Voltage vs. Ampage (electrolysis of water)

I want to electrolyze water.  I am currently using a 12V adapter power supply with graphite electrodes.  I want to increase the process.  Which would do it better: more voltage or more ampage?  I suppose more of both is best.  Thanks in advance for answering my question!

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no body electrolyses water for no reason.

if you want to convert something nto another compound, e.g sodium chloride to chlorate, go with voltages below 12v but high currents, as they dissolve the electrodes fast.

if you want to quickly make hydrogen gas, which is what i would suspect you are, use very high voltages like anything between 12v-80v, and bi-carb soda as an electrolyte, and also keep the electrodes spaced together within a centimeter or so, because the more water the electtriciy has to pass through, the more the water resists it, but try to use something like copper at the negative electrode, for best results, use copper sheet, because it doesnt get corroded so long as there is nothing in solution that would do so, like salt.

but what lemonie said was true and should be followed.
voltage or current alone doesnt change how much the water is electrolysed, it just changes how fast the electrodes may errode away.

you need a high wattage, the more volts and amps the better. e.i

10 volts 5 amps is better than
100volts 100ma


but still,

i find that there is more hydrogen liberated at higher voltages.
so i would recomend using 24v at the highest possible current you can get which shoudl be roughly 18amps.

to do this, look for laptop power supplies, i know mine produces 18v at 18 amps roughly +/- 5 amps.

Valos_Cor (author)  oldmanbeefjerky6 years ago
I see. Yes, I want to quickly make hydrogen gas. Wow. That means that 24 V at 1.875 amp(ere)s gives me 45 watts which is better than 48 V at .38 amp(ere)s which would give me only 18.75 watts.
RockeyDA6 months ago

dose this seem like a good ideah (pic)

one of my friends is trying to make hydrogen and i tried to make him a powersupply. i made my own secondary winding replacing the 2 secondaries on a microwave transformer using 8 gauge speaker wire. i made i own high power rectifier out of 8 prepackaged diode bridges from scrap pcb's and a random filter cap from a random TV.

i have 7vDC and im not sure how many amps im packing but i can melt small bolts with it. will this work a damn for splitting watter or should i be trying to up my voltage and drop some amps?


hello,perhaps you can help?

We are in process of designing artificial reefs using steel rebar.

Coral is basically made of calcium carbonate and we need to deposit this on the steel structure through electrolysis.

AC is unsuitable for electrolytic purposes, so far as I understand.

Most places that need artificial reefs have electricity issues of one kind or another so we are going to use solar cells.

Solar cells give off DC current, which is perfect.

What we do not yet understand is how far we can place the solar cells from the actual metal structure while retaining enough power to ensure effective electrolysis. Do we lose effectiveness with increased distance? And how do we calculate that?

Also we want to continue powering the structure after calcium carbonate has been deposited as electricity stimulates and speeds up live coral growth.

Reading this chain it seems that what we are attempting is more complex than we first imagined,especially as sea water seems to have implications for copper terminals and has high resistance.

Can you help us understand what we are dealing with please?

Happy New Year and Thank You in advance.

TeslaBoy5 years ago
Actually you need more volts because Volts bring you amps
According to ohms law I(A)= V/R.

So if R is constant at say 1000 ohms then at 100 volts you'll get .1Amp
But if you are at 10v you'll get .01Amp.

When transformers are stating how many amps they put out these are the max or short out ratings.

So my advice use a rectifier and house current to bring the most amps you can wich is still mabye like 1Amp due to the high resistance of water just be carefull
Rhenu TeslaBoy1 year ago

This is wrong. As voltage decreases current increases. According to P=IV, V=P/I, so if you decrease voltages current(A) increases. This is the concept used in transformers.

iceng TeslaBoy5 years ago
Actually  R is also an inverse function of the electrode area.
As the electrode area increases then R decreases !!

And  R  is also related to distance between electrodes.
As distance decreases  R  also  decreases.

So it's reasonable for an isolated 12 VDC supply can do the job.

And don't forget dissolved gasses in water also have an affect on R.

jaevee iceng1 year ago

hmmm. Right idea, wrong symbolism. There is more than one R. I use r and R or R1,R2,R3. Then Rtotal.

iceng jaevee1 year ago

Hi Hawaii Joe,

Nice to actually hear from you... R is actual real resistance which I easily do in my head or measurement of real-time current is preferred to, school class exercise presentation... I never use dinky "r " rather use R'....

Anyway this is a learning site explained by the above Answers designation...

I don't know what you do in engineering forums, though I suspect you straighten pictures and make sure EEs dot lower case letter i and j....

In the old times, sitting around a table, before the web our forums discussion was component price and the opposite human gender to be politically correct....

TeslaBoy iceng5 years ago
Well even then I'm going to go to a inexpensive power source (120vac) with a full wave rectifier and a resistor to limit excessive current draw I feel that this way you could put enough current into the water with out breaking the bank for a transformer that puts out 10 Amps or so since those can be costly due to the amount of copper and iron needed to make it. And better yet 120 vac is your starting point so why step it down If it's not nessacery.
iceng TeslaBoy5 years ago
You are wizard in electronics and presumably able to avoid being electrocuted.

The reason for incorporating a "costly" isolating transformer is  SAFETY  ! ! !

I have and teach unpredictable grand children that at this time touch everything
they see even if instructed not to..

Then ibles is a community of individuals that never heard of the one hand rule
when working with voltage and enough current to kill, ergo the safety aspect
is far more important then shekels..
That is why...

Besides, in my lab, I have many variable low voltage DC power supplies that
are not killer supplies..

Could be a simple as a extension cord with a diode

Also a 10 amp fuse would be a good idea
JimZ71 year ago

How about an Arc welder?

jaevee1 year ago

this is not a question that can be solved with a simple application of Ohms law.. Far from it. I better get back to my engineering forums where people know actual stuff.

zawy1 year ago

Higher volts will allow more "resistant" compounds like simple water to break apart. Less voltage is needed for salt water. Once a sufficient voltage is reached, more voltage will not speed up the process. You need electrodes with a larger surface area and a higher concentration of the compound if your power supply can give more amps than you are getting out of it. Total amps*time will determine how many "atoms" get the electrons they needed to produce the gases. Water by itself requiring higher voltage will need about the same amps so it will require a lot more watt-hours=volts*amps*hours to get the same amount of gas. Salt water will work good, but the anode (negative side) will have the Chlorine gas (not healthy) and the positive side will be producing the hydrogen gas.

For 1 gram baking soda and 0.7 gram salt: 0.29 liters at negative side of CO2 for baking soda or Cl2 for salt. Also 0.29 liters H2 at cathode (if all of is reacted). This requires 0.66 amps for 1 hour. The end product in the water for baking soda is washing soda which is a lot more alkaline and not safe.

Use a microwave transformer like the DIY spot welders to get high current and low voltage, with a 100 amp diode (or a full rectifier using 4 of them) to convert the AC to DC. So 120V*10amps coming into the transformer (1200 Watts) and 100 amps at 12 Volts on the output should get a lot done, about 100 grams of salt per hour producing 142 liters of H2 gas fo about $0.15*1.2 kWhr = .$0.20 of electricity and $50,000 medical bill for messing up.

ShreeK12 years ago

Can Any one please tell me what is amount of molecules released per volt or watt,
For Example

No. of Molecules /volt

No. of Molecules /watt

No. of Molecules /amp

djsnowman064 years ago
Faraday's laws can be summarized by
m is the mass of the substance liberated at an electrode in grams
Q is the total electric charge passed through the substance in coulombs
F = 96485 C mol−1 is the Faraday constant
M is the molar mass of the substance
z is the valency number of ions of the substance (electrons transferred per ion).

coulombs is directly related to amps. so provided you reach the electrolysis voltage of the solution, the more current the better.
I am also interested in accelerating this process, but i DONT want the O2 and the H2 separated (I want them stored as a gas combination). I am going to get a large Diameter PVC pipe (maybe 200mm), cap one end (the bottom) and on the other end a pvc reducer connected to a hose to gather all gasses. Inside, there are many large stainless steel plates with a hole drilled in the middle of each ( to allow the H2 and O2 to rise. The 1st, 3rd, 5th, 7th, 9th plates will be positively charged, and the 2nd 4th, 6th etc will be negatively charged. the pvc is filled with water and bi-carb soda is added. the intenton of the large stainless plates is to increase the surface area for the reaction (space these plates close together)

Also are there any bi-products from using bi-carb soda or stainless steel??? (cant really afford platinum for obvious reasons

Please comment if you think this would accelerate the process, and add any ideas or concerns you may have.

iceng6 years ago
It was a long time ago in school
where we electrolyzed salt water to make and collect some chlorine Gas.

If you are a sloppy student and some chlorine gas leaked out,
you begin to feel congested and dizzy.
The antidote is a simple sniff of dilute ammonia from the reagent bottles.

My eyes were blurry my nose stuffed and as
I reached for the dilute ammonia bottle thinking
I have a bad case of chlorine gas poisoning, I need to get a big whiff.
BUT I was holding the Concentrated Ammonia reagent bottle.

After I recovered, my nasal passages were clear for a month.

Valos_Cor (author)  iceng6 years ago
I went to a website where someone writes about his experiences with electrolysis to get hydrogen gas. He talks about how using NaCl salt makes the oxygen end smell like an overly enthusiastic sanitarian's pool...That was a bit scary, considering how the guy might've been inhaling pure chlorine thinking it was safe.

Your post answers another one of my questions about what salt water really produced. Thanks!
iceng Valos_Cor6 years ago
Your welcome,
it's always nice to know we saved a life :-)

lemonie iceng6 years ago

The antidote to one poison happened to be another?
(Oh dear)
Theoretically ammonia will mop-up chlorine, but the results are unlikely to be harmless.
Interesting story.

lemonie6 years ago
Either as they are related by V=IR.
But try spooning some bicarbonate of soda / baking-powder/ whatever else not table-salt you can find in the kitchen, into the water.

Adding to this comment, adding baking powder or something similar lets it act as an electrolyte to better conduct the electricity, (Water is a horrible conductor when pure.)

Adding salt, though, will separate it into sodium and chloride, i.e. DANGEROUS!
iceng aelias366 years ago
That's a good question I would have to say more ampage because there is a larger amount of electrons flowing through the water. I have done this before with 20000V the result of this isn't much. If you further want to increase the process speed I would suggest to use cold water for lesser resistance. You could easily do this with batteries however they would get flat after a while.
Sorry, that is Dangerously Wrong advice !!
20000V will ionize air and if it can supply enough current, IT WILL KILL.
Any one can put 20KV into water but it is not electrolysis.
How exactly did you measure this voltage with the probes in the H2O ?
I bet it arced across the surface, if it did not short your HV.
I didn't say use 20000V I said I have used it.
iceng6 years ago
Most power supplies let you change voltage.

To increasing the process raise the voltage and the current ( ampage ) will automatically increase.

You could increase the the surface area of your graphite electrodes too.
Put two electrodes on each side. This could increase current.

Valos_Cor (author)  iceng6 years ago
Thanks for answering. I am confused because I saw a power supply that outputted 48 V and .38 A, and one 24 V with 1.875 A.

I can't find a power supply that lets me change the voltage. Any recommended power sources?

I still would love more input to my question.
Normally, power supply ratings describe the maximum current (in amps) that they can deliver at the rated voltage. If your circuit draws less than that, no problem. If you draw more than that, the voltage drops or you overheat/cook the power supply or it turns off to protect itself (a "crowbar" circuit) or some combination of those.

Electrolysis depends on the rate of current flow. How much current you draw depends on the voltage applied and the resistance of the circuit. You can change the resistance by adjusting the spacing of your electrodes, or you can increase the voltage.

Using different materials for your electrodes might also be worth considering; I'll leave that for you to research.
iceng Valos_Cor6 years ago
You can can change voltage to your water solution by putting resistors in series
with your power supply. If you don't have several watt resistors.
You can use incandescent light bulbs as great power resistors.
Different wattage bulbs have different resistance values and they glow.

-PS check out the third ible down on the right side of this page.