Copper Zinc Tap Water Fuel Cell

[dasimpson]

i would understand low voltage but as much current as possible but not the other way round
from looking at the image you must have over 3 volts and at least 25ma

[b_rads]

@dasimpson
First let me say that I really do enjoy interacting with you and all the people on this forum.  This dialog encourages thought and since you dealing with a true “newbie” here, it is good to sort fact from fiction.  I started these experiments with many preconceived notions to ultimately prove my own thoughts to be in error.  With that said, these are my thoughts on why I responded earlier the way I did.  Any output less than about 2 volts will not light that LED regardless of the amperage unless you put it on a Joule Thief circuit, which I have done.  My objective is to stress these cells as little as possible to facilitate their longevity.  A more destructive electrolyte (drano, KOH) will pump up these cells like a bodybuilder on steroids, but they don’t last very long.  The reason I am disappointed, in the conduit tests I have performed, I get approx. ½ volt for every 4” of conduit exposed to the copper.  With that formula, each cell should have produced about 2 ¼ volts.  But they only produced around 1 volt.  By the way, you are very close on the output, 3 cells configured for max volts produced about 2 ½ volts and approx 20ma while lighting the LED. 
Thanks, Brad S

[dasimpson]

i had a feeling i would be the leds i have used start about 2.5v 20ma
as far as i know the more metal in contact makes more amperage not voltage now if you use carben and zinc i feel you would get higher voltage after all that what batterys are made of

i dont think using thors 2 metals you will get more of a running voltage then about 0.80v if i remeber right

[b_rads]

@dasimpson
The information in your last post is invaluable and totally blows up my linear way of thinking about these cells.  To prove your statement I looked at wikipedia and found this.

“The more electrolyte and electrode material there is in the cell, the greater the capacity of the cell. Thus a small cell has less capacity than a larger cell, given the same chemistry, though they develop the same open-circuit voltage.”

I found this statement to be equally important.
“In practical batteries, internal energy losses, and limited rate of diffusion of ions through the electrolyte, cause the efficiency of a battery to vary at different discharge rates. When discharging at low rate, the battery's energy is delivered more efficiently than at higher discharge rates, but if the rate is too low, it will self-discharge during the long time of operation, again lowering its efficiency.”
Again, so much to learn â€" back to the workbench for more testing â€" lol.

[dasimpson]

yeah the energy loss over time is a pain more so in rechargable batteries.
thats why they best used in something with high power demand rather then something with low power like clocks or remotes
i will give you an example i have a wireless doorbell i was using the rechargables in it but found that most the time the doorbell had stoped working
it wouldent see the month out i then had an idea to add a 2.5v solar panel and diode to it the problem stoped then winter hit so had to rethink so i went and got some cheap alkaline batterys been on for 2 month now and no problems when they run flat ill use them in my tourch so no biggy
now i did see somthing on google that was interesting about a water battery what they had done is use rain water when the unit no longer made power they just emptyed the old water and put new in maybe somthing like this would be good