Good Morning All this is a Rock Trail outdoor hand warmer which I bought from Lidl about six months ago now. Um for about 12 pounds 95 I think so. This is another example of a contact heater. A conduction heater.

Uh, very much like the electric hot water bottles I showed in the last video, this thing imparts its heat to your hands. Oh look, it's all taken to Pieces Um through conduction. three year warranty on this device and it lasted six months so it didn't quite make it to the three years. um.

and I've had to break it apart because, well, it was getting hot. This is just a decorative band which went round there to hide this recess. It actually was quite difficult to get apart because all these little lugs really were a one-time hit. You're not meant to take this thing apart, certainly not easily.

Anyway, so what do I mean by it got hot? Because surely it's meant to get hot. Yes, it is these. um. side panels which are actually aluminum.

I Think they're metal. They have little heating elements and you can see the heating element. uh, their thick pair of wires going up to the PCB But it wasn't these two heating sides that were getting hot. No, it was the printed circuit board.

and as well as getting quite warm, it was also starting to smell of burnt electrical stuff. You know that sort of smell where enameled copper wire is burning and I'll show you the fault as it is. Now, if I plug the battery back in. Uh, you've got three blue LEDs here and normally that would tell you how full the battery is.

Uh, it isn't because the battery is actually quite empty now. No amount of button pressing or pressing and holding does anything now. and if I leave this for any length of time I mean it's not so bad now because the battery is down to about 2.8 volts. But yeah, something was getting hot and something was smelling a bit electrical.

It does actually look like the hottest part. I'm shouting a bit because I'm using internal mics. The hottest part of this might be the inductor. and certainly the smell is a bit like hot enameled copper wire.

It's hard to pinpoint it exactly because I'm jobless. I'm getting how to focus on the thermal imaging camera. There is heat in the center of the board as well. Ah, which would be the mosfet.

the Um A2 Shb mosfet and this problem occurred I think because of the nature of this USB C input and output. The point is, this thing is charged through USBC but it can also act as a power bank and Supply power through the USBC So it's both an input and an output. and there were occasions where this wasn't really sure what it was doing, whether it was taking power in or putting power out. So for example, my RAV Power power bank which has USBC if you connected these two together, the hand warmer would always charge the power bank, not the other way around and this power bank has a feature.

If you press and hold this button for 10 seconds, it will reverse this socket whether it's an input or an output. but this thing never really understood that and I could never get this power bank to charge this hand warmer stroke power bank. and so I'd try and charge it with this uh, small Jackery power station. and if I connected this with the cable that came with it which is this little short a to C cable um, with this USB section off, then the Rock Trail would simply back feed the jackery light up the LED but it wouldn't charge and then in fact doesn't matter whether you switch this on or off, it still wouldn't charge.

You had to actually switch this on first and then plug the Rock Trail in with the 5 volts on. otherwise this just wouldn't take any charge. It was very temperamental and then I tried to charge the Rock Trail I think from the USB a output from here and I was definitely using this illuminated cable and I think I was either using this or possibly this I can't remember but I plugged it into here and the three lights came on and the button wouldn't do anything very much as I showed you just now and then it started getting warm up at the top here. not from the heating panels, but from the PCB and then it started to smell.

And that was the end of this. So that's it. It's dead. We can do a tear down now.

Now the question is, do I take this back? Sort of just close it up and pretend it's uh, not been taken apart. Get my 12 pound 95 back. Or do I make a tear down video which quite possibly will earn 12 pounds 95. This will be destroyed in the process, of course.

Uh, doesn't really matter either way. So I think the first thing I'm going to do is attempt to pull out these uh, thermistors on the end of these pieces of enameled copper wire. Oh, they're quite well stuck in there, aren't they? What about this one? Is this one going to come out? Yes, this one's coming out. and as you can see, there is a little bead thermistor on the end of these enamel copper wires.

So if I can get the one out from the battery, I can actually take the battery out of the unit, let's do that. This one's proving to be a bit stubborn. so I'm gonna have to use a bit of force on here and Trent yank it out. It really doesn't want to come out there.

it is. So again, another little bead thermistor on the end of the enamel copper wire. Okay, now the battery can come out and so yeah, it's pretty symmetrical. You've just got a heating pad and I'm pretty sure this is an aluminum plate.

It's sort of got this plastic rubberized coating which is starting to peel off in places. and you can see that it's metal because there are little lugs here that are bent over through holes. So I could take that out actually. and we could take a look at that.

Yes, I Just need to bend these metal lugs up and that plate should drop out of this half of the hand warmer plastic body. can I push it out like this? Yeah, so oh yeah, that's quite sharp. That's definitely aluminum. All right, that's off.

Um, yeah, it's a very simple heating element. It's on a flexible PCB It looks like I Don't know. would you call that a printed circuit board? It's obviously photo reproduced in some way. Um, I Don't know whether this is a metal element or carbon? don't know.

See if we can peel that off actually. But yeah, it's very, very simple that's just stuck on the underside of this piece of metal. There is an attempt to separate the heating pad. Oh, there's actually a little bit of stuck on foam there separate it from the battery by these ribs.

So at the midpoint there, the heating element is probably about five millimeters away from the battery. There's also this bit of foam, although I think that's primarily to hold the thermistor against it. Oh, lots of details on the battery. Let's have a look.

so. Lithium Ion Rechargeable Battery Model Icr I Can't quite remember what Icr means I think it's Lithium Cobalt round I think the r is either round. in other words, cylindrical or rechargeable. Uh, 18650 two pieces.

they will be in parallel I assume 3.7 volts. Yes, 5200 milliamp hours. Yeah, so they'll be Uh 26. Is it 26 100 milliamp hours each? 19.24 Watt hours Battery Company Limited Do Not disassemble right? Time to take the PCB out.

Um, it's quite small. Doesn't look like this much on the rear either. But we'll see I wonder whether the enameled copper wires, you see, the heating elements and the battery are connected on these beautiful little Jst connectors. So they're mini ones? I Think they are.

They might be two Mil, but are the enamel couple has just soldered on the back? Yes, they are. Isn't that disappointing? I Mean actually, this thing was quite clever. Um, these are dual color LEDs So you've got the blue LEDs which showed you the battery level. Um, and there was also a red LED in here and that would show you the heating mode.

So one LED was low, two LEDs medium, and three High switch on the back which was coupled up to the switch there and a couple of transistors. But that's all that's on the back apart from the connections for these three thermistors. But when this thing was heating the pads, yes, there were three temperature levels for the three heat settings, but it also seemed to affect the low temperature point at which this thing cycled on and off. Because it didn't leave these things on all the time, it would raise them up to a certain temperature and then it would shut them off.

and then only when they dropped back below a certain temperature as measured by these little thermistors would this thing turn back on. And I used to take this thing to bed. Actually, this is a very cold house and you needed a bit of warming up to fall asleep and I'd often leave this thing switched on all night. Not a good idea taking a Lithium battery to bed and leaving it switched on all night.

But um, yeah, and I mean in a warm bed? This thing on setting one never came on, so it was quite happy just sitting there all night and it didn't drain the battery. It didn't really do anything, just gives me that initial warmth to warm my hands up when you get into bed. And yeah, your hands or your whole body's all cold. Anyway, back to the electronics.

So what have we got on here? We've got a little chip there. An inductor here. 2r2 what's that? 2.2 micro Henry Something like that I Did feel that the smell of burning might have been the enamel on this inductor, but I'm not actually sure that's the case anymore, but certainly this doesn't work, so it was killed off. Buy whatever I did to it.

Let's take a look at those two chips, right? We have an unmarked microcontroller that's the 16 pin device here. I Assume it's a micro controller. Um, the little power controller chip next to the inductor is an Et89742 I'm just printing out the data sheet for that and then there's an A2 Shb slot 23 on the top and a couple of S12 transistors I presume on the bottom. We'll take a look at those in a moment.

Okay, so the ETA 9742 is pretty much a made for USBC bi-directional power bank type devices because it's got um, bi-directional Power conversion with single inductor. So it's a three amp switching charger, but also when it flips around the other way, it's a 2.4 amp boost with an assistant for a battery measurement. Three LED indicators for battery level. so pretty much made for this application.

Uh, up to 96 efficiency. 5 volt synchronous boost switching charger. Yeah, so made for the USBC type bi-directional Port application. Yeah, for charging.

It uses a proprietary control scheme that eliminates the current sense resistor for conventional constant current control. It can also output a 5 volt voltage in the reverse Direction by boosting from the battery. It only needs a single induct to provide Power bi-directionally with a proprietary automatic mode detect and switch scheme which works most of the time. But if you confuse it, it blows itself up never to work again.

So if this little chip does all of the USBC bi-directional power, battery charging and all that stuff, What's the microcontroller for? Well, of course, you've got to measure the temperature with these three thermistors, so there'll be three analog to digital inputs in use there. Also, of course, you've got a pulse width modulate the power going to these heating elements to provide the three different temperature levels. So that's what the micro controller is doing. It's doing all of the heat related stuff, so there it is.

That's what's inside a Rock Trail uh, hand warmer stroke power bank. There's no way I can take this back. Now it's completely dismantled, so do us a favor. Would you and the like button? hit the like button and then hopefully I can get this lot paid for.

Okay Cheerio.