DC DC converter

I have a power supply capable of 30V 5A. I want a much higher current for some electrolysis. I bought this DC DC converter, which should step it up to 25A and 5V.

I connected the positive of the PSU to the positive input on the converter, connected the two outputs of the converter together, and then connected the negative input to the negative PSU.

My PSU has two controls, the voltage limit, and the current limit, it usually goes by the voltage but if the current reaches the limit, the voltage gets stopped and a red 'current' light comes on. Otherwise the green 'voltage' light is on.

When I turned it on, it ticked and flashed between these lights. I checked the voltage across the converter's output quickly and it was about half a volt.

HELP

"...connected the two outputs of the converter together..."

Are you saying that you shorted the output leads together and then applied power?

I connected the positive of the PSU to the positive input on the converter, connected the two outputs of the converter together…

Do you have a link to the wiring diagram? You should NEVER connect two outputs together, but I only see 4 wires. I assume there’s one input and one output, plus an input-ground and an output-ground?

My PSU has two controls, the voltage limit, and the current limit, it usually goes by the voltage but if the current reaches the limit, the voltage gets stopped and a red ‘current’ light comes on. Otherwise the green ‘voltage’ light is on.

The voltage setting should set the fixed/regulated voltage. The current setting should be an (optional) limit and if you exceed the limit the voltage should shut-off or be reduced (“fold back”).

If the DC-DC converter is wired properly and working properly it shouldn’t “pull” any significant current with no load.

I have a power supply capable of 30V 5A. I want a much higher current for some electrolysis.

Since the DC-DC converter does not have current limiting/protection, you’re probably going to need a current limiting resistor.

I’m not a chemist and I don’t know anything about your set-up, but are you sure you can get 25 Amps with 5V? That’s 1/5th of an Ohm…

Draw a picture and post a photo of it showing wire colors and labels.

sounds like you miswired it.

DVDdoug:
Do you have a link to the wiring diagram? You should NEVER connect two outputs together, but I only see 4 wires. I assume there's one input and one output, plus an input-ground and an output-ground?

Yeah, the yellow is output, it has a black output ground next to it. The red is input, and it also has a black ground.

I connected the yellow to the black using a short crocodile clip. And the red and other black I connected to the PSU.

I am also unsure what magic sorcery you need to get 25A from 5V, but many sites on the electrolysis suggested to 'set' such levels.

Little bit of an explanation:
Electrolysis is putting current through a solution. One gets two electrodes and dips them in a solution, without them touching. The charged ions swimming around in the solution kinda act like big electrons and carry charge across. When they get to the terminal, the ions give away some of their own electrons and form new chemicals.
I don't know how to get 5V 25A, but it's called an electrolysis 'cell', so maybe the resistance doesn't really matter because of the ions or something?

So you are connecting the output to ground, shorting it... Why???

To get 25A at 5V you don't need nothing magic, a 0.2 ohm 125W resistor it's all you need!

Ciao, Ale.

pawelzaborek:
I connected the yellow to the black using a short crocodile clip.

Why n Earth would you do that? All that's going to do is test the short circuit protection they claim it to have.

Now, you seem a newbie to electrolysis and I am guessing you think you are going to run your car on Hydrogen thusly generated. Save you money and do some factual research.

The amount of Hydrogen required to run a car would use more electrical energy than it will provide to the car. Unless of course you have discovered perpetual motion to produce the electricity. Even if you have that perpetual motion machine available, the volume of Hydrogen gas required for 1000cc engine running at 5000rpm (do the math of swept-volume and Stoichiometry) would be prodigious. And, require and equally prodigiously sized Hydrogen-gas generation machine in a large trailer dragged behind the car.

I wanted to test it, because it didn’t seem like it could just magically output 5V 25A despite the resistance at output. I didn’t realize that it can’t XD.

So does it just act like a new PSU being powered by my old one, with the maximum 5V 25A instead of 30V 5A??

What is shorting, technically speaking?

SalineSolution:
Why n Earth would you do that? All that's going to do is test the short circuit protection they claim it to have.

Now, you seem a newbie to electrolysis and I am guessing you think you are going to run your car on Hydrogen thusly generated. Save you money and do some factual research.

The amount of Hydrogen required to run a car would use more electrical energy than it will provide to the car. Unless of course you have discovered perpetual motion to produce the electricity. Even if you have that perpetual motion machine available, the volume of Hydrogen gas required for 1000cc engine running at 5000rpm (do the math of swept-volume and Stoichiometry) would be prodigious. And, require and equally prodigiously sized Hydrogen-gas generation machine in a large trailer dragged behind the car.

hahaha, nice explanation :slight_smile:

I want to make sodium perchlorate through electrolysis of sodium chloride. Through a series of reactions, chlorine will form hypochlorate, and three hypochlorates make chlorine and chlorate. Once the level of hypochlorate drops, chlorates react with water to make perchlorate and hydrogen. This process requires a very resistant annode, hence I want to make a carbon substrate lead dioxide annode as I can't afford a platinum electrode...
I wrote the processes out in detail on some practical documents.

A 4-stroke engine would intake 2500 times per minute, so 41.7 times per second. Assuming a mixture of 30% hydrogen to air, 0.3 litres would be needed every stroke. This means 12.5 litres per second. 12.5/24=0.52 mols of H2 per second. If the perpetual motion could produce a high enough current to make hyrdogen at this rate, the size of the water tank trailer wouldn't matter. However it would need to be huge to prevent excessive wear on the electrodes and heating of components. How about store the hydrogen in a pressurized tank?? (It is produced by perpetual motion so the efficiency wouldn't matter)

"What is shorting, technically speaking?"
Shorting is when an electric current takes an undesirable shorter path from and back to the power source, bypassing some or all of the reactive or resistive load which would limit the amount of current flowing. What you did is called a dead short, which, if not limited by the power source, would cause very excessive current to flow. It's like putting a crescent wrench across your car battery terminals. Very hard on the battery and wrench and extremely painful if you are still holding the wrench!

I am having a very hard time understanding how someone so smart could do something so stupid as shorting the output wires. If you don't know what "shorting " is you should not be handling or using electronic circuits until you get a basic understanding of electricity. I wouldn't buy a bunch of chemicals and just start mixing them together. Why would you buy a circuit and start connecting wires together with no idea how to do it correctly ?
It's different if you build a fold-back current limiting regulator and you need to test it, like I did once.
I shorted the output terminals with a beer can opener to test it and there was lot's of sparks but it worked perfectly. If you were deliberately performing such a test you would have stated so in your post , which you did not, so what then is your reason for doing such a crazy thing ?

I’m wondering just how much current could possibly flow through a liquid by applying 5 volts to the electrodes? Well, if it was mercury then yeah, quite a bit. But salt water? The electrodes would have to be “yuge” to require 25 Amps at 5 volts.

I did it because I had the genius thought that it would magically output a set 5V and 25A disregarding V=IR. The first time I turned it off immediately because the ticking PSU scared me. The second time it turned it on for like 3 seconds to read the voltmeter across my short circuit, the crocodile clip just got very slightly warm. So shorting burns components and breaks them?

pawelzaborek:
I did it because I had the genius thought that it would magically output a set 5V and 25A disregarding V=IR. The first time I turned it off immediately because the ticking PSU scared me. The second time it turned it on for like 3 seconds to read the voltmeter across my short circuit, the crocodile clip just got very slightly warm. So shorting burns components and breaks them?

You can't "disregard" the most fundamental Law in Electrical Engineering. Ideal wires have 0 resistance but real life isn't ideal so your wire has some very small resistance. That means that the 0.5V you were measuring was the voltage across the resistance in the alligator clip wire (if you have a good enough ohmmeter, you could measure the resistance of your alligator clip wire and estimate the current you were actually getting). By shorting the output, the power supply just saw a very small "load" and tried to supply enough current to keep its voltage at a constant 5V but because the current required to do that would have been incredibly high, you hit the limit of the supply before it could actually provide what was necessary.

Despite the insults being thrown around, your idea wasn't entirely ridiculous. Shorting the outputs is exactly how you set the current limit on a current controlling power supply. So your bench supply was working as expected but the cheap unit you've bought doesn't have the same sort of protection. So your PSU was actually protecting your converter (and yourself) to some degree.

Ohhhh yeah I see what you mean, thank you very much.

Like the converter was like "oh daayyyyuum, we need 80A for this ouput thing!!, hey PSU give us 400W!!"
The PSU tried but couldn't because I put the limiters on. I'm glad nothing burned or popped.

Despite the insults being thrown around, your idea wasn't entirely ridiculous.

Don't try to "white-wash " it. What he did was worse than ridiculous because he doesn't have a constaant current power source and didn't know that when he did it. What he did was nothing less than playing Russian Roulette with electronic circuits. There is no other way to characterize connecting wires with absolutely no knowledge or experience "to see what happens...". If you think the word "stupid" is unfair,
(I used that word because no effort was made to research the subject before the action was taken) I would have called it "ignorant" if he did not know which wires were which but he clearly knew he was connecting the output wires together when he did it so it was not a "
miswire" per se, which I would describe as "ignorance". It was intentional. Why is this a big deal ?
I have actually seen electronic components explode and scatter high velocity projectiles in all directions. I have seen them catch fire as well but I would be more concerned about getting fragments of a transistor in the eye than a smoking component.

. What would say about someone mixing chemicals with no knowlege "to see what happens.." ?

How would you characterize that ? What words would you use ?

hat means that the 0.5V you were measuring was the voltage across the resistance in the alligator clip wire (if you have a good enough ohmmeter

Where did he say he measured 0.5V ?

Hi,
Are you aware that you will be producing very flammable products of electrolysis.

I worry because so far your history with electricity is not good (I’m not joking…), what are your qualifications?

Tom… :slight_smile: .

TomGeorge:
Hi,
Are you aware that you will be producing very flammable products of electrolysis.

I worry because so far your history with electricity is not good (I'm not joking..), what are your qualifications?

Tom..... :slight_smile: .

Its not flammable, its an oxidizer. I'm a 17 year old doing maths, further maths, physics and chemistry at college.

There is nothing in the world more dangerous than a 17 year old (who doesn't know what they are doing) with access to electronics and chemicals.