Shorting out a fully charged cheap lithium jump starter. (It didn't end well.)

This is a fairly common eBay style

jump

pack with

lithium

cells inside and is the type that uses these standard cables. I already have to take one of these apart and it was given to me by a local guy called Andy who bought it a while ago and used it a couple of times and then it just stopped working, so the circuit, when you put it on charge, when you plug in a USB cable, it starts trying to charge but when you press the button It kind of acts very randomly and when you press the button on this side, to activate it, you can feel the button click and I have tried

shorting

it and trying to track it , but it just doesn't respond to the button at all.

It's interesting to take a look at the circuits, now you might be wondering what kind of protection is in these, you know, to protect against over current and over discharge of the cells and the answer is none, no, I can't see anyway, maybe tabs. it will just burn out the batteries or something but let's take a closer look so the circuit board has four connections and that represents one from each end of the cell the red and black and then the blue and yellow are the connections intermediates of the uh, a series of cells in the battery and that means that you can balance the circuits and I was expecting a balance circuit in this, but there is a balance circuit that is based on the cell protection chip dw1 uh, there is one in this side and there are two on that side and there are a lot of Circ around them with a lot of transistors and I was trying to figure out what it was for and one of the thoughts that came to my mind was that maybe it is doing some clever trick that if you put in the 5vt The supply is actually switching through the cells and using all those transistors to charge the cells individually, uh, switching them in the circuit, but when testing it, uh, when I connect the 5 Vol, current flows in the wires red and black. and the voltage is very high, about this 12 volt mark and this inductor gets hot so I think this inductor is being used to increase the voltage and charge all the cells at once and so I assumed that the dw1 chips the chips Lithium protection packs simply act as a sort of discrete balance circuit which, in a sense, I would have thought they simply use a balance chip like that found in standard H

lithium

protector packs, especially since it doesn't carry any significant current. because all the current coming out of this is coming directly from the battery tabs, as far as I can see, we'll find out shortly if that's the case because I'm going to open this up, which is probably a terrible idea, but that's what which we do, the chip on the circuit board is a jsy 3050 paa and the circuit board is extremely difficult to trace because it is shiny and black, let me sit this on top of this, it is very shiny, it is really very fatiguing.

Try it and you will know that even with a magnifying glass you are trying to follow the traces back, they are small traces and there are a lot of plated through holes and it just

jump

s back and forth all the time and the black color it just creates. really it's maybe that's the design maybe that's what makes it very difficult to reverse engineer this uh I couldn't find any data on that chip which is disappointing um I guess the inductor then it may actually be pressed to go into action a second time, uh, to regulate the voltage down to 5 volts, but I couldn't test it because I couldn't activate the output and I tried to trace it, I thought maybe the switch is faulty, but it's strange that the switch It seems to go in both directions, it seems to go to transistors.

I'm not sure if they are just using it as diodes or I don't know if they are giving each one. component a multi task in a you know, trying to reuse a lot of the pins for inputs and outputs, there are two mosfet packages, there is a dual mosfet in there, I think it's a dual mosfet and another one, right behind the cells, and that was which made me think. which could be H changing the cells, but it doesn't seem to be, it's difficult, very strange circuits, very dead circuits too, so here's the interesting thing. Let's open this now, another thing is this battery pack here, uh, if I open this battery pack. above the battery pack I don't mean what I'm talking about the diode pack because it is a diode pack again, this is a bit that is designed to stop the alternator once the engine has started, it is to stop it again by feeding the lithium cell and overcharging it.

So if I open this up, it's a very similar build to the other one I opened, except it's all on one circuit board with lots and lots of vent holes, maybe unless they're designed to be used as plated through holes for heat, uh, single sided board. uh there is no major heat sink on the solder and I must say I tested this and there was current leakage in both directions. I have a feeling this is already kind of toast, but there's something here we really want, so let's find something to open this up. top I think scissors might actually be a good option here, try not to stab the lithium cell.

I tried the lithium pack. I basically made a small adapter based on a USB charger and then filled the end because I noticed that the two outer cells in the pack were charging

fully

, but the middle one wasn't reaching the maximum voltage, so I think this circuit is completely screwed. and it's controlling that but basically I treated each cell as an individual cell with this and I was able to charge them individually and test them so I did a full charge and discharge test and it came up to 1.6 amp hours for the middle cell so let's get started cautiously cut into this package a lot of tape, a lot of insulation, a little strange, where is my where is my?

Yeah, I have a can on hand in case this thing goes thermonuclear, so I see layers of insulation here. How do you solder it on the tab? I mean, it's a pretty big tab, it's a big tab, it's about half. an inch, between 12, maybe, 14mm, 15mm wide, maybe the tab coming out of this cell, so it's obviously designed to handle a lot of current and they've put in a lot of insulation that I'm removing, which is probably Something terrible about the adjacent decent connections here. What is the worst? I could pass Llamas oh, they're big, aren't they?

They are really big terminals. That's essentially it, there are the insulators and they have actually been folded. They have this ort. of laminated card, they put it between because there is a connection, a high current connection on the other side of the package, they actually put the cardboard between these two cells here and then they folded it out. to protect that and the same on the other side and that's all there is to it, it's really just bare cells just sold along with links, yeah which is pretty much what I expected, I'm really just being careful here, no I want to cause a little thermonuclear incident there's not much to see there's not much to see at all so um yeah that's it, it's really just three cells connected in series with the balance wires coming out and just the positive and the negative, just these strong cables.

These middle silicon type wires go to this connector, so when you plug these wires into the output, you're basically running the lithium pack directly through your battery, uh, and if it shorted out, if you literally just put the that way. uh there won't be anything you know the pack is going to go out, it's probably going to get very hot and it may actually burst into flames which seems to be happening very similarly with the failure of these diodes on some of the other ones. packages, it sounds like you know that a lot of these packages actually go too far when people leave them on or rev the engine too much, that's pretty interesting, it's pretty exciting, so I'm wondering what the next step of evolution is going to be. in these.

Also you get higher quality packages, you also get packages that have more inline protection instead of just diodes, they have an active electronic module with relays, but I wonder how reliable those relays will be given that they are dealing with currents of literally hundreds of amps, particularly under fault conditions, if someone connects the wires backwards because the diode is not going to help, you will still effectively have two batteries connected in series and shorted, um. so it should be interesting to see how it develops or will develop or is it more or less like this because this is the

cheap

est way to do it just these super high current packages uh interesting, it's worth breaking it down into pieces so really that leaves the question for us, what would actually happen if this were to short circuit so I

charged

it all the way to the bottom and I actually have 4.3 volts per cell which is a bit naughty and I did a special test charge, a test charge It looks suspiciously like a bit of 15mm copper tubing and I've spaced out a couple of tap points.

I have welded on this just the right distance. I can put these clamps on and by measuring the voltage across this I've already bench calibrated it. Supply and I know that by sheer luck a nice round figure came out, it is h 110 microv volts per amp and I tested that 1 amp, 3 amps and 5 amps came out very consistent, very good and to test I used a higher resolution meter from the normal. using this amical st-9929 and this has the advantage of much better accuracy and it also has a min max log feature so what I'm going to do is put these cables here and monitor when I actually plug this in the power supply what type of voltage you get here, which will indicate the current flowing C, for example if it were 100 amps it would be 11 microns 11 m BTS.

I think so, yeah, it'll be interesting to see, but I. I'm not going to do that at my bank because that would be extremely foolish. I'm going to do it outdoors, so yeah, let's go outdoors and do the test, okay, let's start the experiment, so, I'm not very up to date at all, why? that just blew something is blowing that's intriguing something just blew like a fuse okay in the previous test of this uh the diode pack opened the circuit so let's try it again with a different diode pack oh that's quite a bit of current

well

that's about 160 amps, oh yeah, the P battery s

well

ed, it wasn't that dramatic, it just drained all the power, yeah, it dropped to about, oh yeah, the current really plummeted, to be fair , did not burst into flames.

I can see smoke and I can smell that characteristic smell of lithium packs, sad lithium packs, so, okay, let's do an autopsy on what happened now, okay, let's go back to the bank for an autopsy, first thing I'm going to do look is the diode pack that failed because I have a feeling that because this was based on a printed circuit board there is a good chance that the printed circuit board track blew like a fuse so let's open it up this, just open it with the spudger. I quite like it The way it puffs out there it's burned, yeah I think it's burned, yeah it's burned, can you see that kind of outline that's basically burned like a wick?

I'm not sure if they intended for it to burn like a wick. but has done that H, what about the directories? Were they active at one point? I'll just bring the meter back having said these were a bit devoured anyway so it doesn't really matter, yeah still devoured okay the other pack even survived. although that made you realize that the current selected initially was 500 amps, so if I put this wire here and this one here it shows the super low forward voltage that we measured before and if I change the wires, it shows the proper diode characteristics, so That's impressive, despite the 500 amp increase, I

didn

't say that, let me think that each of those diodes was rated at about eight amps, right?

I'm trying to remember, I'm trying to remember what the rating was on those dial packages. um it was 10 amps per di so oh it was a total of 80 but so with a peak current of most of 800 amps in this case you only saw about 500 amps very briefly and the reason why the one who only saw that current very briefly long enough to burn this track. Like a fuse, it's because one of the cells, not all cells 1, two, 3, the top one is the one that actually failed and obviously the current is limited by doing that and the voltage that goes through it now It is low.

They are about 1.6 volts, but the other two cells are just as flat and slightly bent partly because they are inflated. They're still measuring over four volts, which suggests that you don't know that a lot of energy was dissipated overall before it decided to sacrifice itself to save the other um the temptation is to look at this a little closer. I really should have put on a glove, right? I'm not sure I should open this H-pack since he might still have a lot of energy left, but then He, he's never stopped me before, that's why I'm so dumb.

Oh, cutting it, cutting the lithium pack with a knife doesn't seem smart to me either, but then again, that sums me up as really recklessly stupid, so let's do it. some cuts inThis is a thick cable, it doesn't look very coppery. I wonder if it's steel or aluminum. I guess it's probably aluminum aluminum. What can I cut that with snips? I'll cut the tape here Deactivate The pack so I need to cut that one too W oh my gosh it's like diffusing a bomb actually it also feels like diffusing a bomb mainly because it's a little lithium bomb because when these things go up it really they go up and, having already proven that you can easily put out 500 amps, that's pretty impressive, let's try to cut that out there.

I'll let you know if it's too hot. I'm just looking around from my explosion containment pie plate. I've seen my explosion containment pie plate, it's not heating up. I'm going to go get my gloves in a moment, yeah, AET gloves are probably a good idea, I don't think so. These gloves are flame resistant, but okay, that's me looking like a tattoo artist again, let's take a closer look at this package and see if we can see what went wrong. This could go thermonuclear again. P dish on hand, yeah, okay, let's open this package. I'm thinking maybe I can't cut it at that end and this end is pretty close to where all the chemicals inside are.

I wonder how much energy is still stored in this, even though its voltage has dropped. I think it probably still holds up. many surprises and as it has already been shown that it can produce 500 amps under pressure, which makes it much more exciting. I wonder if it will show some characteristic, some kind of damage that, uh, no, it's not heating up just to check. Why did I do this? It's so silly, but I keep doing it anyway. I can see the liquid under the electrolyte. I can smell the electrolyte. It gives you cancer. uh, I should have cut this first, but don't worry, I

didn

't.

At the end of the test it was only showing a few amps anyway, although a few amps is still quite a few amps. Ah, that's pretty sure, let's unravel at least some of that lovely smell these produce, probably not good for you, but. Hey, I want to remind you again that they don't actually contain much actual lithium, but this will change color quickly. Separate the separate plates. They are a bunch of separate plates. This is how they get the high current. Wow, it's not just the usual line. it's a little bit of a warm feeling, I think it's a little bit of a warm feeling, but that's okay, so this is a completely different construction, it's zigzagging back and forth with alternating polarity plates, the copper one and I think that there is the other one. based on aluminum with H oxides, that's intriguing and because of course it's inflated instead of compacted all together in a vacuum and compressed tightly, uh, that's effectively made to have high strength, so, in theory, if I had to tighten it well. that down Wait, let's try to get something to hook to these wires here, so let's grab my little little meter.

You could have it with the big fancy M, but let's use this, uh, 20 volt DC, let's hook it up. Can. I don't remember which one is positive and which one is negative, uh, which one it is doesn't really matter anyway, so I'll just continue there and continue there. It shows approximately two volts. What happens if I squeeze it? The voltage increases. this is still

fully

charged

but it's just inflated oh that's a little scary so, yeah that's interesting, the failure mode has been venting, it's gone High Strength and it's effectively shorted out you know, he basically saved the day by sacrificing himself by going high. resistance and limit that current because all the plates have been separated, that's very interesting DED, particularly the zigzag construction, which means, of course, that each of these plates instead of relying on a continuous film has an impedance much slower because each one of these is in parallel it's like lots and lots of little individual cells in parallel inside, which is very intriguing, very interesting, in fact, I cover almost everything.

I think that also means they're probably because they're not swollen at all. Slightly out of shape, but I don't think it's a problem. They've probably survived, although having briefly gone over 500 amps, I'm not sure how happy they will be, but yeah, cool stuff, bonus extra stuff, I'll never learn, no I won't. Hi, I separated some of these boards, I separated all the copper ones into one stack and I separated all the ones that I think are AI Min into the other stack, the other pole, and I thought it's probably pretty safe because, well, what could happen? if they are? with the same polarity, the copper ones just burst into flames and smoke, which was quite exciting, really unexpected too, so now maybe I won't sort the rest in that same pile and I'll keep these away from each other I should