Hi Just a quick video because so many people have asked for an update on the USB power supply or the power supply projects in general. You know I've started two of them and well as you might know, I haven't been doing any work on them for quite, uh, some time. but I am now back into it. So this is just an update on the USB uh, the battery powered USB supplier that I was working on and you've seen this prototype in a couple of videos and uh, I've got some firmware up and running on it now.

So micro Supply version 1.0 and you know it's displaying I can set and display the constant Uh voltage and the constant current modes. so uh, just a little bit of the menu uh interface here I haven't got the full menu done yet but basically uh, voltage at the top. This is currently displaying output volts here and output current I haven't zeroed the thing or anything like that yet. So and this little selection device allows you to select if you press this.

It allows this toggle between volts and amps there and you'll notice if you actually uh, you'll notice that there's a little s there. Well when I let's say we want to set our volts, this is our up down button here. I can just go up like that. So now it's actually displaying.

When you press those buttons, it briefly displays the set. that's what the S is for. briefly displays the set voltage and the Set current. So I can set that 3.25 and 3.34 and I haven't tweaked the thing as yet and you can do.

and if you want to set the current limit, just go down here and you can set your current limit like that. I haven't got the key velocity stuff all set in there, but it does work. just a treat. So that is a little bit on the user interface with this two line by eight character.

LCD it's um, adequate. Yeah, it's it's not. Uh, it's not the best for displaying a whole bag of information, but it is certainly usable now. Uh with this.

So you know I've done some tests on it and I'm reasonably happy with it, But you know me, I'm gonna change it because I originally wanted to put it into this uh poly case here. it was going to sit here I was going to have punched holes and it was going to run from uh, you know, just single cell mobile phone battery. but I decided Well if you're going to make the thing battery powered, it may as well have a lot of capacity in it. So I decided that the mobile phone battery just wasn't You know, really the greatest capacity.

These are only like you know, 12 1400 milliamp hours at tops is really all I could fit into this case here at 3.7 volts of course, single cell. it was going to sit under the board and I was going to have a clear perspex window on the top so you could see the uh LCD and stuff like that. But ah, you know I decided it. Really it.

If you're going to do it, do it properly and get a decent battery. So I Discovered this thing on HobbyKing Uh and the this is a 5 000 milliamp hour 20c Um, single cell Lithium Polymer battery and it's a bit of a beast. It's designed for 20c uh discharge. So um, you know it's a very huge high discharge capacity battery designed for uh, remote control.

Um, you know, cars and other uh, toys and things like that. you can even get like a 40c discharge version. I Mean we don't need the discharge capacity of, you know, 20c because um, even this cheap 20c version at a rated five amp hours? that's a hundred amps discharge. Um, this thing is capable of.

They're absolutely incredible. Lithium Polymer cells let alone the 40c version Double that. Absolutely incredible. So anyway, I thought uh, at the end of this video, um, after I've done a little bit of a rant here I on the update of the power supply, I will test the capacity of this battery at that lower C version.

so stick around for that at the end. But yeah, these are absolutely cheap. They're this, uh, this one is the highest capacity you can get. It's 10 millimeters, uh, thick by um, oh, 120 or something like that by 40.

and uh, it just so happens that 40 is the exact width of the LCD like that. So I thought, you know I can what I'll probably do is repackage this thing so that the um, uh board, you know, base the design around this battery so that the board is long and thin. Like that, it's the same width. So the LCD sits on there like that there'll be USB charged sockets or other maybe a higher capacity uh charge socket as well on the input and then that would have the screen in there.

Then we'd have the circuitry and we'd have a couple of Um output binding posts on the other side there and it'd be. You know, it doesn't have to be all that thick. You know it's it's only going to be if you take the board. Plus that we can even make it thinner than that.

You know it's not that thick at all. it's not that wide. now. this is reasonably, uh, heavy.

but uh, well, what the heck, you know that's the price you pay for the huge capacity of this thing. But I figure if you're going to have a battery power power supply, you may as well have, um, a decent uh capacity in the thing. So I thought I'd Base it around this and yeah, have a long cylindrical package and that'll mean a custom case for this thing as well. I can get that laser cut out of clear acrylic or something like that.

Like just the exact width so you can see the LCD through it. and I'll have a similar sort of interface with the buttons on the side down here. Like that all along the side here and that should be really quite nice. I'm going to stick with the same LCD I Rather like this, it's quite neat.

It's working quite well. I've got my interface working with it, so pretty darn happy with that. So I think that is the Avenue I'll go with this thing because I was going to make a few changes to the board anyway re-spin it so I might as well re-spin it for a higher capacity battery and a different form factor. and um, really a few of the components on here quite wimpy.

this one because I was basing on the lower capacity battery I really didn't want to go that high in that current or output. uh Power So I think uh with this new one, I might step it up a notch and have a higher output voltage regulator and a higher output switch mode or a higher power capable switch mode converter perhaps. Um, just for some extra output capacity. So there you go.

That's the update. I am working on it and it does actually do the business and work here. So um, for example, like a current I can let's set the current. let's go down here.

let's set it Yeah and I need more room on the board to put proper silk screen labels and stuff? This board was pretty packed by the time I got everything on there I mean there really wasn't much a room left for about silk screens I put the little name on there at an angle, squeezed it in I squeezed in my platypus underneath there and oh, it was. You know, um, it was really quite a squeeze. So hopefully uh, this will give me some more. um, uh.

room to lay out. The components have a bit more silk screen design. anyway. I've got my um current limit set to say 288.

That'll do 288 milliamps, 3.3 volts output I've got a 10 ohm high power 10 Ohm resistor here. we'll whack it across and we should get our current limit at around there you go 288 milliamps so it's a it's working quite nicely and I've measured a bit of its performance and I'm quite happy with it. but yeah, it's a bit. It's a bit wimpy so I thought I'd step it up a bit.

And the good thing about these Turnigy batteries I Took the opportunity just to get a couple of different uh, samples of the thing. Just be careful of these tabs. By the way, you don't want to short them out. that's why they come with these, uh, these protective tape over the ends of them.

But anyway, even this whopping 5000 milliamp hour one? this was only like eight bucks or something. I mean you know, unbelievably cheap. and they have the same size. but in a 3300 milliamp hour? that's uh, cheaper again.

but it is thinner and lighter weight compared to the 5 000 milliamp hour one. But oh, um, I'll design the thing around the 5000 milliamp hour one I think um, you know just because what you can is the same size and shape depends on what price and weight you want. but there's not a huge price difference and they've got smaller ones like this 2200 milliamp hour once again and it's at 20c and I think you can get higher capacity versions as well and it's smaller. And then they step down to this nice little thousand milliamp hour 20c one.

So that might come in handy for some other projects. So these are really quite neat. And by me you know, less than 10 bucks. Unbelievable.

You know for the capacity you can get in this thing and 20c discharge man. anyway I thought I'd do some measurements on that. So I'm going to hook up my BK precision Electronica load here and uh, we'll see and up to my PC and uh, we'll see if we can get a battery discharge curve on this thing one. as I said I don't want to do 20c but let's uh, do you know a benchmark or 1C or something and see what we get.

And by the way, um I think I mentioned that I did actually capture the layout of this board the full layout. So I might even though I'm going to change it, I might still go through and add some commentary on top of that layout and uplight that upload that just like I did with my previous Uh power supply one because they're I think they're really interesting videos just adding commentary to real time or sped up. Uh, real-time PCB layout because you know it took me like you know and you know a five hours or a day or something to lay out this board properly. So I'll speed that up and I might add some commentary now.

I've got my BK Precision 8500 electronic load hooked up to the PC here via the USB adapter which I got with it. you can get an Rs-232 or a USB I've got both using the USB Um and I've hooked it up to the PC software here and as it so happens, the PC software that comes with this BK Precision one. Um, it does actually have a battery discharge application so it allows us to um, specifically set up the battery and discharge it and get the discharge curve and save it. and it calculates the milliamp hour capacity of the battery and so forth.

So I haven't tried it yet? Um, let's see if it works I Hope it works now. as I've mentioned before, one of the really annoying things about this BK Precision 8500 load is that it doesn't have standard these binded posts great look at a big fat chunky ah love the things. great looking knob on them but they don't have support for standard banana. Jacks like that even if you take them off hopeless God So you know I've got like a nice, you know, a high amperage um you know, banana plugged alligator clip cable I can use just for this thing.

but ah man, now I've got to like budget in there with you know, squeezing The Binding post hopeless Now of course you can use your uh constant voltage, constant current, uh bench power supply to charge up a Lithium Polymer cell. but you've got to watch it, it's not. You know, you've got to know what you're doing. Got to set it precisely to 4.2 volts.

You've got to watch the um time limit on the thing and you know, got to be very careful if you're doing that. But what I got from HobbyKing as well for like 22 or 25 bucks or something is a um six cell turnergy. Again, it's the same uh brand. uh Lithium Polymer it does everything does Lithium Polymer Nickel metal, various uh, Lithium types, nickel metal, hydride, nicad, Lead acid, up to six cells.

Of course this is only a single cell. It's really nice I mean you know, for like under 30 bucks, it's absolutely incredible. So that's what I charged up this battery with. It's got the big, positive and negative banana uh terminals out there I Actually, uh, use this to um, charge up my uh batteries from my Quadcopter They're also uh, turnergy.

um Lithium Polymer high discharge batteries as well. There are 35 35 to 45C discharge for my uh, Quadcopters slash Canyon copter. So yeah, really, quite neat. Um, so I have fully charged this battery um, according to this thing.

so let's give it a go. And of course, fully charged. You would expect it to read 4.20 volts and that's exactly what we get. As I've mentioned before, this BK Precision Electronic Load is really incredibly accurate.

as good or better than your typical fluke uh, high-end flick multimeter so you know really Precision bit of Kit And as you can see, it's got the link remote function and on there so it is hooked up to the software and ready to go. And here's the PV 8500 PC software that comes with it and it looks, uh, rather neat. It is actually hooked up so it's actually monitoring in this thing at the moment. You can see that it's 4.2 volts here.

I Don't like these. Dicky readouts. They're actually quite hard to read. They've made them look like seven segment.

It looks worse in real life than on the camera here, but those background ones just really bleed into the the digits. Don't stand out much at all. It's really quite annoying. Um, so they've tried to go all wanky there and they've just failed.

Anyway, You can set it up to various like constant voltage mode, constant current mode, constant resistance mode, and constant power mode. And for those who want to wins that, I'm not actually screen capturing this thing I'm just shooting the LCD with my camcorder. Don't bother. Give me a break.

now. this turnergy battery at a nominal uh, 5000 milliamp hours at 3.7 volts, You multiply those two figures and it's got a nominal watt hour capacity, which is sometimes more important than the milliamp hour capacity. In fact, in most cases it probably is. It's 18.5 Watt hours.

no terminal capacity. That means this thing should be able to, you know, roughly, deliver one watt continuous power for 18 and a half hours. and ideally I'd probably like to Uh, that's how I've tested batteries. uh, battery capacity in the past, tested and specified battery capacities in uh, what hours.

So I can probably do that here with the constant wattage mode. I Could probably get the graph and everything, but I really want to? Um, it doesn't look like you can. You might be able to save the data and I don't know. I'm going to use the battery capacity Wizard and check it out.

It's got a specific battery discharge wizard and zoom in on this sucker and uh it. But unfortunately like it looks quite neat. but unfortunately it looks like it only has constant uh current capability. It doesn't allow you even those Supply This load can do it.

It doesn't allow you to do constant resistance or constant uh wattage, constant power which is really quite annoying. But anyway, it looks like we'll have to get our uh discharge, um, capacity, uh graph in a continuous current because the reason you want to use continuous power is because the DC to DC converter is essentially a continuous power and most, um, you know products that are. You know they're going to operate on an average continuous power in the DC to DC converter is going to have an efficiency loss there, but it's essentially constant power. So that's why it's more useful to analyze and specify your batteries in terms of what hours for a project like this.

But anyway, we don't have that um, luxury here. So um, I You know milliamp Hours will do so. This is has a nominal 5000 milliamp hour at Uh I don't know what that's rated at I Can't get the data sheet if it's actually rated for the full 20c or it's rated for 1C discharge or whatever it is I don't know. so we will just have to, uh, um, just discharge it at one see see if it gets around about that figure.

And of course, once it's finished doing it, it will actually calculate the capacity. It should calculate the capacity in milliamp hours. I Haven't actually tried it yet. Now when you're testing these batteries, you want them, uh, not to just discharge them all the way.

You can damage the thing so you don't want to leave the thing running overnight and come back and found. Oh, it didn't cut out and uh, you know you've ruined your battery. So you want this, um, setting? They've got a safety Vault set in here and you can set that to a minimum voltage and I presume when it gets down to that minimum voltage, it'll just stop. Uh, the discharge and uh, or you can do it based on time.

or you can do it based on capacity as well. So if you know this thing has a certain capacity, then you know, ah, you do it. I the Satan The best way to do it is with the safety voltage. now.

I Don't have the data sheet for this thing. but the next best thing, we do have a Panasonic data sheet for a you know, a single, a similar Lithium Polymer cell not as high a capacity. it's only rated for you know, 2 900 milliamp hours, but it's going to be very similar. and the um I've gone I've done videos on these uh, you know Lithium Polymer Charging tutorials and stuff like that.

various battery testing battery capacity testing tutorials before. Um, so check those out if you want to, but it's going to have a similar this. this turnergy one should have a very similar discharge characteristic to this because it's also a Lithium Polymer standard 4.2 charging voltage and the safety cutout voltage I Reckon should be about three volts because really, that's where it. You know it just drops off like that, just drops off like a brick wall and you've used up, you know, 95 to 99 of your usable capacity of your battery.

So you really don't want the thing to run under three volts if you want to squeeze an extra percent out. Maybe you could go under that, but you know, no three volts. So we'll set our safety voltage down here to three volts. and uh, yeah, I assume that will do that our sample in time.

Oh I don't know. it goes for an hour. We'll set it. let's disable that.

so it's going to sample once per second. and uh, now all we need to do is set up the discharge current and it looks like it's got a discharge current list over here. and um, this is rather interesting. It looks like in set up like multiple stages, but we really don't need that so can I just delete I Wonder if I can just delete one of those import export note sell? So we want to discharge this thing at one C just to get a baseline of how this thing works.

So um, you know it's got a very low ESR this thing. It's capable of 20c discharge so it'll easily handle uh, 5 amp discharge? No problem at all. And really 5 amps is uh, well above, uh, well, quite significantly above any uh discharge current that's going to be used in, say, my little portable USB power supply. But it'll give us good bass line so it should do that I believe it should as soon as I press Go start down here.

It should start discharging at five amps immediately. Four two hours. but we know it's going to be all over in one. and it should our safety voltage cut out at three volts.

I'm assuming the help doesn't tell me that. But um, you know, based on my experience, that's what this kind of software should do. And um I've mentioned before in that previous my electronic load uh, tutorial I I Am Project Video I Think that you can do this yourself. You don't need a fancy 300 watt program or DC electronic load.

You can design. You can design and build your own load. A lot of people. Very popular project.

Actually a lot of people on the EV blog Forum are designing and building really quite nice do-it-yourself electronic loads and a lot of them are either microcontroller programmable or and or PC programmable supplies. So you can do this yourself. Um, you can do it with a DAC card and a you know and a fat and you know, not much else and then op amp, not much else really. So you don't necessarily need a high-end electronic load like this one to get these sort of discharge characteristic.

uh, curves. You can certainly do it yourself. And I've done it myself before using you know, National instruments, that card or something like that, and a little black box which you know, discharges batteries, or if you know, done it in the manual method. I've designed my own little battery discharge logger over the years and uh, there's many different ways to do it.

But anyway, I'm going to give this a go. So here we go. I'm going to press start and hopefully this thing will jump up to 5 amps and it will start recording and get our discharge curves. So here we go.

Uh time. Yeah. Safety voltage. Three volts.

Here we go. start and I've started. but whoop, Four volts. No, what's going on? So I think I know what? I've done wrong.

Delay: This is a delay. It's actually a delay before it starts doing that. So you want to start that with delay zero like that. Okay, so it was.

It was waiting two hours. So let's actually set that to. you know, seconds. So delay Zero seconds.

It doesn't allow us. It allows us 10 milliseconds minimum. So right? I think now it should. Um, after one second delay, jump to five amps I think that's what it's saying there.

Okay, there we go. And yep, we are Five amps and spot on. Five amps and we're dropping 4.07 4.2 You remember it was at it's instantly dropped down to 4.07 due to the internal ESR and uh, you'll find that we'll continue to drop of course until we get down to three volts which should be our safety cutoff voltage here. and uh, so I could hopefully safely go away, but it's only an hour I'll still be here.

Um, so we'll come back when that is done and we should see. You can start seeing. It's slowly starting to step down there. a little tiny step so we should see our discharge curve look very close to that we're going to Sharp Uh, drop at the start and then you know a reasonably linear slope and then it'll start to curve off, curve off, and then boom should drop off the end there.

Um, yeah, probably this one might be a little bit flatter than that at the end point. I Don't know, we'll find out that's the idea of this test. But anyway, there's our capacity going up our capacity in amp hours. I'm assuming it is because it's voltage and current, so it'd be amp hour capacity so it is working very nicely.

See you in an hour and I lied, it's not an hour yet. Uh, we're at about 1.87 I Couldn't help myself. Had to press record again. Uh, one.

1.87 amp hours at the moment? Uh and uh, where you know we're still at a 3.75 volts here and it looks like a linear drop, but it's Uh, not going to be by the time we get to the end of it. and uh, just in case you're wondering, uh, no, this thing does not get, uh, warm at all because the internal ESR is so low in internal ESR of a battery is what actually causes them to heat up of course. And this one's designed for 20 times this discharge current so you won't even see this thing right. You know, rise in temperature by a degree.

and what do you know? It's uh, almost an hour there. depletion time. it seems to have stopped. and, uh, it's yeah.

we were practically spot on the five amp hours there. So it is essentially exactly as rated right there. and it's uh, jumped back up. Of course, it's jumped back up to 3.16 volts because there's no longer any load.

But that was practically spot on an hour. Go figure. Jeez, they don't lie on their label, do they? now? Whether or not that capacity is the same at 20c I Don't know you'd expected it to be a bit less. but there you go, and we have that characteristic discharge curve with that fall off rapid fall off.

And yeah, if we went down to like two points, it just would have fought. It'll just fall off like a brick wall right there. So at three volt cutoff, we're using uh, you know, uh, 95 plus capacity of the battery, 98, maybe even 99 capacity of the battery So the low ball, low voltage uh, battery detection? Um, in this micro, Supply should be set to around three volts. Um, and it can like automatically switch off the output once it reaches that and stuff like that, there's no buzzer in it to sort of alert you.

but the LCD can certainly pop up low bat, low bat and we can view a report down here. But before I do that I think I'll uh, hit that save curve to file and Bingo! It allows you to save that to a bitmap or nice jpeg or PNG Let's choose PNG don't mind PNG so we can save that. We've got our graph and uh, presumably we can save our data as well because uh, load plot from file safe plot to file. we can dot PLT files.

Well, yeah, whatever. Okay, and uh, presumably we can export. Well, maybe if we go into view report, we can export Excel or txt. Excellent.

Well, we should be able to name txt I Don't see any data in there though, so maybe it's uh. query date? No, not sure what's going on there. Hmm, so that's not a bad little app. It certainly did cut out of the safety voltage of three volts which occurred very rapidly there, and if we left it running after that.

if you were doing this test start manual for example, and even if you're sitting there watching it, but you weren't paying attention because you're too busy, you're soldering something for a couple of minutes. Well, you know. Yeah, battery drops down and you can over discharge your battery and uh, it won't be a happy little camper, that's for sure. So having a safety cut off like this works really well.

Now, the other thing they've got is the X-axis here is actually in capacity. Um, usually I prefer that in time, but we should be able to export the data and do that in time. I Mean sometimes you'll want it in capacity, but others you want time. But our depletion time was 59 minutes and 11 seconds and 4.2 volt start voltage.

and it's uh, almost smack on 5 amp hours capacity with a constant current load that will change like with a voltage like in terms of uh, what hours with a constant wattage low. But there you go. That gives you a good indication that this cell is, uh, certainly not. Uh, well, it's certainly not ripping you off.

Anyway, it does meet its claimed spec, so there you go. That's just a little update on the USB power supply and I will endeavor to spend some more time on it, so hopefully more videos come in soon. Catch you next time! Foreign.