[Zerm]

Yes, that is what you need.  (Also Voltage * Current = Wattage)  Of course, you can afford a smaller power rating if you have a smaller electrolytic cell.  However, by FreeTheBee's thinking, it will probably be very difficult to quantitatively figure how much power you need without experimentation.  I say just get the highest power that you're willing to pay for and go from there.

[Jango]

Yes, that is what you need.  (Also Voltage * Current = Wattage)  Of course, you can afford a smaller power rating if you have a smaller electrolytic cell.  However, by FreeTheBee's thinking, it will probably be very difficult to quantitatively figure how much power you need without experimentation.  I say just get the highest power that you're willing to pay for and go from there.

Great, thank you very much guys.

I may start off with a few lantern batteries first before buying the power supply, just to see how well they work.

[Zerm]

Good luck and let us know how it works please!

[FreeTheBee]

Note that a high voltage will lead to side reactions, such as reduction or oxidation of you're solvent. A high potential will than give you large currents, but if those electrons are used to form hydrogen and not copper or zinc it isn't much use.

I should have used the term current density instead of current in my earlier post. If you looked up the Butler Volmer equation, you might have noticed the A in there. Increasing overpotential leads to a higher current density and thus to a higher current. But, using a larger electrode at the same potential also increases current since the current equals current density times surface area.

That's why I pointed out that it is good to use large electrodes, since then you can maintain high currents at a relatively low current density. This way you don't need as high overpotential, which reduces problems with side reactions.

Good luck with the experiments.

[Jango]

Note that a high voltage will lead to side reactions, such as reduction or oxidation of you're solvent. A high potential will than give you large currents, but if those electrons are used to form hydrogen and not copper or zinc it isn't much use.

I should have used the term current density instead of current in my earlier post. If you looked up the Butler Volmer equation, you might have noticed the A in there. Increasing overpotential leads to a higher current density and thus to a higher current. But, using a larger electrode at the same potential also increases current since the current equals current density times surface area.

That's why I pointed out that it is good to use large electrodes, since then you can maintain high currents at a relatively low current density. This way you don't need as high overpotential, which reduces problems with side reactions.

Good luck with the experiments.

Thanks, I'll bear that in mind and make sure that my electrodes are as big as possible.

I once tried to electrolyse copper sulphate using two 9V batteries, and I got hydrogen at the cathode as well as copper, that explains why! At first I had no idea what was going on.