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PSU not up to electrolyser job?

JulesP

New Member
Hi there,

I’m building an Electrolyser to produce OxyHydrogen gas for brazing and welding (see attached). Part of the plate conditioning process requires putting 12V across the plates and allowing about 5-10A through for prescribed periods. However my modest lab power supply unit (supposed to be able to deliver 30V at 10A) seems unable to put more than 4V across the plates while delivering 9A.

I’m assuming this is a limitation of the PSU and so am contemplating building a beefier one using a power transformer and a rectifier/ smoother.

My question is: is the low voltage across my Electrolyser due to a ‘weak’ power supply or something else?
 

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Diver300

Well-Known Member
Most Helpful Member
The online reviews of that power supply are not good, so the limitation doesn't surprise me.

The mixture of hydrogen and oxygen from electrolysis is extremely explosive. so you would not want to try brazing with it. The oxy-acetylene or oxy-propane welding kits have the fuel and oxygen in separate tanks and are only mixed in the flame.
 

JulesP

New Member
I guess I’ve found its limitation.

HHO implodes not explodes and has been used for decades for welding with unique properties. Welding torches uses the gas straight off an electrolyser. Here is one link:


I could use a car battery as a convenient 12V supply but how might I control the current flow easily rather than let it take what it wants?
 

rjenkinsgb

Well-Known Member
Most Helpful Member
Note that the gear in the video uses two separate gas lines to the torch.
It says in that, that the gasses are only recombined at the very tip of the torch.

No mixed gas is produced so no (or minimal) explosion risk. It's a very different situation to a container full of mixed hydrogen and oxygen which can explode violently.
 

JulesP

New Member
Any thoughts about getting 12V consistently to the Electrolyser? Besides a car battery I could use a power transformer and rectifier and modify the input to the primary with an SCR to control the output current?
 

Diver300

Well-Known Member
Most Helpful Member
Note that the gear in the video uses two separate gas lines to the torch.
It says in that, that the gasses are only recombined at the very tip of the torch.

No mixed gas is produced so no (or minimal) explosion risk. It's a very different situation to a container full of mixed hydrogen and oxygen which can explode violently.
I agree. Water can be electrolysed to hydrogen and oxygen. One will come from the each electrode, and a suitable design of cell can keep them separate.

It's a lot easier to buy the gasses.

You can buy a better power supply for a lot less work than designing a controller.
 

JulesP

New Member
What is it about the PSU I have that makes it unable to deliver 12V to my Electrolyser? Is the total power it can deliver not what it is rated at or is it something to do with the load I am using?
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
Play with plate separation and area of the plates.

As a kid I made H2 and O2 into inverted test tubes. I got a hold of some platinum screen, I think.

Routinely for quartz glass blowing, I used separate tanks of Hydrogen and Oxygen for purity for making crystal growing and synthesis tubes for novel semiconductor material. I combined zinc and phosphorous in an evacuated quartz tube, sealed it under vacuum and heated it slowly over a few days.

Crystal growth prep was a bit weirder. You start with a tube of material and put a controlled hole (leak) and seal that,. Then you place that into a larger tube and seal that under vacuum. Finally, you attach a quartz rod. This is pulled very slowly in a furnace for about a week.

One variation was to use seed material.

The oxy/hydrogen flame is rather clear. That area had a hydrogen alarm that shut the gas cylinders off. In the latest variation, the cylinders were outside.

Oxy propane was available too.

I did use MAPP gas and also acetylene/oxygen when silver soldering.

I've done soldering with Indium through silver. Although not experienced, I did try to stick, MIG and TIG weld. My first welds on steel were fine.
 

JulesP

New Member
All sounds like fun but to condition my plates I need a PSU capable of delivering 12V at 10A max and my eBay one can’t do that.

Im thinking of building what’s on the attached but I’ve been told an ATX supply from an old computer will do that and enable me to control I and V.

If that’s so then I’m looking for a circuit to be able to set it up right.
 

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ClydeCrashKop

Well-Known Member
Most Helpful Member
I played with that once, until I thought better of it. The concentration of electrolyte determined the amperage. For safety reasons, I used baking soda and kept adding more to the water until I got the amperage I wanted. What are you using for electrolyte?
 

JulesP

New Member
I’m using 2M KOH (about 10% w/w) but that’s only for the conditioning stage. Whether I can set the amperage using conductance or not having a PSU with independent control of V and I is a good option.

Have you heard of using an ATX unit from an old PC?
 

alec_t

Well-Known Member
Most Helpful Member
Have you heard of using an ATX unit from an old PC?
Plenty of projects use old ATX supplies. A typical 400W-rated ATX supply would likely give you 15A or so.
 

ClydeCrashKop

Well-Known Member
Most Helpful Member
Have you heard of using an ATX unit from an old PC?
Yes and it works well.
It Needs a load so put a 10 ohm 10W resistor between any +5 red wire and ground.
An alternative is a 12 volt automotive turn signal bulb. It will be a load and glow just bright enough to be a power indicator.

ATX power supply pinout.jpg
 

shortbus=

Well-Known Member
Most Helpful Member
I played with that once, until I thought better of it. The concentration of electrolyte determined the amperage. For safety reasons, I used baking soda and kept adding more to the water until I got the amperage I wanted. What are you using for electrolyte?
That was my understanding of the amperage control too. Many people see this stuff on Youtube and take how some one lucky(so far) has done things. But a mix of oxygen and hydrogen right from the separator is an explosion looking for a place to happen. Especially someone that has no idea what they are doing. Shown very well by his "custom power supply schematic". The only thing to hope for is that he lives alone in an open area when using this, so no innocent is hurt or killed.
 

JulesP

New Member
I found a comprehensive guide as to how to make at ATX based PSU but someone said that it was possible to adjust the amperage down from what the load dictates while keeping the same voltage. Any truth to that?
 

Pommie

Well-Known Member
Most Helpful Member
The load will dictate the amperage unless you vary the voltage. Or the load isn't resistive!

Mike.
 

JulesP

New Member
Sure I assume it’s Ohmic in which case the electrolyte concentration is my only amperage adjustment.

If I use an ATX type supply, will the voltage keep fairly constant at 12V while the current adjusts to the conditions?
 

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