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Dry cell - Big is beautiful
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benny Offline
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Post: #1
Dry cell - Big is beautiful
For a first attempt at a dry cell. went for single generator, 7 plate (6 cell), +NNNNN- configuration, (Last of the big spenders, me) and thought, 'Bollox. Go for broke. Think big'.
End plates, 2 plasticy cutting boards from Asda (wallmart), 304 grade SS plates, 6.5 * 9 inches, plate spacing 3mm using rubber mat for gasket.
NaOH electrolyte. Actual single plate area in contact with electrolyte 5 * 7.5 inches each side.

No PWM used (blew the fets due to short cct on wiring on bench and not had time to find and fit replacements as yet)
No plate preparation other than a wipe down prior to fitting.
Bench test results
Voltage ~14.2Vdc, roughly same as my alternator puts out.
Generator running in fully submerged mode, using external header tank cum bubbler.
Electrolyte adjusted to initially draw 12 amp from cold.
Output at 12A, 0.7lpm
Took about 2 hours constant running for generator to get to anything like lukewarm temp with amps increasing to 17A, output increased to ~ 1.2lpm
Produced a fair amount of iron bloom. (No plate conditioning ?)

Drained gen and replaced electrolyte, adjusted electrolyte to draw 8A from cold
Same applied voltage.
At 8A, HHO production ~ 0.6lpm (?)
after about 2 hours, amps = 12.5, HHO production just under 0.9lpm
temperature still low end of lukewarm.
Still a little iron bloom.
Repeated this with replaced electrolyte. Same results, with little or no iron bloom.

Not quite the results I expected. Reduction from 17A to 12.5A only reduced HHO output by 0.3lpm.

Added more NaOH to electrolyte, and current increased to ~ 17A as before. Again HHO only increased to ~ 1.2lpm. Large increase in iron bloom.

Looks like big is the way to go for keeping temperature under control. Note no PWM used. Might not be necessary with this type of cell if temp stays as per. Not sure what the remaining results prove as per HHO production efficiency.

Just a thought, but might be possible to use multiple generators of this type with auto switching on/off of same to gave step increase/decrease of HHO production on demand, as opposed to using variable PWM.
11-21-2008 03:36 PM
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thomasbala Offline
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Post: #2
RE: Dry cell - Big is beautiful
benny Wrote:For a first attempt at a dry cell. went for single generator, 7 plate (6 cell), +NNNNN- configuration, (Last of the big spenders, me) and thought, 'Bollox. Go for broke. Think big'.
End plates, 2 plasticy cutting boards from Asda (wallmart), 304 grade SS plates, 6.5 * 9 inches, plate spacing 3mm using rubber mat for gasket.
NaOH electrolyte. Actual single plate area in contact with electrolyte 5 * 7.5 inches each side.

No PWM used (blew the fets due to short cct on wiring on bench and not had time to find and fit replacements as yet)
No plate preparation other than a wipe down prior to fitting.
Bench test results
Voltage ~14.2Vdc, roughly same as my alternator puts out.
Generator running in fully submerged mode, using external header tank cum bubbler.
Electrolyte adjusted to initially draw 12 amp from cold.
Output at 12A, 0.7lpm
Took about 2 hours constant running for generator to get to anything like lukewarm temp with amps increasing to 17A, output increased to ~ 1.2lpm
Produced a fair amount of iron bloom. (No plate conditioning ?)

Drained gen and replaced electrolyte, adjusted electrolyte to draw 8A from cold
Same applied voltage.
At 8A, HHO production ~ 0.6lpm (?)
after about 2 hours, amps = 12.5, HHO production just under 0.9lpm
temperature still low end of lukewarm.
Still a little iron bloom.
Repeated this with replaced electrolyte. Same results, with little or no iron bloom.

Not quite the results I expected. Reduction from 17A to 12.5A only reduced HHO output by 0.3lpm.

Added more NaOH to electrolyte, and current increased to ~ 17A as before. Again HHO only increased to ~ 1.2lpm. Large increase in iron bloom.

Looks like big is the way to go for keeping temperature under control. Note no PWM used. Might not be necessary with this type of cell if temp stays as per. Not sure what the remaining results prove as per HHO production efficiency.

Just a thought, but might be possible to use multiple generators of this type with auto switching on/off of same to gave step increase/decrease of HHO production on demand, as opposed to using variable PWM.

If you're not using distilled water you will get iron bloom every time. Plate conditioning with 304 SS might have made the iron bloom worse. 316L would have been the better choice but I understand it's not that readily available in the UK. In any event it looks like you did a great job. If NaOH is hard to get in the UK you might want to try straining the iron bloom out of the electrolyte. I've used coffee filters; seem to work just as good as the filter paper you buy at chemical supply shops. Good Luck. These low gas prices won't last. We need to perfect HHO as best we can to beat big oil.
11-21-2008 06:58 PM
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ghahai ghato Offline
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Post: #3
RE: Dry cell - Big is beautiful
COngrats... good job for a first try...
Yes, try to use distilled water or RO water. Higher amps will cause your cell to work overtime and could be the coause of the iron bloom too...
Play around with the amps and adjust for a practical output...

good luck!
11-22-2008 01:09 AM
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benny Offline
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Post: #4
RE: Dry cell - Big is beautiful
ghahai ghato Wrote:COngrats... good job for a first try...
Yes, try to use distilled water or RO water. Higher amps will cause your cell to work overtime and could be the coause of the iron bloom too...
Play around with the amps and adjust for a practical output...

good luck!

Tap water here is relatively pure and is relatively easy to acquire.
Here's some more information/test results(?)

Applied voltage across generator at 14.5V (bit high but for test purposes only)

Average cell voltage 2.4, but varies slightly from cell to cell, due to plate spacing variation, no doubt.
Voltage across one test cell 2.5V

Generator drawing 10A, HHO output ~ 0.6lpm

One cell shorted out manually (screwdriver across edges of 2 adjacent plates)
Test cell voltage immediately increased to 2.85V
amperage draw almost doubled to ~17A
HHO output jumped to just over 1lpm


What surprised me was that a small change in as little as 0.35V difference across each cell could cause current consumption and HHO production to nearly double.

For next test, time permitting, I will short 1 cell and leave generator running for a longish period of time to see what, if any, changes there are with running temperature. and HHO output level changes over time with this effectively 5 cell generator configuration.
From previous run with extra strength electrolyte I would expect extra iron bloom as per previous testing.

316L ss is available in the UK, but usually comes with wooden leg and prosthetic arm.
(costs an arm and a leg to purchase same)
(This post was last modified: 11-22-2008 02:30 AM by benny.)
11-22-2008 02:26 AM
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ghahai ghato Offline
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Post: #5
RE: Dry cell - Big is beautiful
Yup... 316L cost more than twice the 304....
11-23-2008 03:46 AM
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benny Offline
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Post: #6
RE: Dry cell - Big is beautiful
Source of bloom ?

Partially dismantled my gen, described previously, to reduce number of plates from 7 to 6.
+NNNN- config.

Found one side of plates completely covered in ferrous oxide (rust), with other side of plates coated white as per conditioned(?) plates.
Most likely cause of rust ? Using 304 grade SS plates, with highish current, 20A plus, direct connected to power supply, no PWM, etc, coupled with that I had to use a high concentration of NaOH in electrolyte to get to that current level with the 7 plate configuration.

Cleaned up plates, and re-assembled as 6 plate generator, 3mm plate spacing as previously, and adjusted electrolyte level to have gen draw 10 - 12A, direct connected to 14.2V dc power supply.

Generator is now running, still cool, with no apparent bloom being created so far (2 hours running).

Have not as yet verified HHO output level with this setup but looks comparable to previous 7 plate setup at that current level, but Looks like I might be redesigning to make back-to-back 6 plate generators. -NNNN+NNNN-.


To re-iterate, high electrolyte concentration, coupled to high current levels, looks to be one major cause of iron bloom/rust creation/plate corrosion. (At least with 304 grade SS)

Results update.

Same 6 plate setup. 14.5V applied.
electrolyte concentration lowered from previous testing.
Gen still cool to touch after 45 mins.


At 14 amp draw, output HHO ~ 0.86 lpm (2.25 mins for 2l diet coke bottle.)
(This post was last modified: 11-24-2008 09:50 AM by benny.)
11-23-2008 01:03 PM
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