Good morning, all in my shed, i have a 24 volt battery and also a 12 volt uh high power device. It's a cryptocurrency miner. It draws 300 watts at 12, volts, hmm, what's that in current um, it's 300 divided by 12, which is oh 25 amps. Yes, that's quite a lot of amps, and so i'm using this thing, um, which is rated 24 volts in with a range of 15 to 40, and the output is 12 volts, 30 amps and uh yeah.

This thing works fine, it gets quite warm. Unfortunately, i can't see what's inside this, because it's completely potted, but these are around 20 pounds. I think let me just check yeah this one was 19 pounds 99 on ebay. Now i do need more of these because, as i scale the system up, i want to rather than get bigger ones of these, i'm not sure these go much bigger, actually just have multiples of them, because that works, because the cryptocurrency miner actually has multiple hashing cards, Which you could drive independently from multiple power supplies, but because of the price of these, i was looking for alternatives, and i found this which says on it: power supply conversion, device dc, 24 to dc 12 volts output, 30 amps maximum 7.60, or something so.

What's that about five pounds really cheap, but is this up to the job of supplying 30 amps at 12 volts um? The immediate advantage of this is that it looks like it all comes apart, so we can have a look inside see what's inside here. It's actually got some extra wires. It's got: yellow and black um for the high power and then red and black, and there's this rather confusing diagram on here with ack for accessory for the red going in and rem for what remote for the red coming out um. This is all to do with car audio and i don't know much about car audio um, but my first concern with this is the wires.

They do look quite a bit thinner than the wires on this device, which i know can handle at least 25 amps yeah. These are quite a bit thinner, um. I might just go and get a lighter actually because people do say, don't they watch out for copper-coated aluminium. So, let's heat this up aluminium if it gets hot generally just melts and collapses, that's not melting and collapsing so that the insulation there is getting very hot.

So that does look like it's uh, copper, tinned, copper and just for comparison. This is copper coated, aluminium wire. So, let's try this and yeah just falls down goes limp, so yeah you can tell the difference between copper and aluminium. Now, as for the conductor thickness, it's a bit tricky to see because i've soldered the big one into an xt90, but i think you can see there that there is substantial, more wire thickness on the more expensive unit and the wires on the cheap, seven dollar unit Are pretty thin right? There are screws all over this unit, so it should be relatively easy to get it apart.

I think it's uh take out those for this top plate and similarly, these, let's get the top plate out and see. What's inside right, let's lift this lid off. Oh there, it is oh, not a lot in there. Is there? Actually there's really nothing in here.

Is there there's um? Well, this is a five pin device here. I'll get the number off that in a moment there's another device here, which i believe i can't see very well, but it's probably three pins. Oh no. I can't see the bottom yet i'll.

Take the bottom panel off in a moment, and we got a couple of electrolytic capacitors here and a couple more here. These ones are 220 microfarads and the black ones are 100 microfarads. I think everything's at 35, volts uh modest size inductor here, but is that really up to 30 amps and there's also a diode here quite a chunky, looking diode we'll have to have a look at what that is. I think i'll take the bottom off and just have a look at the underside of this pcb.

Rather an old-school srbp pcb here it looks a bit cheap, doesn't it and the final screw is hidden under this quality label? I wonder how much quality there really is in here: oh okay, well reasonably wide traces, but there's no attempt to beef up these traces in any way. There's really nothing! Much in here is there. You know. I think i've made up my mind about this already.

I just don't think this is rated for 30 amps. Looking at these wires, my initial impression was: oh, i think, i'd down rate that to about 15 amps max looking at that inductor looking at this single device here, although there is a device there which might be a diode or something we'll have a look at that, Um, i'm now thinking. I don't think this could manage more than about 10 amps. Quite frankly, in fact, i'm going to undo these screws holding these two devices in and drop the whole board out.

I think right. This is out and well it's even worse than i thought that three pin device over there is a seven eight one. So that's just a linear, 12 volt regulator and it looks to me like ack in runs round here, to the input of that regulator and then ack out. The other red comes off the output of that regulator and two of these electrolytic capacitors, these uh, smaller ones hundred mike, are sitting across the input and output of this 7812 respectively.

So all we have here is a 12 volt linear regulator with the red going into it and the other red coming out of it as an entirely separate circuit. It looks like so all that's left for the switch mode circuit, two tiny resistors here, two modest capacitors 220 mic this diode. Let's have a look at what that is. Oh, well, that's nothing special either! That's a 1n! 5.

8. 2. 2.. I'm just going to look up a 1n5822.

This is a 3 amp schottky diode, so you've got the back end of that, which is the anode. Isn't it on ground, the cathode to the inductor and the inductor out to the yellow output? But it's only rated for three amps, so i've i'm having to downgrade this now from 30 amps to three amps, just based on that diode, a couple of resistors here, presumably to set the i know, voltage the output voltage of the switching regulator. Here, let's have a look at this and just see what horrors await us with this switch mode device right. That's a jrc, 2, 3.

6. 7. 0. 5.

0. 2. 3. 6.

7. 0, 5, 0. I'll. Just look that one up - and this is a 5 amp or possibly 5.5 amp high power dc to dc converter controller ic uh 7.5 to 40 on the input and the output presumably is set by this potential divider of these two resistors, but five amps 3 amp Diode naughty wires: 30 amps, this ain't, so 30 amps.

I think, there's a missing decimal point here: 3.0 amps maximum yeah. This is a piece of trash, isn't it so there we are, if you were hoping to find a cheap 30 amp bucket converter. Well, this is not it. The device here is heat sink, so i mean it might withstand a bit of over current for a while until this whole aluminium, shell gets red hot, but this diode has no heat sinking at all.

So that's going to overheat pretty quickly. I would have thought yeah. This is not good, so it's a piece of junk uh. Well, unless you want a three volt regulator: don't buy it.

Two regulators actually because you've got the uh, the linear regulator and the switch mode regulator. Um. I will put links to the data sheet for the switch mode device and that diode in the description below i'll, even put a link to the ebay listing. So you can see which item not to buy cheerio.