Electrolysis cell good for two litres/min.

[mael]

[SeaMonkey]

[mael]

[mael]

[mael]

[SeaMonkey]

From the standpoint of getting the maximum number of bubbles per unit of electrical power applied to the cell, a 12 Volt power source connected to a single cell represents a very severe impedance mismatch. This mismatch will result in the majority of the electrical power being converted to 'heat' rather than 'gas bubbles.'

To 'brute force' a single cell (my preferred approach) it is far better to have a low voltage source capable of very high current to match the impedance characteristics for maximum gas production.

The synchronous buck converter will enable the adjustable low voltage/high current to attain the best efficiency and also allow 'on the fly' adjustment to increase or decrease gas production to suit immediate requirements. All this with better than 90% conversion efficiency (approaching 98% at full load).

For 'brute force' operation you'll want the plates reasonably thick (minimum 1/16") with as much surface area as the case will permit. Your thought of making electrical connection to several points on the plates edges is a good one and will surely make the cell more efficient. The total number of plates, and total surface area for interleaved plates, is a simple 'rule of thumb.' Calculate surface area at the rate of 100 milliAmperes per square inch of plate. Therefore, if you design your cell to operate at 30 Amperes based on that rule, you'll be able to go as high as 75 Amperes intermittently without overstressing the plates.

75 Amperes at 4 Volts would be approx. 300 Watts. You'll get a goodly amount of gas there.

75 Amperes at 12 Volts would be approx. 900 Watts for nearly the same amount of gas output.

Gas output is directly proportional to current intensity (Amperes).

With the single cell low voltage high current setup you'll want a strong electrolyte solution: at least 20% Na or K hydroxide up to 25%. By making the electrolyte solution strongly ionic it will have the least possible 'resistance' so as to not generate excessive waste heat.

What you've found about softening the pitch with steam or hot water is correct. Drain the electrolyte from the cell first, then when the pitch is softened up you'll be able to lift the plates and the top cover straight up and out of the case. Then you'll be able to remove the plates and sell the lead to a recycler after you've wrapped it in plastic or paper.

These cells are deep cycle and if able to be recovered by desulfation may still have considerable life left in them. Do the plates look badly disintegrated or are they mostly intact?


You'll have great fun with this project of yours Mael!

Download to see what the synchronous buck converter is all about, and bear in mind that a converter for your cell will be far less complex than the circuitry shown with all its 'bells and whistles.'

If you need any help with parts just give a yell!

[SeaMonkey]

Forgot...

Scrounge the junk yards or metal recyclers for good deals on scrap stainless. Even if it looks terrible with rust and surface discoloration, that will all come off with treatment and the underlying stainless will be good as new.

I know you're already very much aware of this, but, it is truly amazing what one is able to acquire in the way of 'raw materials' for projects at very little cost. You're very resourceful in all that you've done!

As for cutting the plates to size, I use my Dremel Tool with the abrasive metal cutting discs. I first mark the plate dimensions on the stainless sheet with a ruler and a sharpie, then I very, very slowly cut into the markings with my Dremel turning the disc at high speed. I've tried to speed the cutting by applying more pressure as the disc is cutting but this only leads to very short disc life and not much progress in the cut. By going very slowly with light pressure you'll be able to cut nearly an entire plate before the disc is so small that it needs changing.

At the rate of an hour or two each day I've cut out as many as 12 plates in a week.

For attaching power leads to the plates I prefer 'spot welding' the connections. It is possible to make a 'spot welder' with a 6 volt battery. some heavy cable and sturdy contact copper or bronze shaped to pointed contact ends, and a heavy external switch to manually 'pulse' the current into the pressure clamped contact point. You'll get lots of ideas on how to do this by searching the web.

[mael]

I am now looking out for some stainless. I must say that 'dumpster-diving' isn't what it used to be, and these days I might very well be forced to negotiate cash for SS at one of the scrap yards.

I think the ensible approach as far as the plate arrangements are concerned is to make all the plates the same size and to use SS threads, and washers with rubber washers wherenecessary.

I can drill holes in SS reasonably well these days. I find any narrow drill which can make a hole and then try a bigger one. I finish the job off with a SS countersinking bit, and if I need a very large hole then I'll torture that last 'bit' until it goes through.

I was wondering about my being lucky enough to find some flashing made of SS which I could cut into two long strips and wind in a spiral. Obviously the SS would be pretty flimsy if it can be bent like that, so if I did it that way I'd have to add quite a few connections along (across) the length. - I suppose I will use whatever I can get my hands on, and it might take some time.

Those 2 V cells are now both on charge (for curiosity's sake). And actually they are capable of chucking out a lot of amps. The plates are as you wondered, which is that they are not in too bad condition - basically intact. There're no bits in the well to speak of. It does seem a waste in a way. The plates are bulging quite a bit, and some of the sponge-lead is oozing out at the sides, but they are useable.

And that reminds me:- The second cell I hooked-up to test-charge last night was empty - I'd emptied the electrolyte at least two years ago. It was very discharged when I emptied it, so I think there's a lot of S there to go back to acid. Well I put water from my dehumidifier in it instead of bought distilled water. I appreciate the stuff I emptied-out of my dehumidifier isn't as free of impurities as something sold in the shops, but is it OK do you think?

[mael]

I wish I could learn about impedance. I've always wanted to know.

* I knew running 12 V into one cell was putting about 10 V too much into it.

I had known that with this electrolysis anything over 1,24 V was going to result in heat. But I wish I could calculate impedance so I can apply it to other devices I use.

* Would I be somewhere near right if I said that charging a car battery with matched impedance would mean the battery is charged as economically as possible, and that using my pulse-chargers, which have a severe impedance mismatch uses all that potential heat-making over-current to stress those sulphate crystals into submission? I mean:- is the impedance mismatch with my pulser a useful application of impedance mismatching?

On a positive note, you have now convinced me to stop pretending I can shove 12 V into one cell.

Now to look at those buck-converters. ....

[SeaMonkey]

The plate structures on those deep cycle batteries are very strong since their design lifetimes often are measured in decades. Since you're not able to see much lost plate material sitting in the bottoms of the cells that would indicate that they're physically in very sound condition. They were probably taken out of service due to sulfation rather than old age.

Yes, the condensation from your dehumidifier is a suitable replacement for distilled water. If it looks pure and clear it will be fine.

You may want to re-consider dismantling those cells for their cases; they may be more useful to you as rejuvenated energy storage devices. I'd venture to guess that a period of time spent pulsing them would surely bring them back to life. And, with the clear case walls, you'll be able to observe dramatic changes in the plate colorations as the desulfating/charging restores the active materials. The positive plates will become nearly black in appearance while the negative plates will become grey. You'll also be able to see whatever bubbling may result during treatment and be able to make 'adjustments' to minimize it.

A lead acid battery in good condition will have an internal resistance of a few millOhms. A heavily sulfated battery will have an internal resistance as high as 2000 Ohms on occasion. Since a sulfated battery/cell is a special case of abnormally high resistance (DC impedance) a high voltage pulse is required to pierce the high resistance barrier in order to initiate sulfation reversal. As the battery begins to recover the high current pulses will produce much less voltage across the battery/cell because the decreasing resistance as it approaches good health will 'load' the pulses greatly.

While the impedance match during desulfation isn't ideal it isn't harmful to the battery unless the battery gets hot or gases excessively.

By the way, I've just 'repaired' one of those Japanese made (Tayama) electric hot water producing units with the little electric motor/water pump in the base and - wow! - they're ingenious little devices! I use it for making steaming hot water for our tea/coffee. It's several years old and a couple of months ago the pump motor stopped working. So, I finally took it apart to investigate and found everything to be in excellent condition with no real problems. Apparently the disconnection of the motor connector from the control board and replacing it was all it needed. Once it was re-assembled and tested it worked just like new again.

I removed the motor/pump unit and tore it apart to investigate the 'magnetic coupling' that you'd mentioned before and was amazed at how effective it was! Those things are really well made.

[mael]

You are right about be getting cold feet about wrecking those cells.

T'is true that the second one I added to the first in series and put on charge had been empty for a couple of years and that this time I only added distilled water, but I can adjust the acid concentration myself. And if I pulse it until there's no more S left to liberate and have the electrolyte correctly diluted then I'll have two large cells for ... something.

The first cell hadn't been drained and after a few days the electrolyte registers around 1200. That's going to be a goer for sure with some pulsing instead of the DC charge it's on now.

* Last night I couldn't relax and sleep because I was thinking about this 2 litre/min unit I want. I have since long ago wondered about using my 1 litre honey jars. I think I might use ten jars with a few plates in each and run it off one of my hefty pulsers or the pulser through a couple of batteries or even straight DC. I've got to get hold of some sturdy material for caps, and I've got a 1cm thick acrylic sheet I cat use for that. I can cut it with a few tools I have at hand and if I go slowly I should cut it more than melt it. I can stick the circles on my drill stand and use it as a lathe so I can taper the disc to fit snugly into the glass jar. One good thing about a thick sheet like that is that I can thread it, and just in case my bubblers don't work then the cap should pop off rather than blow the sides out of the jar. (I'm used to it)

The other idea I had keeping me awake was using wood to make the electrolyser ... yes, "wood." If I had the cash I'd go and buy a commercial electrolyser. No! I'd buy two. I'd use one and take the other one to bits and learn its secrets and try to make it better and build another from ideas generated from examining it. - But I can't do that yet. What I can do though is to make pretty-much exactly the shape i want in wood, and I was wondering about sealing it with the 'paint' that is used on corrugated rooves - asphalt paint.

If I were to make an electrolyser from wood then I'd like to make it so I can plug it directly into the wall with a dimmer switch into a rectifier and a cap bank. That'd be simple, it'd consume little power, shouldn't get hot, and with (say) 50 cells running off whatever DC 100 V AC translates to, I'd likely be getting more gas than I'd usually use, and have lots to spare for perhaps trying to run an engine off.

What do you think?

Yes. The Japanese are certainly good with their engineering. Those water heaters with the pumps lawst a long time. I've got several of those pumps knocking about the place. With Japanese stuff I've found the electronics rarely give out. In those water heaters the seals might leak in the lid after 10 - 20 years, or the plastic used in the casing may crumble. But they can usually be fixed.

Not so the Chinese junk which has made some inroads here. I do not like opening the back of something made in China as it is obviously made by people who don't like their job - probably forced labour at some political prison.

[mael]

Going back on those water heaters I wanted to say that the other problem which might surface with Jap stuff is that the solder connections of parts which get hot might need 'doing again.'

With Jap stuff the first thing I normally do with a dead unit is to check the plug - that's probably 10 % of them fixed. Then go through the unit and check the parts which might get hot and a lot of them might only have a copper track eroded-away or a leg of a component is rattling where the solder used to be. And as you have found, the connection blocks are also a source of failure.

With Chinese stuff it could be anything.

[SeaMonkey]

If stainless is difficult to find, not to worry.

Some of the most efficient electrolyzers built (commercial) use ordinary steel for the Negative plates (Hydrogen liberating).

For the Positive plates Nickel plated steel is used. Nickel plating is needed for the positive plates to enable them to resist oxidation by the liberated Oxygen.

Carbon or Graphite works exceptionally well for either polarity and may also be used in combination with steel plates.

The old style carbon-zinc dry cells are an excellent source for carbon rods.

With a carbon rod as the central positive electrode mounted inside steel tube (such a conduit) which serves as the negative outer electrode; and insulated wire connections made to each then coated with silicone rubber, it is possible to make a 'plate array' of tubular design which works very well indeed.

The wooden box idea will work, but rather than asphalt line the inside with some heavy duty polyethylene such as heavy duty trash bags. The asphalt does work, and has been used in the past, but it isn't near as durable as the plastic lining. Epoxy paint may be another possibility.

For my small-scale experiments to test things I like to use grocery store glass or plastic jars. We've always got a steady supply of those.

Draining the electrolyte from a lead-acid battery is a great way to prepare it for a very long term storage which effectively puts it into a state of 'suspended animation.'

Your thoughts about constructing several low voltage cells in individual containers then series-connecting them to a higher voltage source is, in my experience, the most effective way to go about it.

[mael]

I can see the limitations of a wooden set-up. I doubt it'd last and would need watching.

Those graphite rods - I happen to know where about a thousand of small batteries have been left. I don't know how many of them are alkaline (with smaller rods), but I'm sure I'd find enough for what I want.

How would I connect a wire to a graphite rod?

* thread a SS screw in it?

* Wrap a coil or two of copper around the base and dip it in something tough and waterproof?

* Er ... ?

Graphite rods do seem to have some attractive qualities for an electrolyser and a good one is that they won't get eaten away.

* Sorry about the little typos here 'n there ... I always seem to mumble 'I wish I could edit' after I hit the send button.

[mael]

... Or wrap some sturdy SS wire a turn on each rod?