Theoretical efficiency of electrolysis

[Low-Q]

I am curious what is the least amount of voltage and amps necessary to produce hydrogen and oxygen.

You will produce HHO as soon as the voltage is more than 0V. My tapwater have a volt/amp ratio of approx 1/20 - which means 1 ampére for each 20V supplied. At 10V I measure 0.5 amps. I am currently using 36V, and the electric current is now 1.8A. That is about 65W. The generator gets quite hot after an  hour, but it seams it stops heating at about 50 degrees Celsius - which is reached after an hour or so.

The Volt/Ampére ratio depends on the water and the shape and distance of the electrodes. In my case I use stainless steel-wires wound on a plexiglass holder (Bought on ebay).

I have a pair of 1200W class D audio amplifiers which I want to test with square pulses upp to 80V. I can also bridge them to achieve about 160V. That should give about 1200W HHO generator at 8 amps

Vidar

[billmehess]

I put together 4 water batteries using 4ea 32" long 3"  diameter pvc tubes. Each tube had a 3/4 diameter copper rod 32" long and a 3/4 "diameter zink coated rod also 32" in length.  I coated the rod with a dielectric material to prevent the zink coating from being "flacked off" due to the electrolysis effect.
Each tube generates around .8 volts at around 2.5 ma. each. I connected them in series and got 3.2 volts of course still at 2.5 ma.
My electrolyzer is using stainless steel wire with the cathode and anode about 1/2" away from each other.
I am using baking soda in the ectrolyzer with plain tap water. When "turned on" the voltage drops to around 2.56 volts within about 8 hrs but then stablizes at this voltage.
If I change the water about twice a week the process is repeated. I have been running this now for over a month. So 2.56 volts at 2.5 ma will produce H continously. Adding additional copper tube increase the current to increase the H being produced.
The foot print of the 4 tubes is 50 in sq.
Since they are only 32 " tall a like stack above them would generate twice the H with the same foot print.

Obviously this is very scalable.

[mscoffman]

@billmehess;

That water battery has enough power to run a Jt JouleTheif.
It would be interesting to step up the voltage that you are
running to run the electrolyser as pulses. Also you should think
about using standard NaOH - Lye or KOH - Potassium Hydroxide
as the electrolyte. I'd be concerned that carbon in the baking
soda might start to build up after a while and short things out.
Using a manufactured plate electrolyser would not be out of
the question.

I've also done some design thinking about using some available
inexpensive Bernolli pumps and lawn watering timers to drain
and refill the water battery automatically. The water batteries
could be set up to be overfill proof. And the water could be
set up to drain somewhat uphill for a device installed in a
basement. I think all electronic water timers use a battery
or solar cell to keep their electronics running. That would make
sense to support that power from an additional water cell or
two. They probably all use water pressure to activate their
valves.

:MarkSCoffman

[billmehess]

Thank you Mark on your input. The H production is interesting but it has (as is so often the case) lead to something else using the same technology. I took a 1" diameter copper tube about 10" high and placed a 9"  galvanized bolt down it's center. The footprint is very small as the copper tube is in a 1.25" pvc pipe sealed at the bottom. Each one of these produces .75 v. at .35 ma. I have hooked up a matrix of 25 of these 5 x 5 which
produces 3.75 volts at around 2 ma. I have connected this to a very efficient LED what will run and in about an hour drop to 2.55 volts and then continue to drop very slowly.
The light from the LED is sufficient to read by as it produces a light "circle" on a page approx.10" in diameter. The footprint of this unit is only 8x8.Think of it as a battery with 25 water cells inside of it.  I am going to make 3 more of these to be able to light 4 LEDs.
at one time.
20% of the world does not have electricity. This would provide a power source to provide light for 1-2 hours. The footprint for all four is only 256 in sq. or less than 2 sq. feet.
And it only takes water to run it. The galvanized rod I am using has been running now for almost 7 weeks with no sign of degregation at all.

[mscoffman]

@billmehess;

Then, you really need to use JT JouleThief technology. It can cut the power
drain from Leds way down by pulsing the current at relatively high voltage.
Resulting in much better utilization of potential Led brightness without having
to max out DC power drain. Recently Jeanna posted the historical best of the
best Jt circuit. And user Circuitmall also said he had an unpublished hydrogen
electrolyser Jt circuit. By carefully optimizing circuits, mainly the transistor
type and toroid core and number of winding turns one may be surprised at
what could be accomplished. I think having continuous LED lighting for a
week or maybe two is not out of the question.

I like the water battery because one has to start somewhere and having
something that can clean itself out automatically while materially lasting
a long time and not being too threading seems like the way to go. There
should be some sort of plastic cell covers to keep dust and debris out of
the cells fo rhte long haul.

:S:MarkSCoffman