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Convert Lead Acid battery to Alkaline - Page 2 — Parallax Forums

Convert Lead Acid battery to Alkaline

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  • prof_brainoprof_braino Posts: 4,313
    edited 2014-07-03 18:55
    About the lead that came out when I cleaned out the electrolyte: the total amount of dust has got to be less than one of those lead weights we put on fishing lines. We throw those in lakes all the time, then each the fish on that end of the string.

    Is lead sulfide more dangerous or equally dangerous than metallic lead or lead oxide?
  • prof_brainoprof_braino Posts: 4,313
    edited 2014-07-04 08:29
    To follow the instructions, I have to charge and discharge the battery several time to reach full potential, so I can't declare the results as complete until then.

    Overnight, the voltage dropped to 8.5 volts. The 12 volt 10 watt LED on the constant current module light dimly is only draws a few milliamp.

    I connected another 12volt 10watt LED using a Joule Thief boost circuit. This puppy is BRIGHT.

    Battery is 8.5 volts, current is 1.4 amps on the 10 amp scale , but only 68.5 milliamps on the 300 milliamp scale (two currnet option onthe Fluke 77 meter)

    I'm checking every half hour or so. Its very bright and going strong after an hour and a half.
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2014-07-04 09:11
    Read the entry under Safety ===> http://en.wikipedia.org/wiki/Lead(II)_sulfide

    At the end of all this, what is your planned use for the battery?

    The reason I ask is I just replaced a 12VDC gel cell as the old one was 5 years old (on a useful life of about 3 years) and all the technical care and feeding of Lead Acid batteries claims that they should not be stored with no charge.

    I don't know if that applies to Lead Alkaline chemistry as well.

    But I haven't be good about keeping my Lead Acid cells topped up. Now I have a real trickle charger.
  • prof_brainoprof_braino Posts: 4,313
    edited 2014-07-04 11:30
    That is interesting. So now it looks like the lead from a dead battery is somewhat stable, and less toxic than other forms of lead, such as lead oxide. So I guess I DON'T want to cook the dust from the sludge in a fire. (For the folks following along but not reading the links, they specifically say lead sulfide in a fire = more toxic).

    Planned use: I replaced all the kitchen under-cabinet halogen lights (120volt, 30 watt, burn your skin hot; burn out every 3 to 6 months $6 each) with LED 12 volt, 10 watt, just as bright, maybe brighter, slightly warm to the touch, possible indefinite life since I de-rated them 15%, still going strong after acouple years. The LED light run off 12 volts, I was thinking of using a battery system so I could still have the light work when the mains service is down. Lead and sulfuric acid are fine as long as they stay inside the battery, just as mercury is fine as long as it stays inside the flourescent lights. But just as flourescent lights break on occasion, the lead acid batteries tend to need service, and splash electrolyte during service, and I don't want to deal with either.

    The rumour is that lead - alkaline batteries do NOT corrode the lead plates, so the lead might tend to stay in the battery better. Also, the electrolyte, being pickle juice, is not as nastry as sulfuric acid. Also lead alkaline batteries are rumoured to tollerate abuse such as deep discharge, partial recharge, and over charge, with low or no ill effects. The trade off being that they have 1/3 capacitry (best case), and lower max voltage (11.8 volts max) than the original lead acid battery.

    So, I'm NOT going to actually do it in the kitchen, but the experiment is to see if this lead alkaline battery could power a lighting system, such as under cabinet kitchen lights, and continue to function when the mains are down. I would test it for a couple years in the lab before drawing any conclusion. There's nasty stuff down here anyway, and low voltage back lights could be handy.

    The LED modules are rated 12 volts, 1 amp. I would have 5 to 10 lights. Using a Joule Thief boost circuit, the LED is just as bright as the same LED on a constant current module, but only draws 55 to 75 mA. And by bright I mean a blue dot when you look away if you happen to glance directly at it (so I have it behind the volt meter so I don't fry my eyeballs).
  • prof_brainoprof_braino Posts: 4,313
    edited 2014-07-05 08:12
    Yesterday, The test ran with a constant current module until the LED was (subjetively) considered not bright enough, then switched to Joule Thief circuit for the rest of the day.

    The test ran for 14 hours (09:00 am to 23:00) at 8.5 volts 1.5 Amps down to 8.0 volts 0.05 Amps (on the 20 amp scale) and/or 8.1 volts 31.29 milliAmps (on the 300 milliamp scale)

    I don't know why the same Fluke 77/BN meter gives different reading on the current scales. An Mother Tool MT-2070 is the volt meter, and it connection is not touched.

    Today its run about three hours, from 8.2 volts 0.07A / 8.3v 41.6 mA, down to 7.9v 0.04A /8.0V 25.6mA

    Not too bad for a dead battery.

    The LED in not so bright now, but I still don't want to stare at it. I'm going to put it back on the charger and how far it gets before bed time.
  • Dave HeinDave Hein Posts: 6,347
    edited 2014-07-05 08:38
    Not too bad for a dead battery.
    Yes, your previously proud lead-acid battery is living out it's last days as a cheap alkaline 9-volt battery that dribbles out current in the milli-amp range.
  • prof_brainoprof_braino Posts: 4,313
    edited 2014-07-05 11:26
    Nobody said this would enable you to live off the grid. Its just an experiment.

    Some of us like to try wacky things, like, I don't know, interuptless programming, or alternative power options, or down converting light pulses for distance measurement. Sometimes they pan out, sometimes they don't. But we never know until we try to duplicate the claimed results. The experiments that do pan out make make the effort worth while. Its kind of fun too. You should give it a try.

    Of course, its easier to sit back and say "that will never work", and keep repeating yourself even when it does work. It sounds silly to me, but if silly is your idea of fun, then enjoy!
  • Heater.Heater. Posts: 21,230
    edited 2014-07-05 11:41
    Making batteries is fun.
    As a kid I made a cell from a couple of square inches each of copper and zinc plate immersed in tap water.
    Seeing that it produced a volt or so according to my multimeter I hooked it up to a tiny motor I had lying around.
    The motor turned !

    What, we drink that stuff that comes out of the tap ?!

    Sometimes what you learn is not what you expected.
  • Dave HeinDave Hein Posts: 6,347
    edited 2014-07-05 13:35
    A few years ago I helped my son with his science fair project, where he made batteries from various metals and electrolytes. It was very interesting to see the different voltages and currents that they produced. For his live demonstration he powered a digital clock from a battery made from a few lemons with copper wires and zinc-plated nails stuck into them.
  • prof_brainoprof_braino Posts: 4,313
    edited 2014-07-05 14:16
    So here something that might be interesting. I checked the electrolyte with litmus paper. The Alum water was neutral, and did not change the litmus paper color.
    In one cell the paper turned green, indicating mind alkaline.
    In another cell, the paper turn red, indicating hazardous acid.

    So it looks like I might not have rinsed the battery enough. I was trying to create a minimum amount of cruddy water. Since the water didn't react with the baking soda, I assumed the electrolyte was out.

    Or could it be that the charging process reconstituted the sulfuric acid from the lead sulfate?

    I might have to dump the electrolyte and try again.
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