of sealant. Oh, that's to stop electrolytic corrosion with the screw here.

[00:04:03]But, that is probably one of the electrodes. And then there's a gap, and then there's what looks like another electrode in here. But, what's this mesh for? I suppose there's one way to find out, and that is to open up further.

[00:04:13]But, that might be quite destructive cuz it looks as though it may be kind of welded together. Okay, one moment, please.

[00:04:20]Okay, I shall zoom in, and it's time to get crunchy. First thing I've done is unscrew the screw. It's covered with silicone, not just for the prevention of the corrosion of the interaction of the two metals, but also because it's to stop water going through here and penetrating into the unit here.

[00:04:38]It's got a little threaded insert in there. There is, now it's been removed, um it's held in, incidentally, by little blobs of silicone at the side as well, just to keep it secure onto these pins.

[00:04:49]But, there is this black membrane. Is this carbon? Not really sure. We'll find out when we open it cuz it is, indeed, time to get crunchy. Let's start crunching.

[00:05:04]Right, this is promising. Oh, that was easier than expected. Oh, there's a circuit board. Oh, that's just a membrane. That is literally Is that just a carbon membrane?

[00:05:15]Uh meter, hold on. Let's get the meter in here.

[00:05:19]And I'll I'll bring the meter in. Oh, I'll dust the meter off. It's It's gathering dust.

[00:05:26]I'm just brushing the meter off here.

[00:05:28]You may hear the brush in the background. Here's the meter looking absolutely huge. Let's zoom back out again for that reason.

[00:05:36]And we'll go to continuity, I think.

[00:05:43]And we'll just initially go on to this side, which is the side Okay, so that is a fairly high resistance.

[00:05:55]It's a a modest resistance. What about from one side to the other? If I just I've just poked a hole right through this.

[00:06:01]I don't know what this is. I think it might actually be a sort of Uh right, so it is just I'm not sure what that membrane is. I'm guessing it might be Let's just push it out completely.

[00:06:17]Get the finger into it. Well, that's not working. Uh hold on.

[00:06:21]pen That's a rubber. I think that's graphite rubber or something or carbon rubber.

[00:06:33]And that's literally it's one electrode, but it's also Why is it permeable? And what's that mesh there? Does it actually vent gas out this side as well? I wouldn't expect it. I don't know what this is for. Why there's that little hole.

[00:06:45]Um yeah, that's strange. Anyway, let's try and get the circuit board out. Let's use one of the probes to lever out, which is not what you do.

[00:06:55]And we have one electrode going down to there. That was going down to the uh rubber.

[00:07:03]And it's the red wire. That doesn't necessarily mean positive.

[00:07:07]How is it attached to that?

[00:07:10]Glue or something?

[00:07:12]And the other electrode, which is also red, and therefore we can't just assume the the color. Uh what does it say here?

[00:07:23]The one going to the graphite or the carbon is positive and the one going to the I don't know. Is this zinc? It could be zinc carbon effectively.

[00:07:36]Um I'm going to take a wee shaving of this and light it and see what happens.

[00:07:42]Here is a little shaving. Let's light it with a super duper blue torch and see what happens.

[00:07:48]It's just melting back. It's just kind of It's not doing anything exciting.

[00:07:51]It's not like it's uh It's not doing a sort of magnesiumy type thing.

[00:07:57]Not sure. Zinc or aluminum? I don't know.

[00:08:01]What's the best way to determine that? I shall put a little bit of this into sodium hydroxide. One moment, please.

[00:08:10]Okay, let's put some shavings into this and see if it bubbles.

[00:08:16]It is bubbling. So, that could be aluminum.

[00:08:20]Hold on. I'm going to have to research this. I'm going to have to ask.

[00:08:24]I'm going to have to ask the Google.

[00:08:26]And see does zinc also bubble?

[00:08:29]Can you see this a bubble coming off that? I don't know if you can even Yeah, you can see the bubbles coming off that. So, it might be aluminum, but I'm not really sure. Uh let me just go and check that.

[00:08:42]Okay, Google says that zinc will dissolve in sodium hydroxide. So, that wasn't a great test. However, it also says, I'll just put that blade back in the position, that if you tap it, it will sound denser. It says it should be it should feel a lot heavier than aluminum. This doesn't. This feels like aluminum.

[00:09:01]I'm not really sure. Very hard to say.

[00:09:04]It might be a custom uh alloy that they've created just for this.

[00:09:10]Um I would have thought that uh aluminum would potentially Hmm, tricky. I'm just going to scrape this.

[00:09:20]And see if it oxidizes quickly. That's not a great indicator of the of the aluminum. Certainly, it scrapes easily, but then so does aluminum. Zinc or aluminum? I'll let you guys weigh in on this because I'm not sure what this metal is. Okay, tell you what. Let's take a look at the circuit board now.

[00:09:37]One moment, please.

[00:09:40]And resume. I have reconstituted the battery by cable tying both sides together. Notice that well, I'll zoom down in this so you can actually see that. I'll just hold the squishy cell here. Notice that the construction of the rubbery uh carbon side is this conductive mesh in the middle with the rubbery carbon material on both sides.

[00:10:03]It's also worth mention. I think this is a zinc carbon battery.

[00:10:06]Uh zinc carbon cell should I say because it is just a single cell and not a full battery of cells.

[00:10:12]So, let's get this on to it. We'll put the negative on to the zinc and we'll put the positive on to there and we get about 1.48 volts. That's like a a 1.5 volt standard uh wet cell. Interesting. Now, I'll tell you what. Let's short it out.

[00:10:31]I'm just going to put this straight to the milliamp settings because these cells are notorious for not really uh putting out a huge amount of current.

[00:10:41]So, here's the milliamp setting. Let's put it to DC milliamps.

[00:10:46]And we'll stick this on and see what it can muster. This might seem quite reckless, but I'm confident this is not going to put out a lot of current.

[00:10:54]80 93 94 it's kind of going up, which is odd, but anyway, roughly about 100 milliamps, which is notable because the cell itself seems to be a major current limiting factor in this uh design.

[00:11:11]This is why you can kind of get probably longer life by using less salt if you wanted to do such things.

[00:11:18]Um it's also worth mentioning that the carbon will not really It doesn't corrode. The bit that's going to corrode in this is going to be the zinc. I'll tell you what. I'm going to grab a Leclanché cell. One moment, please.

[00:11:32]Unexpected, but here is the Leclanche cell. The black stuff is there for a reason. It's picture It's to stop all the crystals growing out. It kind of inhibits that. But we've got a big glass jar. We've got a ceramic tub. That's the electrical separator. Filled with carbon granules with a big slab of carbon right down the middle of those carbon granules and little vent hole at the top to let all the air come out and the liquid flow up. And then we have the disposable zinc electrodes that you could scrub and clean them.

[00:11:59]Um but ultimately, when they've uh served their purpose, uh you just replace them. And the liquid that used to be put in these was ammonium chloride, sal ammoniac. Uh I really should reconstitute this cell at some point. So we can observe a real vintage Leclanche cell. Look at the wee brass nut at the top, the thumb nut. That's so cute. Um these were used in maid call systems in the UK. This is really old. This is Victorianish. It's ancient. Uh when you wanted to be served by the maid, ding dong. Oh, come here and serve me, you Yes, indeed, cuz that's what it was like in the UK. Uh right, I'll just put this out of the way. One moment, please.

[00:12:39]Okay, now that piece of vintage apparatus is out of the way. Let's explore. Something worth mentioning.

[00:12:46]This uh has the bag sealed onto it.

[00:12:49]And ultimately, um the front cover here is just basically just clipped on on over the top of that. I'm not sure what this bit's for. Is it to allow movement of the membrane or if it leaks, is it to allow something like that? Or was there going to be a little sounder put in here? Not really sure for summoning assistance. I don't know.

[00:13:11]But here is the circuit board.

[00:13:13]Here's the output from the improvised wet cell.

[00:13:16]And it is decoupled with this little capacitor here. And then there's an H33S buck uh buck boost converter, which is only effectively using uh could have been done with three-pin component, but a 3.3 mega Henry inductor and it shunts that to the zero volt rail, build up magnetic field, then opens it, lets it collapse and diverts it out to this rail, which gives the positive supply.

[00:13:42]It monitors voltage between there and the zero volt rail and when it goes to above 3.3 volts, it cuts back and stop boosting. So, it just basically regulates, but there's a chance that this may not supply enough current, the voltage may drop. Hang on. It's really just capping the upper voltage.

[00:13:57]Here is a bit of decoupling. There is a anonymous microcontroller with a the positive and negative. The three pins here are common for driving the LEDs direct with no resistors, hence why it's relying on the cell for the current limiting.

[00:14:12]And the switch bridges this pin to the zero volt rail. That's it. There's not really much to it. Let me show you the schematic.

[00:14:21]So, there is the improvised zinc-carbon cell.

[00:14:24]Uh here's the decoupling capacitor.

[00:14:26]There's a little 3.3 mega Henry inductor. There's a little boost regulator for the up to 3.3 volts.

[00:14:32]Couple of decoupling capacitors, microcontroller, button to the zero volt rail, probably internal pull-up resistor, well, definitely an internal pull-up resistor, and then just the three LEDs cascaded. One other thing I could add here is to go like that. There we go, cuz it is effectively three pins come together. Bit naughty, but not that bad.

[00:14:51]Um it's a a way that you can boost the current output that can be switched by the microcontroller, but you just have to make sure when you're writing the software that one goes positive and one goes negative, high and low. You have to make sure they're all just switched simultaneously in tandem to actually drive the LEDs. Uh but that's it. It's an interesting thing. Um suppose it's useful in an emergency. Uh and quite novel to see the use of the improvised cell like this.

[00:15:21]Ultimately, I guess the lifespan is the how long this piece of zinc lasts, which is presumably the the lifespan that they're basically specifying there of up to about 100 or so hours of light.

[00:15:37]But there we have it. That's what's inside these emergency water powered, not water powered, lights.