hodges
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My Homemade Lead-Acid Battery Sucks!
I tried making my own lead-acid battery. I used two thin lead plates from a craft shop with about 50 cm^2 of area in a solution of 6M H2SO4 made from
acid drain opener.
When electricity is forced through such a cell, the anode becomes coated with PbO2 and hydrogen is evolved from the cathode. This results in PbO2/Pb
plates just like in a regular lead-acid cell.
And it did work, to an extent. I got about 2.2 volts out of the cell. I was able to draw a couple of amps of current - but only a few seconds before
the cell died. No matter how much I charged it would not do much better.
Looks like the battery companies don't have to worry about loss of sales to me for a while  .
Hodges
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Geomancer
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I have never done this, and don't wish to (the less lead around me the better), but a quick perusal of the 'net seems to indicate a that you
need to "form" your plates. When your cell evolves hydrogen, that indicates there is no PbSO4 around to electrolyse, once this happens,
discharge the cell completely, preferably at constant current (50 mA or so) and repeat the process. Some sources recomend reversing the polarity
between iterations. Repeat enough times to to build up a layer of stuff on the electrodes, but not enough to destroy the structure.
Modern cells form the plates from a Pb0 paste. Hope this helps.
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Mr. Wizard
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lead acid cells
Your cells don't have any high amperage capacity because they don't have enough lead peroxide and lead to be turned to lead sulfate. You
have to increase the surface area of the plates by either casting a grid which is then packed with the active ingredients or taking a tool such as a
sharp chisel to the plate and cutting thousands of fine grooves in virgin lead sheets. You have to have lots of area and keep the plates close
together in the acid to keep the resistance low. Forming the plates causes the high surface area to form. I have an old book on making these batteries
if you are interested.
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vulture
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PbO2 is NOT a peroxide.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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Mr. Wizard
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PbO2not a peroxide...
Please excuse my ignorance. Peroxide is the common usage name I'm familiar with. Technically it is Lead Dioxide I guess. Vulture, would you
care to elaborate?
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hodges
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I messed around with this a bit more today. I was able to obtain a slight increase in capacity by repeatedly charging/discharging with alternating
polarity. I can now run a 200 mA motor for just over a minute using this cell. But that means its capacity is still measured in ampere-seconds.
Thanks for the offer of the book, Mr. Wizard. This is more of an experiment than a project, though. If I can chemically form the electrodes
that's one thing, but I'm sure I don't have the patience (or tools) to manually cut a bunch of slits in the plates.
In the past, I have found that just about any electrolytic cell acts as a battery to some extent. For example, if I electrolyze a MgSO4 solution
using carbon rods and I disconnect the power and connect an LED across the cell, it lights for 10 or 15 seconds. In fact, the first time I saw this I
was collecting the hydrogen and oxygen in test tubes at the time and thought I had created a fuel cell. This was not the case, though, because I was
unable to get the polarity to reverse by switching the test tubes. So the "fuel" I think was probably MgO that formed on the negative
terminal.
If anyone else ever wants to experiment and needs a lead plate for free let me know. I bought 4 6 inch square plates and have only used half of one
for this experiment.
Hodges
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Mr. Wizard
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Congratulations on the increase in power stored. I did the exact same experiment once, only my lead was from some straps they wrapped around pipes
near where I lived. The pieces were only about 1" by 2". Then I didn't realize it could improve with use. Even cutting scratches on
the lead with a sharp knife will dramatically increase the capacity of the cell. I did the same 'fuel cell' trick with carbon rods , only
with salt water. I think it actually does use the hydrogen and chlorine formed on the rods as fuel.
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Mumbles
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A peroxide bond is O-O. Lead dioxide(or (IV) oxide if you will) does not have this. Lead Dioxide looks somewhat like this(hey, its the best I can do
with ascii):
O=Pb=O
Theres probably some extra free electrons on there due to the d and f subenergy levels, but I really don't feel like looking up that right now.
It's been a long day and my chemistry notes are all the way on the otherside of the house.
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hodges
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| Quote: | Originally posted by Mr. Wizard
I did the same 'fuel cell' trick with carbon rods , only with salt water. I think it actually does use the hydrogen and chlorine formed on
the rods as fuel. |
I thought it was a fuel cell, but there were a few things that didn't make sense. First the voltage was around 2V, which would be too high for
hydrogen and oxygen. It would still work even if I didn't collect the gases in test tubes (I guess some of the gases might be adsorbed by the
carbon rods, but I would think not that much). The final thing that convinced me it was not was switching the test tubes full of gas. If it was
really converting the gases, the polarity should have reversed. It did not. I left it overnight and I was still getting a small current flowing the
original way. I know a fuel cell can be made this way using platinum instead of carbon rods. But I think there is something special about platinum
(catalyst).
I have a small PEM fuel cell, and in general I'm not real impressed with the technology. They only produce about 2/3 of the voltage that was
used to originally decompose the water to hydrogen and oxygen in operation. The output from a single fuel cell is only around 0.6 volts, which is a
very difficult voltage to do anything with (sure you could put several in series, but they are expensive). Storing hydrogen is not going to be
trivial either. It can be compressed, but again that takes energy. I think if one has a source of very cheap electricity available at a given
location it might be practical to store energy as hydrogen, but as far as far as using conventional electricity to generate hydrogen to run a car (for
example) I don't think it will be practical anytime soon.
Hodges
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chloric1
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| Quote: | Originally posted by hodges
I think if one has a source of very cheap electricity available at a given location it might be practical to store energy as hydrogen, but as far as
far as using conventional electricity to generate hydrogen to run a car (for example) I don't think it will be practical anytime soon.
Hodges |
Hey hodges, whats up? Well, I hear what you are saying but if you visit the Patent websites and look for new hydrogen patents, you would find all
sorts of new technologies. From cheaper ways to manufacture borohydrides to porous metal to absorb hydrogen. You see with the energy crisis of
fossil fuels arround the corner the hydrogen technology will be moving at a fevorish pace. Will it perfect itself before global economic catastrophy
strikes? Stay tuned!
[Edited on 12/25/2003 by chloric1]
Fellow molecular manipulator
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Varmint
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Very coarse sandpaper raked across the surface a few times in both X and Y axis will work too.
I had my best results 4 decades ago by low velocity sand-blasting with relatively coarse media. The trick is to find the air pressure/nozzle distance
combination that beats hell out of the surface but doesn't leave the surface contaminated with too much embedded sand/carborundum or whatever your
blasting media happens to be.
DAS
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