Hello! Can I charge this super capacitors with this an Lto battery? The super capacitors, uh, six in series. So the maximum voltage of this is Uh 16.2 Vols Now the Lto battery is just 2.4 volts. Uh, it's probably a bit more than that at the moment. CU It's fully charged.

So uh, 2.8 but it goes down to 2 volts And so what I want of course, is a boost converter to boost this low voltage up to the 16.2 volts I need to charge these super capacitors. but there are very few boost converters that can operate down to 2 volts. However, this one can. This is the Zks S4 and you can see that the input, uh, that's the input side.

There is 2 volts to 24 vol volts and the output is 3 volts to 30 volts. So yes, this can actually operate with an input voltage as low as 2 volts. Now, of course, Boost Converter steps the voltage up. so we'll be stepping up from 2 volts to 16 volts.

actually a bit more than 2 volts because as I say, the battery is charged. Um, but you don't get out for now. So uh, whereas you get a voltage step up, you'll get a current step down. So if I'm charging the Super Caps at half an amp which is what I'm intending to do, then this 8:1 ratio means I'll have four amps at the input.

But this is actually quite a capable unit despite its small size. The input protection fuse is actually 15 amps now because the input voltage is so low. Uh, you need a protection against that falling further because it doesn't have to fall far and you're going to get a bigger Step Up ratio and of course then a bigger uh demand for current at the front end. So this has a mosfet which is an input side disconnect mosfet and there's a resistor Network down here.

and if you add an additional resistor which I've done here I've actually disconnected it at one end. Um, you can set this so the cut off voltage is 3 Volts for Lithium Nmc cells? Well, a single cell. Um, but I want this to work all the way down to 2 volts because I'm using this Lto cell. This cutof mosfet uh also works as an input uh, reverse polarity protection device.

So though, uh, you can't really get the input polarity wrong Now this also has Uh current constant current control as well as a constant voltage control. So you got current limit limit, and voltage limit. Uh, what have we got here? We got two mosfets. This is like I say the input cuto mosfet.

This is the Boost converter mosfet. This is the diode inductor here. Um, so I'm just going to draw a simplified schematic of this with just two components, the inductor and the diode. Simplified schematic of a boost converter inductor, diode and uh, here we've got some stuff stuff like that ground.

um so what you have to be careful of is when I'm charging my super caps these, um, they could be at 0 volts. My battery on this side is going to be. well, it's going to start at 2.8 volts. I need a ground there? don't I Um, now that means that uh, the 2.8 volts can flow or current can flow through this path.

Uh, stuff you can pretty much ignore at this stage and you will have no current limiting while the capacitors are at the input voltage minus the Diode volt drop. So you could get tens or more of Amps flowing through this path. So although this device has current limiting, it only has current limiting when the output device is at or above the input voltage. minus this.

Uh, Vault drop right without further. Ado Let's get on with hooking this up. So I have made these Uh Lto battery stands almost. These were very large uh crimp connectors, but I flattened them out and drilled holes in them.

Uh, so negative will go on this end. I've got some big M12 nuts. Okay, tighten that up with a very large 9 19 mm spanner. The reason I put a fuse in here is cuz I was thinking when I'm moving this thing around on the desk and these wires are just flailing about, there's every possibility they might touch and so I'm doing this without the fuse fitted.

but I'm going to pass these under this the battery that's going to sit there and then I can connect these to the input of the Boost converter. I Really don't like these little terminal blocks. but I have found that these things which are Crim connectors with just a a thin blade. it's marked with little Um marks.

Oh, that's all of them falling out. Yeah, these little marks so that you can cut them down to the length you require. So I've cut these ones down. let's shove this uh up here as far as it'll go.

and then I'll sit it down on some blue tack just to hold it in place. Uh, while I'm experimenting with it. Okay, that looks good on the input side side now. I need to fit the fuse so I'll pop that in there and we should see the green light come on.

which indicates that there's a voltage on the output. So I've made up. uh, these two cables banana plugs to these little blades. So I'm going to cut these blades down to fit in these terminal blocks.

Uh, I think about there, should do it and the other one. I think it's about there. Okay, I'll stick these in the output of the Boost converter and then we'll put a DMM on here and measure the voltage coming out of this thing. Now, despite this uh, boost converter having current limiting what I can't do and I've taken the fuse out to make sure this doesn't happen I can't short these output connections together because this boost converter has no ability to reduce the voltage at the output below the voltage at the input minus the diode volt drop.

So you if I shorted these and the fuse was in, then I would simply blow that fuse. Uh, the input 15 amp fuse also protects this device. So I want my meter on volt? make sure I'm not in the 10 amp connector. Plug this in and see what we're getting on the output.

Okay, it's set to 8 something volts. So I need to raise the voltage of this up to Uh 16 or 16.2 for that super capacitor bank. So stick my trim pot twiddly thing in here and raise the voltage up to Uh 16.17 That'll do and I'm going to take the current limiter right down at this stage. Oh, the light has actually come on.

Oh, it can't even maintain an output voltage. Uh, when you've got the current limit pot set to minimum. so I'll set it so that it can, at least, uh, give us the 16 volts on the output. but at whatever the minimum current setting is and we will measure that.

So now I just connect the super capacitor Bank to the output of the Boost converter and we can start charging it. Well, not so fast because like I say if this Supercat bank is at zero volts and it might be um, it probably would be if it had something following it like another power supply to pass the charge onto something else. Um, then we'd get an allight current flowing through this device and the input fuse would blow while this climbed up to 2.8 volts minus the diode drop which is if it's a silicon diode, it's 6. So 2.2 volts.

while this climbed to 2.2 volts, the current would be unlimited. So just to satisfy my curiosity, let's see what the Supercat bank is charged up to. uh, and well, as it happens, it is at about two volts. So I probably could connect it directly to the output of this thing and it would probably be all right.

But I'm going to take a precaution. Uh, Anyway, just for the first part of this charge. and that precaution is I'm going to use this Uh 24v vehicle bulb as a series resistance so that, um, this is inherently current limited. Uh, we shouldn't see this.

Oh, we might see this light up depending on what I set the current too, but let's put that in circuit. I'll put that in the negative side um of this circuit. so let's connect that to there, put it off to the top there. Okay, so uh, negative to the bulb, positive to the super caps and then I'll use another positive to go from the other side of the bulb to the super caps.

Let's plug it in and we've got a the red light. Come on. the green light has gone very dim because now it's not at 16 volts on the output. it's at two volts or whatever the Superat bank is and the red light has come on to say that it's current limiting now I don't know how much current it's passing through to the Super Caps yet, so let's measure that.

Uh I got that bit wrong I think I put a yellow wire from the colors are relevant, but um I want a black wire cuz this uh bulb is in my negative. First thing I want to do actually is measure. Make sure I'm not in 10 amps. Yeah, measure the voltage across the super cap bank and that's 2.34 and going up quite slowly.

Um, that means that we're past the point where um, there could be a problem with very large currents going through the Uh boost converter. but what I want to see now is what is the current. So I'll get another. DMM Now this superc cap power Um bank has these resistors which are 1 0 so that's 10 ohms.

There are four of them in parallel so that's 2 and 1/2 ohms. The capacitors are 2.7 volt so let's call it 2 and 1 half volts. so that's 1 amp. This um offsetting circuit can dissipate 1 amp.

so I can charge these at up to 1 amp. I mean I can charge them uh at much higher current initially. but when they get near the top and the blue lights come on 1 amp is the maximum. Now this 8:1 ratio.

Approximately assuming this cell drops in voltage, it won't drop very quickly because it is quite a big cell. It's 40 amp hours, 996 wat hours you can see there. Um, uh. so 1 amp on the output will mean8 amps on the input.

That's well within the limitations of the 15 amp fuse, so that should be fine. Uh, I'm just waiting really for this to get up to to about 2.8 volts cuz then I know I mean I know we got the diode volt drop. Actually, it should be fine at 2.6 volts. Okay, I'm going to take the bulb out of circuit and put the ameter across the bulb connections actually because that's the easiest place to measure the current.

So I'm measuring the current in the negative. so I thought I'd Do it all with black cables I don't quite have enough. So I'm going to have to use this. uh, yellow cable.

So that's the 10 amp connector. Uh, okay, so that's the current. Oh, it's tiny. It's 20 milliamps.

So let's raise the current limit pot to um, why isn't that going up? What's going on? Actually, that's not right, Is it? it's not 10 amps And positive, it's 10 amps in common I think Okay, that's more like it. Um, we've got 180 milliamps. This is current limiting cuz the the red light is on. but let's raise that up to about 1 amp.

I'll have it just shy of 1 amp. Actually, we'll go for 900 milliamps. Okay, so we're charging the cat bank at 1 amp. the voltage is rising fairly quickly.

Uh, that's gone off. so let's press that to turn it back on. But uh, that's it, isn't it that is charging a 16.2 volt Supercat Bank from a very low voltage cell Uh, 2.4 volts nominal using this Uh ZK S4 Boost Converter: Um, being careful that we don't pass very high currents through it because it is essentially this in topology so there's no current limiting until you're actually trying to boost this current up to a sorry, this voltage up to a higher voltage. And that means um, that you can control the operation of this switch.

This is essentially a switch Um, and therefore control how much higher voltage you get on the output of the Uh inductor that then passes through the diode into a capacitor. Actually, this device I didn't point it out, but it has what looks like a pie filter on the output. has a capacitor and then an inductor and then another capacitor. so it looks like it has a very nicely filtered output.

Now something else I Have to watch I Believe this normally has a heat sink stuck on top of the three Uh semiconductor devices there. the input cut off mosfet, the main switching mosfet, and the Boost converter diode. So I'm just going to turn on this thermal imaging camera cuz I Just want to check that we don't have high temperature temperatures on any of the components on this board running at. um.

Well, of course, 800 milliamps at the output at 6 volts is going to be a lot less current at the input than when we've got 800 milliamps at 16 volts. So we should be okay now. But of course the current on the input is. as the voltage of the capacitors comes up, the current on the input is going to constantly increase.

So let's see what temperatures we've got. Oh, there's nothing to worry about because the maximum temperature is less than 30 and it looks to me like what's getting hot is the diode actually? yes, the right hand of those three devices, which is the Boost converter diode. Okay, that all looks good actually. I've just noticed that on the input side I've got a 4 amp fuse in this holder.

but these are funny fuses. They they've got little light bulbs in them so that they sort of light up when they're blown. That's the idea. Anyway, they're 12vt light bulbs and I Got a funny feeling that these all measured much higher currents.

They could sustain much higher currents than their indicated value. So um, we'll keep it at these settings for now. but if it all suddenly switches off, it's probably that fuse that's blown. Something else you have to watch with this boost converter is it's got a USB output, but it's not 5vt regulated.

it's just simply whatever you're putting out. um, on the output connector. so it will be 16 volts when we get there. It's currently 8.4 volts, so just be aware that this is not specifically 5.

Vols Um, if you wanted to use this for charging a phone or something, I'm not sure I would want to do that. Um, you'd have to make sure you set the output voltage to 5 volts or 5.2 or something like that. So uh, yes, it is possible to use uh this. Buck converter.

sorry Boost Converter Boost Converter which has a very low minimum input voltage to take power from this very low voltage Lto cell nominal 2.4 I've just measured this actually and it's at 2.6 volts at the moment. Um, yeah, to take energy from here and put it into something which has a much higher voltage by stepping it up to that voltage. But I'll come back when this has got to 16.2 volts. This current appears to be dropping off ever so slightly, so maybe this is not precisely a constant current pot.

Um, but it's not far off. I Just wanted to recheck the temperature of the diode. This would be better if it had the heat sink across there to distribute the heat across all three deves, and of course, to dissipate the heat. but it's not too bad.

It's 35 on that diode, actually. the temperature on that Central on that switching fet is about the same, isn't it? About 35? so that's okay and we're now up to 12 volts. I've just been um, seeing what the temperatur is on this input fuse and it's not hot or warm so it's 17 or 15. Um, but I just remember these, even the sort of low amp ones three or four amp I seem to remember they were still good at about 10 amps.

they're just not very good fuses and it's now the switching moset that's the hottest component cuz the diode's over here and the red box is there at nearly 40. but I'm still not worried about that temperature. uh, 14 volts. It looks like.

um, the Boost converter is now going more into voltage limiting than current limiting cuz the current's dropped right off. Uh, we're up to 16 volts. I'm surprised I haven't seen any of these blue LEDs coming on yet for the protection circuits I'll wait until they do. I Just um, tweaked up the voltage pot slightly because I wasn't quite getting to the point where these blue lights were coming on.

but now they're starting to come on so that you can see that the protection circuits um, are starting to protect the super caps when they get up to 2.7 volts. And of course, because um, these circuits are using energy, the current is now climbing back up. Yeah, these are all starting to come on. So that's it really.

That shows that I can use a 2.6 volt uh input voltage source this battery. um to charge this up to 16.2 Vols Uh using this Uh Boost converter which has this very low input minimum voltage capability. But there are certain caveats. but that's the end of the video.

So oh, why is that gone to Uh Zero? What's the names? That's a mystery.