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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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Battery on the ground
On Thu, 20 Mar 2008 08:54:22 -0800, "SteveB"
wrote: I have heard that if you sit a battery on the ground or concrete that it will lose its charge faster. Is this true? Steve There is SOME truth to the belief. The concrete is generally colder than a wood board, causing the battery to cool down unevenly and the acid to stratify over time. The "heavy" acid goes to the bottom. The "light" water goes to the top. This apparently can cause "stratification sulphation" which degrades part of the plates much more quickly than when stored on an insulating board. Can't find the cite right now, but it was explained by a battery expert a few years back. There is a reason MOST battery brackets on cars have a plastic tray instead of mounting the battery directly on steel. It is not as serious a problem with today's plastic cases as it was with the old hard rubber cases, but with a large amount of our plastic products coming from China, and the makeup of some of the plastics being less than certain, I would not bet on it not being a problem in the near future. -- Posted via a free Usenet account from http://www.teranews.com |
#2
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Battery on the ground
On Fri, 21 Mar 2008 01:01:58 GMT, with neither quill nor qualm, Howard
Eisenhauer quickly quoth: On Thu, 20 Mar 2008 13:48:28 -0400, clare at snyder dot ontario dot canada wrote: On Thu, 20 Mar 2008 08:54:22 -0800, "SteveB" wrote: I have heard that if you sit a battery on the ground or concrete that it will lose its charge faster. Is this true? Steve There is SOME truth to the belief. The concrete is generally colder than a wood board, causing the battery to cool down unevenly and the acid to stratify over time. The "heavy" acid goes to the bottom. The "light" water goes to the top. This apparently can cause "stratification sulphation" which degrades part of the plates much more quickly than when stored on an insulating board. Can't find the cite right now, but it was explained by a battery expert a few years back. Nowadays, with Global Warming(kumbaya) and all, it's not a problem. chortle Well, 'cept with Clare and the rest of the Arctic Circle folks. Theres just too much ancedotal evidence to dismiss this as an old wives tale and this is the only explanation I've heard that makes sense. I can see this happening on a floor that's in contact with the ground, if the concrete was at room temperature , i.e. a second or third story floor, then you shouldn't have a problem. That being said I have stored batteries on concrete floors, I just give a kick every now & then to keep the electrolyte mixed up. . I stored the new battery for the welder on the shop floor for 2 years and it was still pretty well charged when I tried it. I'm with Wes since I haven't seen any dead batteries from being stored on the floor. Anecdote that, Howie. I've heard the tale but throughout my 15ish years as a Wrench, I never saw it, and I haven't since, 22 more years. The "electrons leaking through the case" only happens with the plates are coated with balonium. ;. g -- Death is more universal than life; everyone dies but not everyone lives. -- A. Sachs |
#3
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Battery on the ground
On Thu, 20 Mar 2008 13:48:28 -0400 in rec.crafts.metalworking, clare
at snyder dot ontario dot canada wrote, There is SOME truth to the belief. The concrete is generally colder than a wood board, causing the battery to cool down unevenly and the acid to stratify over time. The "heavy" acid goes to the bottom. The "light" water goes to the top. This apparently can cause "stratification sulphation" Right. I was wondering if anybody who knew was going to post. Conditions have to be right for it to occur, which is probably why so many don't understand it. |
#4
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Battery on the ground
Don Foreman fired this volley in
: If I pour some battery acid into a beaker, set the beaker on a cold plate and ensure that it is not physically disturbed, do you assert that the solution will stratify after some period of time such that samples drawn from near the bottom will have higher specific gravity than samples drawn from near the top? Thank you Don. I was having near-irresistable urges to post something similar. Apparently, in acid, Brownian motion ceases. Heavy molecules settle out. G LLoyd |
#5
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Battery on the ground
On Fri, 21 Mar 2008 01:13:50 -0700, David Harmon
wrote: On Thu, 20 Mar 2008 13:48:28 -0400 in rec.crafts.metalworking, clare at snyder dot ontario dot canada wrote, There is SOME truth to the belief. The concrete is generally colder than a wood board, causing the battery to cool down unevenly and the acid to stratify over time. The "heavy" acid goes to the bottom. The "light" water goes to the top. This apparently can cause "stratification sulphation" Right. I was wondering if anybody who knew was going to post. Conditions have to be right for it to occur, which is probably why so many don't understand it. If I pour some battery acid into a beaker, set the beaker on a cold plate and ensure that it is not physically disturbed, do you assert that the solution will stratify after some period of time such that samples drawn from near the bottom will have higher specific gravity than samples drawn from near the top? |
#6
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Battery on the ground
On Fri, 21 Mar 2008 14:55:13 -0600, Don Foreman
wrote: On Fri, 21 Mar 2008 01:13:50 -0700, David Harmon wrote: On Thu, 20 Mar 2008 13:48:28 -0400 in rec.crafts.metalworking, clare at snyder dot ontario dot canada wrote, There is SOME truth to the belief. The concrete is generally colder than a wood board, causing the battery to cool down unevenly and the acid to stratify over time. The "heavy" acid goes to the bottom. The "light" water goes to the top. This apparently can cause "stratification sulphation" Right. I was wondering if anybody who knew was going to post. Conditions have to be right for it to occur, which is probably why so many don't understand it. If I pour some battery acid into a beaker, set the beaker on a cold plate and ensure that it is not physically disturbed, do you assert that the solution will stratify after some period of time such that samples drawn from near the bottom will have higher specific gravity than samples drawn from near the top? Most definitely. -- Posted via a free Usenet account from http://www.teranews.com |
#7
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Battery on the ground
On Fri, 21 Mar 2008 17:38:32 -0400, clare at snyder dot ontario dot
canada wrote: On Fri, 21 Mar 2008 14:55:13 -0600, Don Foreman wrote: On Fri, 21 Mar 2008 01:13:50 -0700, David Harmon wrote: On Thu, 20 Mar 2008 13:48:28 -0400 in rec.crafts.metalworking, clare at snyder dot ontario dot canada wrote, There is SOME truth to the belief. The concrete is generally colder than a wood board, causing the battery to cool down unevenly and the acid to stratify over time. The "heavy" acid goes to the bottom. The "light" water goes to the top. This apparently can cause "stratification sulphation" Right. I was wondering if anybody who knew was going to post. Conditions have to be right for it to occur, which is probably why so many don't understand it. If I pour some battery acid into a beaker, set the beaker on a cold plate and ensure that it is not physically disturbed, do you assert that the solution will stratify after some period of time such that samples drawn from near the bottom will have higher specific gravity than samples drawn from near the top? Most definitely. OK, perhaps I should have said lower pH or higher concentration. Even plain water with a temperature gradient will have higher s.g. where colder, down to 39F anyway. |
#8
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Battery on the ground
On Fri, 21 Mar 2008 14:55:13 -0600 in rec.crafts.metalworking, Don
Foreman wrote, If I pour some battery acid into a beaker, set the beaker on a cold plate and ensure that it is not physically disturbed, do you assert that the solution will stratify after some period of time such that samples drawn from near the bottom will have higher specific gravity than samples drawn from near the top? Why wouldn't the cold acid be a more dense than the warm acid? But actually, the acid will stratify due to gravity without even a temperature gradient if it sits long enough without stirring. Good proposal for an experiment, by the way, but you would have to use a battery not a beaker. Let's see if I can keep the polarities straight. If you put a lead-acid battery on your cold plate and establish a temperature gradient through it, the warmer top will try to generate a higher voltage than the colder bottom and you will have a current flowing within the cell that discharges the battery. The top side reaction depletes the H2SO4, making the density gradient worse. When the temperature equalizes, the current flows the other way and the plates even out enough for the same thing to happen again the next day. Without the internal circulating current, nothing much happens. OK, that is probably pretty badly bollixed up, but you get the idea. It has nothing to do with porous cases or external leakage. No doubt somebody on sci.electrochem.battery can explain it better. |
#9
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Battery on the ground
On Fri, 21 Mar 2008 20:23:13 -0700, David Harmon
wrote: On Fri, 21 Mar 2008 14:55:13 -0600 in rec.crafts.metalworking, Don Foreman wrote, If I pour some battery acid into a beaker, set the beaker on a cold plate and ensure that it is not physically disturbed, do you assert that the solution will stratify after some period of time such that samples drawn from near the bottom will have higher specific gravity than samples drawn from near the top? Why wouldn't the cold acid be a more dense than the warm acid? But actually, the acid will stratify due to gravity without even a temperature gradient if it sits long enough without stirring. Good proposal for an experiment, by the way, but you would have to use a battery not a beaker. Let's see if I can keep the polarities straight. If you put a lead-acid battery on your cold plate and establish a temperature gradient through it, the warmer top will try to generate a higher voltage than the colder bottom and you will have a current flowing within the cell that discharges the battery. The top side reaction depletes the H2SO4, making the density gradient worse. When the temperature equalizes, the current flows the other way and the plates even out enough for the same thing to happen again the next day. Without the internal circulating current, nothing much happens. OK, that is probably pretty badly bollixed up, but you get the idea. It has nothing to do with porous cases or external leakage. No doubt somebody on sci.electrochem.battery can explain it better. This is the only theory that makes any sense to me. Restating what I think you have tried to assert, with slight modification and a bit of embellishment if I may: If there is a vertical temperature gradient then cell voltage at the top must be different from cell voltage at the bottom because cell voltage depends upon temperature as well as electrolyte specific gravity (s.g.). If the cell's EMF is different at top than at bottom then current must circulate within the cell. Example: I may have the signs wrong, but let's say that the cell EMF is 12.20 at the bottom and 12.25 at the top. There's a net loop (vector sum) EMF of 0.05 volts so enough current must circulate to produce .05 volts of IR drop in the plates. (Kirchoff's law) But note that the circulating current at the top is opposite in direction to the current at the bottom, so it has the effect of charging in one region while discharging in the other region. This eventually will result in changing the specific gravities of the electrolytes in these respective regions until the difference in s.g. offsets the difference in temperature so difference in EMF becomes zero and a state of equilibrium is reached. Stratification has thus necessarily occurred due to electrochemical action and in spite of kinetic diffusion. I'm quite sure that kinetic diffusion would prevent battery acid from stratifying in a beaker, but (as you noted) a beaker is not a battery. The net charge of the cell would not have changed except that the charge-discharge process is not 100% reversable and efficient (not to mention IR losses) so there must be some net loss of charge until equilbrium is reached. If the battery is temperature cycled from day to day, then this process could happen periodically. In that case, some charge would be lost with each cycle. I don't know anything about how or if stratification would cause plates to "sulfate" or whatever. That probably depends as much or more on battery construction, age and history as anything else. --- I have not noted self discharge rate in batteries kept on my concrete floor to be any higher than others not on the floor ... but there isn't much temperature gradient between floor and near-floor ambient in my space. I keep air circulating 24/7/365 for other reasons. --- I do not presume to dispute convictions or beliefs of others. This is merely my tediously analytical way of trying to understand things. |
#10
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Battery on the ground
On Fri, 21 Mar 2008 23:51:02 -0600 in rec.crafts.metalworking, Don
Foreman wrote, I don't know anything about how or if stratification would cause plates to "sulfate" or whatever. Remaining in a discharged state for any length of time is what causes the plates to form large hard crystals of lead sulfate, usually irreversibly. |
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