Some quoted info:
"If you are designing a good cell you may as well make it Efficient.
This means Low voltage across the plates.... between 1.24 V and 3.0 V.
Know that 1.24 V will be very slow production and thus require HUGE plate
area for only small gas Production. but it will get COLD as it runs.
At about 1.7 V it starts to very slightly warm when run with Big current
and anything greater than say 3 V will lose lots of energy in heat.
There is a maximum current allowance for efficiency too,
best to be near 0.25 A per 25mm Squared of plate Reacting surface.
( we are talking about one reacting surface - in mine this is 83mm x
365 mm = 30,295 mmSq. 30,295/625 = 48.4 lots of 0.25 A = 12.1 A)
[guessing that he means calculating the surface of one of each pair of equal plates?]
But you can go up to 0.5 A per 25mm Sq for little loss."
My opinions from reading:
* the best efficiencies are found using a high plate count series cell...but they are not simple to make.
* your 2 series / same electrolyte bath cell is probably running at 6V across the plates
* four of the independent spiral cells mentioned above run as a series would have 3 V across the plates...you'd need to adjust the surface area if using 4 in series?
* the most efficient electrolyte is NaOH...not sure how they handle freezing
I've already got too many things going, but if I were to give it a go I'd try maybe 5 tall peanut butter type jars (plastic if possible with plastic lids) using NaOH...4 being spiral cells..1 being a bubbler. I'd carefully calculate the total surface area needed...set these in a wood box. Keep the areas of collected gas to a minimum. I'd keep the amps under 12 or so.
http://en.wikipedia.org/wiki/Sodium_hydroxide
But you don't play games with HHO...not a project for Beevis and Butthead for sure. I might try it sometime in the future.
At least you've actually made one.....