Re: [time-nuts] OT Gel Cell question
To clear up the point, lead sulphate is very much more soluble in water than sulphuric acid, and when batteries get flat all the sulphuric acid is reacted leaving only water. That is why no current will flow when trying to charge them. It is all well documented, see: Vinal.G.W. (1945) Storage Batteries, John Wiley Sons, Inc. New York Pp. 464 The sulphate is more soluble at higher temperature, and the daily thermal cycling of an uncharged battery adds to the damage. There are many popular myths and partial truths abroad, largely, I guess, because the study of batteries is in few current engineering courses. Magic additives to restore dead batteries have been around for 100 years, but none of them are effective. The only trick I have seen was an old guy who heated car batteries in an oven, I never found out how long or how hot, he made a living reselling them with a money back six months guarantee. cheers, Neville Michie On 28/07/2014, at 1:59 PM, Chuck Harris wrote: A small disagreement on a couple of points Lead sulfate does not dissolve (in the normal battery chemistry), and does not go all over the place. It forms at the lead and the lead oxide plates, during discharge, and there it stays (unless it breaks off) until you charge the cell. It is the electrolytic cell action that allows the lead sulfate to be converted back into lead metal, lead oxide, and sulfuric acid. Everyone wishes lead sulfate could be dissolved safely, as this could be a way of recovering batteries that have been overly discharged. Lots of snake oil remedies have been created that tout to do just that... things like lime juice, ETDA, adding more sulfuric acid... AFAIK, none of them really work. Shorting in a wet (flooded) lead acid battery happens because the charging/discharging action causes the creation and destruction of lead sulfate, and because the lead sulfate is less dense than the lead and lead oxide it replaces, it flexes the plates. The flexing causes some of the lead sulfate to break free of the plates, and drop to the bottom of the cell. Because energy density is important in a lead acid battery, the manufacturer wastes as little space in the battery case as possible by putting the plates as close to the bottom of the battery jar as it dares. This allows the lead flakes to build up on the bottom until they reach the level of the plates and short them out. The gel cells, and glass mat cells short because the lead dendrites that sometimes grow as a result of charging/discharging, pierce the separator and short the plates directly. -Chuck Harris Neville Michie wrote: Hi, Lead acid cells have lead supports carrying lead oxide and lead metal active material in an electrolyte of sulphuric acid. When they discharge, the sulphuric acid electrolyte is reacted with the oxides and metal to form lead sulphate and the concentration of the acid falls, that is why garages used to check batteries with a hydrometer to measure the electrolyte concentration. At the same time the terminal voltage drops and the internal resistance rises, when the concentration of the electrolyte gets very low, the lead sulphate becomes soluble and will re-deposit all over the battery. With gel cells the electrolyte can be completely absorbed making the battery resistance infinitely high. If you can get some current to flow, you may be lucky enough to get the battery to reform some electrolyte, conduct some more, and eventually charge. However, when flat the lead sulphate dissolves and redeposits all over the battery, and when recharged will convert back to lead and lead oxide, often most inconveniently bridging the plates to a short circuit. The lesson is to not let the battery ever get flat. Lead acid batteries have some very good features. The terminal voltage rises as the concentration of the acid increases. So a constant voltage will charge a cell, and current stops flowing when the electrolyte reaches its proper concentration. The catch is, when you have a battery of several cells, if one cell gets weak, the others will be overcharged causing gassing and over concentration of the electrolyte. There is a judicious voltage that causes an acceptably low rate of gassing (the oxygen hydrogen catalytically recombining) that will keep the charges of cells equalised. But it only takes one total discharge event to cause enough leakage in one cell to bring about failure. Lead acid batteries are also environmentally excellent. They consist of nothing but pure lead and sulphuric acid and water. Sulphuric acid is not volatile so you can make batteries out of old batteries forever, recycling the acid, lead and water. If made on a large scale they are also very efficient (99.9% +) electrically. cheers, Neville Michie ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
Re: [time-nuts] OT Gel Cell question
Back to time related discussions please. Thanks Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
Neville, Sorry, I don't agree. There is plenty of ion exchange capability in the water left over from a totally dead lead acid battery to corrode the skin off of your hands. I have never found one where the specific gravity of the water reached 1.0. Even a couple of drops of acid in the water would be sufficient for significant current to flow. However, it still won't take any charge. Not even a milliamp at 15V. The reason it won't charge is the lead sulfate covering the lead plates is a very good insulator. And, to quote my old college chemistry book: - General Chemistry, 4th Edition, Nebergall, Schmidt and Holtzclaw, DC Heath and Company, 1972. p862: Lead sulfate PbSO4 is formed by ionic combinations, and is insoluble in water but readily dissolved by solutions containing an excess of alkali or acetate ions... I stand by my statements. -Chuck Harris Neville Michie wrote: To clear up the point, lead sulphate is very much more soluble in water than sulphuric acid, and when batteries get flat all the sulphuric acid is reacted leaving only water. That is why no current will flow when trying to charge them. It is all well documented, see: Vinal.G.W. (1945) Storage Batteries, John Wiley Sons, Inc. New York Pp. 464 The sulphate is more soluble at higher temperature, and the daily thermal cycling of an uncharged battery adds to the damage. There are many popular myths and partial truths abroad, largely, I guess, because the study of batteries is in few current engineering courses. Magic additives to restore dead batteries have been around for 100 years, but none of them are effective. The only trick I have seen was an old guy who heated car batteries in an oven, I never found out how long or how hot, he made a living reselling them with a money back six months guarantee. cheers, Neville Michie On 28/07/2014, at 1:59 PM, Chuck Harris wrote: A small disagreement on a couple of points Lead sulfate does not dissolve (in the normal battery chemistry), and does not go all over the place. It forms at the lead and the lead oxide plates, during discharge, and there it stays (unless it breaks off) until you charge the cell. It is the electrolytic cell action that allows the lead sulfate to be converted back into lead metal, lead oxide, and sulfuric acid. Everyone wishes lead sulfate could be dissolved safely, as this could be a way of recovering batteries that have been overly discharged. Lots of snake oil remedies have been created that tout to do just that... things like lime juice, ETDA, adding more sulfuric acid... AFAIK, none of them really work. Shorting in a wet (flooded) lead acid battery happens because the charging/discharging action causes the creation and destruction of lead sulfate, and because the lead sulfate is less dense than the lead and lead oxide it replaces, it flexes the plates. The flexing causes some of the lead sulfate to break free of the plates, and drop to the bottom of the cell. Because energy density is important in a lead acid battery, the manufacturer wastes as little space in the battery case as possible by putting the plates as close to the bottom of the battery jar as it dares. This allows the lead flakes to build up on the bottom until they reach the level of the plates and short them out. The gel cells, and glass mat cells short because the lead dendrites that sometimes grow as a result of charging/discharging, pierce the separator and short the plates directly. -Chuck Harris Neville Michie wrote: Hi, Lead acid cells have lead supports carrying lead oxide and lead metal active material in an electrolyte of sulphuric acid. When they discharge, the sulphuric acid electrolyte is reacted with the oxides and metal to form lead sulphate and the concentration of the acid falls, that is why garages used to check batteries with a hydrometer to measure the electrolyte concentration. At the same time the terminal voltage drops and the internal resistance rises, when the concentration of the electrolyte gets very low, the lead sulphate becomes soluble and will re-deposit all over the battery. With gel cells the electrolyte can be completely absorbed making the battery resistance infinitely high. If you can get some current to flow, you may be lucky enough to get the battery to reform some electrolyte, conduct some more, and eventually charge. However, when flat the lead sulphate dissolves and redeposits all over the battery, and when recharged will convert back to lead and lead oxide, often most inconveniently bridging the plates to a short circuit. The lesson is to not let the battery ever get flat. Lead acid batteries have some very good features. The terminal voltage rises as the concentration of the acid increases. So a constant voltage will charge a cell, and current stops flowing when the electrolyte reaches its proper concentration. The catch is, when you have a battery of several cells, if one cell gets weak, the others will be
Re: [time-nuts] OT Gel Cell question
Ever use batteries to back up your time toys David? I would bet they were lead acid. More that a few folks on this group are using lead acid to run such things. Discussions of charging, discharging, and care of batteries is just as apropos, in my opinion, as discussions on which coax to use, or which receiver to use to run your GPSDO... Or for that matter which SBC to use to run your favorite time hack. It is all part of the infrastructure necessary to make the study of fine time possible. -Chuck Harris David C. Partridge wrote: Back to time related discussions please. Thanks Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
That's for sure. Lead Acid batteries run everything except where power density is critical. We all need to know as much as possible about them. I thought that I knew a lot, but the dialogue on this list has raised my understanding significantly. Thanks to all who have contributed so far. A treasure trove of information. Regards, John K1AE Sent: Monday, July 28, 2014 8:39 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] OT Gel Cell question Ever use batteries to back up your time toys David? I would bet they were lead acid. More that a few folks on this group are using lead acid to run such things. Discussions of charging, discharging, and care of batteries is just as apropos, in my opinion, as discussions on which coax to use, or which receiver to use to run your GPSDO... Or for that matter which SBC to use to run your favorite time hack. It is all part of the infrastructure necessary to make the study of fine time possible. -Chuck Harris David C. Partridge wrote: Back to time related discussions please. Thanks Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
Hi: Using lead acid batteries and a precision frequency standard is not a good thing if they are too close together. A number of decades ago (before the Time Nuts or the internet) I was able to purchase a rack mount Gibbs 5 MHz double oven frequency standard that used a very nice Bliley glass tube crystal because it was not as precise as is was supposed to be. It used GelCell backup batteries that were physically in the same rack chassis as the oven. The fumes from the batteries when charging etched some traces off the PCB inside the oven defeating the temperature control but leaving the oscillator. It took a long time to reverse engineer and repair it. I've added a photo of the cord wood construction of the cylindrical oscillator. The core of the cylinder holds the glass bottle crystal and the glass piston coarse tuning capacitor, surrounded by the first heater, circuitry for the oscillator and dual temperature control circuits on ring shaped boards. These fit inside a cylindrical cavity which is the outer oven. I've added a photo of the inner assembly at: http://prc68.com/I/office_equip.html Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
On 7/28/2014 1:12 AM, David C. Partridge wrote: Back to time related discussions please. Thanks Dave I worked on cesium standards (5071A) at HP/Agilent with Len Cutler of flying clock fame. You better believe that batteries are time related. We jumped through all sorts of hoops to get the 5071A power consumption down to a few dozen watts so it could run off of batteries. The other reason for minimizing power consumption was to avoid fans. HP also used to sell auxiliary battery systems in case the user needed more battery run time than the internal battery was capable of. Rick Karlquist N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
As I understand it, the only time that any sealed lead acid battery will vent is in the case of gross overcharging. The battery is designed so that normal charge rates and correct float voltage will result in recombination of any hydrogen and oxygen produced. Was there a fault in the charging circuit or perhaps, the charging circuit didn't have proper temperature compensation of the charge voltage? Ed On 7/28/2014 10:56 AM, Brooke Clarke wrote: Hi: Using lead acid batteries and a precision frequency standard is not a good thing if they are too close together. A number of decades ago (before the Time Nuts or the internet) I was able to purchase a rack mount Gibbs 5 MHz double oven frequency standard that used a very nice Bliley glass tube crystal because it was not as precise as is was supposed to be. It used GelCell backup batteries that were physically in the same rack chassis as the oven. The fumes from the batteries when charging etched some traces off the PCB inside the oven defeating the temperature control but leaving the oscillator. It took a long time to reverse engineer and repair it. I've added a photo of the cord wood construction of the cylindrical oscillator. The core of the cylinder holds the glass bottle crystal and the glass piston coarse tuning capacitor, surrounded by the first heater, circuitry for the oscillator and dual temperature control circuits on ring shaped boards. These fit inside a cylindrical cavity which is the outer oven. I've added a photo of the inner assembly at: http://prc68.com/I/office_equip.html Have Fun, Brooke Clarke ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
as long as it is not a gals/ceramic seal, there is no way to stop sulfuric acid to get out from the cell, just imagine the dilatation diffrence between plastic and metal... 73 Alex On 7/28/2014 10:12 AM, Ed Palmer wrote: As I understand it, the only time that any sealed lead acid battery will vent is in the case of gross overcharging. The battery is designed so that normal charge rates and correct float voltage will result in recombination of any hydrogen and oxygen produced. Was there a fault in the charging circuit or perhaps, the charging circuit didn't have proper temperature compensation of the charge voltage? Ed On 7/28/2014 10:56 AM, Brooke Clarke wrote: Hi: Using lead acid batteries and a precision frequency standard is not a good thing if they are too close together. A number of decades ago (before the Time Nuts or the internet) I was able to purchase a rack mount Gibbs 5 MHz double oven frequency standard that used a very nice Bliley glass tube crystal because it was not as precise as is was supposed to be. It used GelCell backup batteries that were physically in the same rack chassis as the oven. The fumes from the batteries when charging etched some traces off the PCB inside the oven defeating the temperature control but leaving the oscillator. It took a long time to reverse engineer and repair it. I've added a photo of the cord wood construction of the cylindrical oscillator. The core of the cylinder holds the glass bottle crystal and the glass piston coarse tuning capacitor, surrounded by the first heater, circuitry for the oscillator and dual temperature control circuits on ring shaped boards. These fit inside a cylindrical cavity which is the outer oven. I've added a photo of the inner assembly at: http://prc68.com/I/office_equip.html Have Fun, Brooke Clarke ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
That said, I have never seen a gel cell, or a glass mat lead acid battery leak acid, or emit fumes. I'm not saying it can't happen, just that in all of my battery work, I haven't seen it... [unlike with nicads, where I think something is wrong when I don't see leakage.] The seal is something they take very seriously, and is typically some form of elasomeric plastic/rubber. Even the seal between the plastic case and the faston tabs is flexible. If the battery has a cell that is seriously overcharging, due to a short in another cell, it will out gas hydrogen and oxygen due to the electrolytic breakdown of the water in the electrolyte. Probably better that it do that than to blow up. -Chuck Harris Alexander Pummer wrote: as long as it is not a gals/ceramic seal, there is no way to stop sulfuric acid to get out from the cell, just imagine the dilatation diffrence between plastic and metal... 73 Alex On 7/28/2014 10:12 AM, Ed Palmer wrote: As I understand it, the only time that any sealed lead acid battery will vent is in the case of gross overcharging. The battery is designed so that normal charge rates and correct float voltage will result in recombination of any hydrogen and oxygen produced. Was there a fault in the charging circuit or perhaps, the charging circuit didn't have proper temperature compensation of the charge voltage? Ed ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
I think we crossed some wires here. Pun intended. Brook said the fumes ate away the traces and he is right. On a flooded cell batteries such as he describes the fumes are nasty. Its quite normal on a flooded cell to purposely drive them into overcharge. This is known as equalizing. I have to do that on my 2000 Lbs battery from time to time. On Gel Cells that is a very bad process and you don't do it because they will vent. My only wisdom is this. Stay away from hamfest/flea market batteries. They are almost always bad and nothing really revives them. Pay the money and make sure you get a recent build date. Regards Paul. WB8TSL On Mon, Jul 28, 2014 at 1:44 PM, Alexander Pummer alex...@ieee.org wrote: as long as it is not a gals/ceramic seal, there is no way to stop sulfuric acid to get out from the cell, just imagine the dilatation diffrence between plastic and metal... 73 Alex On 7/28/2014 10:12 AM, Ed Palmer wrote: As I understand it, the only time that any sealed lead acid battery will vent is in the case of gross overcharging. The battery is designed so that normal charge rates and correct float voltage will result in recombination of any hydrogen and oxygen produced. Was there a fault in the charging circuit or perhaps, the charging circuit didn't have proper temperature compensation of the charge voltage? Ed On 7/28/2014 10:56 AM, Brooke Clarke wrote: Hi: Using lead acid batteries and a precision frequency standard is not a good thing if they are too close together. A number of decades ago (before the Time Nuts or the internet) I was able to purchase a rack mount Gibbs 5 MHz double oven frequency standard that used a very nice Bliley glass tube crystal because it was not as precise as is was supposed to be. It used GelCell backup batteries that were physically in the same rack chassis as the oven. The fumes from the batteries when charging etched some traces off the PCB inside the oven defeating the temperature control but leaving the oscillator. It took a long time to reverse engineer and repair it. I've added a photo of the cord wood construction of the cylindrical oscillator. The core of the cylinder holds the glass bottle crystal and the glass piston coarse tuning capacitor, surrounded by the first heater, circuitry for the oscillator and dual temperature control circuits on ring shaped boards. These fit inside a cylindrical cavity which is the outer oven. I've added a photo of the inner assembly at: http://prc68.com/I/office_equip.html Have Fun, Brooke Clarke ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
Hi Ed: I don't know. When I got the unit the batteries had been removed. The power supply consists of two 723 based voltage regulator curcuits the first to drop the line voltage to about 20 V (float charging 3 each 6 V Gell Cells) and the second 723 circuit to take in battery voltage and supply a lower voltage to run the unit. The key problem was the short distance between the batteries and the hot oven. Maybe the oven was also heating the batteries. Something to keep in mind today. Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html Ed Palmer wrote: As I understand it, the only time that any sealed lead acid battery will vent is in the case of gross overcharging. The battery is designed so that normal charge rates and correct float voltage will result in recombination of any hydrogen and oxygen produced. Was there a fault in the charging circuit or perhaps, the charging circuit didn't have proper temperature compensation of the charge voltage? Ed On 7/28/2014 10:56 AM, Brooke Clarke wrote: Hi: Using lead acid batteries and a precision frequency standard is not a good thing if they are too close together. A number of decades ago (before the Time Nuts or the internet) I was able to purchase a rack mount Gibbs 5 MHz double oven frequency standard that used a very nice Bliley glass tube crystal because it was not as precise as is was supposed to be. It used GelCell backup batteries that were physically in the same rack chassis as the oven. The fumes from the batteries when charging etched some traces off the PCB inside the oven defeating the temperature control but leaving the oscillator. It took a long time to reverse engineer and repair it. I've added a photo of the cord wood construction of the cylindrical oscillator. The core of the cylinder holds the glass bottle crystal and the glass piston coarse tuning capacitor, surrounded by the first heater, circuitry for the oscillator and dual temperature control circuits on ring shaped boards. These fit inside a cylindrical cavity which is the outer oven. I've added a photo of the inner assembly at: http://prc68.com/I/office_equip.html Have Fun, Brooke Clarke ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
Clearly under an abused situation I have seen cracked/fractured gel cells as an example. Due to I speculate pretty much the poorest of charge design. This includes powdery stuff, corrosion and metal that has been etched from what at sometime was a liquid. Almost the first thing I check is the batteries on test gear I manage to pickup. Regards Paul WB8TSL On Mon, Jul 28, 2014 at 3:18 PM, Chuck Harris cfhar...@erols.com wrote: That said, I have never seen a gel cell, or a glass mat lead acid battery leak acid, or emit fumes. I'm not saying it can't happen, just that in all of my battery work, I haven't seen it... [unlike with nicads, where I think something is wrong when I don't see leakage.] The seal is something they take very seriously, and is typically some form of elasomeric plastic/rubber. Even the seal between the plastic case and the faston tabs is flexible. If the battery has a cell that is seriously overcharging, due to a short in another cell, it will out gas hydrogen and oxygen due to the electrolytic breakdown of the water in the electrolyte. Probably better that it do that than to blow up. -Chuck Harris Alexander Pummer wrote: as long as it is not a gals/ceramic seal, there is no way to stop sulfuric acid to get out from the cell, just imagine the dilatation diffrence between plastic and metal... 73 Alex On 7/28/2014 10:12 AM, Ed Palmer wrote: As I understand it, the only time that any sealed lead acid battery will vent is in the case of gross overcharging. The battery is designed so that normal charge rates and correct float voltage will result in recombination of any hydrogen and oxygen produced. Was there a fault in the charging circuit or perhaps, the charging circuit didn't have proper temperature compensation of the charge voltage? Ed ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
Hi Charles: It turns out that Made in China does not in and of itself mean inferior. There's a spectrum of quality levels. For example there are some very high end companies in China and during working shifts they turn out products that are very bit as good as any you would find. But there may be an unauthorized night shift that uses the same raw materials and makes a product without any QA. It may or may not be as good as the official product. Products from the reject bin may make their way to the open market. There may be a shadow factory down the road where workers trained at the official factory make products with different materials and no QA. There may be a factory anywhere with untrained workers making a sort of lookalike product. From three feet away I doubt anyone can tell the difference. So in answer to your question, it may be that a battery with the Power Sonic label is a quality battery even if it does have a Made in China sticker. Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html Charles Steinmetz wrote: Paul wrote: Stay away from hamfest/flea market batteries. They are almost always bad and nothing really revives them. Pay the money and make sure you get a recent build date. Also, know that there is a huge range of quality represented by the batteries available on the market. Unfortunately, almost all batteries these days come out of just a few factories in China. These manufacturers are capable of designing and constructing first-quality products, but the batteries that are commonly available in the US are made for brands that ask for the cheapest batteries possible. So you need to find a brand that aims higher and actually does its own quality control. And do not be misled by what has become an almost universal bait-and-switch technique: You find a link that says GENUINE [brand] battery!! and when you follow the link the page says [BRAND] battery prominently at the top but when you scroll down you find in tiny print that the battery for sale is compatible with GENUINE [BRAND] battery or is a GENUINE [BRAND] replacement battery and is actually the cheapest, most awful POS battery made. Panasonic SLAs are by far the best I've used (even the ones made in China), but I haven't found any for sale in the US for a few years now. If anybody knows of a source, please share. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
Paul wrote: Stay away from hamfest/flea market batteries. They are almost always bad and nothing really revives them. Pay the money and make sure you get a recent build date. Also, know that there is a huge range of quality represented by the batteries available on the market. Unfortunately, almost all batteries these days come out of just a few factories in China. These manufacturers are capable of designing and constructing first-quality products, but the batteries that are commonly available in the US are made for brands that ask for the cheapest batteries possible. So you need to find a brand that aims higher and actually does its own quality control. And do not be misled by what has become an almost universal bait-and-switch technique: You find a link that says GENUINE [brand] battery!! and when you follow the link the page says [BRAND] battery prominently at the top but when you scroll down you find in tiny print that the battery for sale is compatible with GENUINE [BRAND] battery or is a GENUINE [BRAND] replacement battery and is actually the cheapest, most awful POS battery made. Panasonic SLAs are by far the best I've used (even the ones made in China), but I haven't found any for sale in the US for a few years now. If anybody knows of a source, please share. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
In my previous work I was developing UPSs: I can confirm that in the last years the quality of the typical gel batteries has declined. What once was 7Ah batteries now are sold as 9Ah ones! And 5-6Ah ones are sold as 7Ah... :( One of the best way to identify the quality of sealed batteries is to weigh them: the heaviest have the highest capacity (and in general are also the best because the producer didn't spare on materials). _ Elio Corbolante. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
Elio Oh man I have seen the amp hour magic also. Thought maybe I was just getting older batteries. We have major home chains in the US that batteries sit around for quite some time as measured by the dust on them. So I was thinking that was the case. Regards Paul. On Mon, Jul 28, 2014 at 6:50 PM, Elio Corbolante elio...@gmail.com wrote: In my previous work I was developing UPSs: I can confirm that in the last years the quality of the typical gel batteries has declined. What once was 7Ah batteries now are sold as 9Ah ones! And 5-6Ah ones are sold as 7Ah... :( One of the best way to identify the quality of sealed batteries is to weigh them: the heaviest have the highest capacity (and in general are also the best because the producer didn't spare on materials). _ Elio Corbolante. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
At the risk of adding fuel to the fire, I'd like to chime in and then will go quiet. Based on my first-hand day-job experience: The consumer UPS units I have seen seem to run the float-voltage on Gel Cells at the very high-end of the cell's spec. The goal appears to be to get the battery back to full terminal voltage and do it fast. That way the next AC mains drop out can utilize the full capacity of the Gel Cells. The long term downside is that the cell would rather float at about a volt less or so and thus the life of the cells are reduced rather sharply. Great for the UPS vendors; they get to sell replacement cells! If one enters the 10kW and up category the game changes and the UPS vendors take much care to use a multi-stage charger system to get bulk charge into the cells, but not to float or top off charge the cells too much. Enter the modern AGM-I and AGM-II cells and it becomes a grey area that I am not well educated about. I asked for hard data from the battery vendors, but the answers were mixed at best. Blunt answer I see is: Do not treat flooded lead acid the same as Gel nor as AGM-I nor AGM-II. And ALWAYS use temp sensors for best performance! My 2 cents in the RF/Telecom World. -Brian, WA1ZMS -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of paul swed Sent: Monday, July 28, 2014 8:17 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] OT Gel Cell question Elio Oh man I have seen the amp hour magic also. Thought maybe I was just getting older batteries. We have major home chains in the US that batteries sit around for quite some time as measured by the dust on them. So I was thinking that was the case. Regards Paul. On Mon, Jul 28, 2014 at 6:50 PM, Elio Corbolante elio...@gmail.com wrote: In my previous work I was developing UPSs: I can confirm that in the last years the quality of the typical gel batteries has declined. What once was 7Ah batteries now are sold as 9Ah ones! And 5-6Ah ones are sold as 7Ah... :( One of the best way to identify the quality of sealed batteries is to weigh them: the heaviest have the highest capacity (and in general are also the best because the producer didn't spare on materials). _ Elio Corbolante. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
Brooke wrote: It turns out that Made in China does not in and of itself mean inferior. I did not say that it did -- please actually read what you are replying to. Here is what I said: These manufacturers are capable of designing and constructing first-quality products, but the batteries that are commonly available in the US are made for brands that ask for the cheapest batteries possible. Brands here means distribution companies (many are US companies, but not all) that order batteries to contracted spec from the OEM and sell them in the US (or wherever) under their own brand. PowerSonic (which you mention by name) is one. Actually, pretty much anyone who markets SLAs in the US is one. But there may be an unauthorized night shift that uses the same raw materials and makes a product without any QA. It may or may not be as good as the official product. Oh, please. OEMs make what buyers order. It's got nothing to do with unauthorized night shifts or shadow factories, it all depends on what the buyer (the brand) orders and is willing to check for when it inspects the received products. When you press an OEM for cheaper and cheaper products, it cuts more and more corners, sometimes including corners that the contract specifies shall NOT be cut (if you push a contractor to pinch every penny, you may get product that does not comply with the contract). This is infamously true of Chinese electronics OEMs, but applies generally to OEMs, including many in the US and EU. it may be that a battery with the Power Sonic label is a quality battery even if it does have a Made in China sticker. PowerSonic batteries are, in fact, some of the better SLA batteries available in the US today (although they are a far cry from the best that can be made). Back in March I wrote this on the volt-nuts list: Also, I strongly advise against using the cheapest batteries you can get. Those will invariably be very low quality batteries, which will fail prematurely. There is a huge difference in quality from good SLAs to poor ones. I have found that PowerSonic SLA batteries give good service in the 732A (about $35 each). There are all-black batteries, sold under the AJC brand and many others, that are unmitigated crap. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
I talked about this earlier today, but my message disappeared along with a second message. Neither made it to the list at all. So out of three messages sent, so far only one made it to the list. Let's see if this one makes it. All UPSs have a problem when trying to figure out what float voltage to use since the correct voltage varies with temperature, amongst other factors. Some UPSs use a low-tech way to avoid the problem. They use a standard current-limited constant-voltage charger, but after float charging the battery for a couple of days they disconnect the charger. Too simple! They then monitor the battery and recharge as necessary. This simple trick can double the life of the battery because it eliminates the continuous overcharging that uses up the very limited amount of water in the cell. Ed On 7/28/2014 7:03 PM, Brian, WA1ZMS wrote: At the risk of adding fuel to the fire, I'd like to chime in and then will go quiet. Based on my first-hand day-job experience: The consumer UPS units I have seen seem to run the float-voltage on Gel Cells at the very high-end of the cell's spec. The goal appears to be to get the battery back to full terminal voltage and do it fast. That way the next AC mains drop out can utilize the full capacity of the Gel Cells. The long term downside is that the cell would rather float at about a volt less or so and thus the life of the cells are reduced rather sharply. Great for the UPS vendors; they get to sell replacement cells! If one enters the 10kW and up category the game changes and the UPS vendors take much care to use a multi-stage charger system to get bulk charge into the cells, but not to float or top off charge the cells too much. Enter the modern AGM-I and AGM-II cells and it becomes a grey area that I am not well educated about. I asked for hard data from the battery vendors, but the answers were mixed at best. Blunt answer I see is: Do not treat flooded lead acid the same as Gel nor as AGM-I nor AGM-II. And ALWAYS use temp sensors for best performance! My 2 cents in the RF/Telecom World. -Brian, WA1ZMS -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of paul swed Sent: Monday, July 28, 2014 8:17 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] OT Gel Cell question Elio Oh man I have seen the amp hour magic also. Thought maybe I was just getting older batteries. We have major home chains in the US that batteries sit around for quite some time as measured by the dust on them. So I was thinking that was the case. Regards Paul. On Mon, Jul 28, 2014 at 6:50 PM, Elio Corbolante elio...@gmail.com wrote: In my previous work I was developing UPSs: I can confirm that in the last years the quality of the typical gel batteries has declined. What once was 7Ah batteries now are sold as 9Ah ones! And 5-6Ah ones are sold as 7Ah... :( One of the best way to identify the quality of sealed batteries is to weigh them: the heaviest have the highest capacity (and in general are also the best because the producer didn't spare on materials). _ Elio Corbolante. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
There are some YouTube videos showing how to rejuvenate. Also you can google it for an explanation. I have wanted to try and rejuvenate some, even bought the necessary ingredients, but never got around to it. Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Robert Roehrig Sent: Sunday, July 27, 2014 12:52 PM To: time-nuts@febo.com Subject: [time-nuts] OT Gel Cell question Anyone know why Gel Cell batteries go HI-Z if discharged below a certain level? Also is there a way to rejuvenate a dead one? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
I think the PbSO4 forms crystals rather then spongy deposits that can re-disolve on the lead plates and reduces the effective surface are of the plate. Lower effective area means higher internal resistance. With any lead acid battery the number of charge/dischage cycles depends on how far you discharge them. You can optimize your system for either low size weight and cost or for greatest number of amp hours removed from the battery over it's lifetime The two goals are in conflict. Almost all the methods people use to fix a LA battery that no longer holds a charge don't work so well. If the battery did not have a long enough service lit it's best to buy a replacement that is rated with more amp hours. Don't buy a gel cell unless yu really do need to use it's ability to operate in all orientations, upside down and such. If it will stay upright a sealed, flooded battery will give better performance. Anyone know why Gel Cell batteries go HI-Z if discharged below a certain level? Also is there a way to rejuvenate a dead one? -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
Basically, it is a matter of thickness, and the quality of an insulator. All lead acid cells work essentially the same: A lead oxide electrode immersed in sulfuric acid converts to lead sulfate when power is drawn from the cell. Lead sulfate is a very good insulator when it gets thick enough. So, as the cell discharges, a lead oxide layer builds on the plates. When the lead sulfate gets thick enough, it insulates the remaining lead oxide from the current flow, and the cell is discharged. When it comes time to recharge the cell, you apply voltage, and if the sulfate layer is still thin enough, current will be drawn, and electrolysis action will commence, and the lead sulfate will be turned back into lead oxide, and sulfuric acid. If you let the dead cell sit around before recharging it, the lead sulfate will have a chance to convert even more of the lead oxide to sulfate, and the layer will grow thicker, and thicker, and become a better and better electrical insulator To the point where the lead plates are completely isolated and no current can pass The cell is ruined. One way you can sometimes resurrect a cell in this ruined condition is to apply a high voltage, with a low current limit to the cell. This will get some current flowing, and will convert, albeit slowly, some sulfate back to lead oxide and sulfuric acid. Such repairs take weeks, or months, to work, and have a great risk of forming current hot spots which will physically destroy the plates. Others say that applying a stream of short, high voltage pulses, to the cell will break down the sulfate's insulation ability, and let the electrolysis action commence. Either method will work, somewhat. And only on a cell that isn't too far gone in the first place... eg. a cell that has only been dead for a week or two. -Chuck Harris Robert Roehrig wrote: Anyone know why Gel Cell batteries go HI-Z if discharged below a certain level? Also is there a way to rejuvenate a dead one? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
Hi Robert: I've spent a lot of time charging batteries using different methods and on various chemistries. When the charge is in the form of a pulse, ideally including a reverse polarity pulse, the charge is more effective. This is also a way to sometimes, but not always, will recover a battery that otherwise will not take a charge from a DC source. I think this works because it takes some time for chemical reactions to work and by using a pulse you can force the reaction to a higher level that you can't do using DC without causing problems such as boiling the electrolyte. For more info see Burp Charging: http://www.prc68.com/I/BatChg.shtml#Burp Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html Robert Roehrig wrote: Anyone know why Gel Cell batteries go HI-Z if discharged below a certain level? Also is there a way to rejuvenate a dead one? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
There are some other failure modes for gel cell (and other lead acid types) batteries. One is a shorted cell caused be the plates warping and breaching the separator insulation. This is not recoverable. Another more likely failure is corrosion of the connections to the plates. Also not recoverable. If the battery is more than five years old it is most likely time to trade it in for a new one. Regards, Tom - Original Message - From: Charles Steinmetz csteinm...@yandex.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, July 27, 2014 3:41 PM Subject: Re: [time-nuts] OT Gel Cell question Robert wrote: Anyone know why Gel Cell batteries go HI-Z if discharged below a certain level? Also is there a way to rejuvenate a dead one? As others have explained, the problem is sulfation. I have had good results de-sulfating lead-acid batteries of all types (flooded, gel, AGM) with BatteryMINDer brand chargers/desulfators. With badly sulfated batteries, rejuvination can take a long time. Often, they return to a good approximation of like new performance. Sometimes they improve but don't return to like new. http://www.batteryminders.com/batteryminder-model-1500-12volt-1-5-amp-maintenance-charger-desulfator/ Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
Robert wrote: Anyone know why Gel Cell batteries go HI-Z if discharged below a certain level? Also is there a way to rejuvenate a dead one? As others have explained, the problem is sulfation. I have had good results de-sulfating lead-acid batteries of all types (flooded, gel, AGM) with BatteryMINDer brand chargers/desulfators. With badly sulfated batteries, rejuvination can take a long time. Often, they return to a good approximation of like new performance. Sometimes they improve but don't return to like new. http://www.batteryminders.com/batteryminder-model-1500-12volt-1-5-amp-maintenance-charger-desulfator/ Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
At 04:09 PM 7/27/2014, Tom Miller wrote: If the battery is more than five years old it is most likely time to trade it in for a new one. I have used uninterruptable power supplies and standby power supplies for decades at work to keep mission-critical hardware online. I concur fully with Tom - depending upon the equipment they are used in and the quality of the original cells I replace gel cells every three to five years. It is much better to replace cells at a time of my choosing than to try to stretch their use and have them fail when needed. Dale H. Cook, Contract Engineer, Roanoke/Lynchburg, VA http://plymouthcolony.net/starcityeng/index.html ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
I too have spent a lot of time charging batteries using different methods on various chemistries. Once upon a time, I build a number of suitcase battery chargers for the US Army that allowed them to charge every portable secondary battery type that they had in inventory... SLA, AgO, NiCD, NIMH, LiIon... I proved a concept, and someone else got to make all of the money off of it when the ARMY shopped my prototypes around... but I digress. When you try to charge a sulfated lead acid cell, you can think of the cell as being a bunch of little parallel lead acid microcells (uCell). Each is in some state of charge/discharge. So imagine this: +--+--+--+--+--+--+.+--+---Plus terminal S..S..S.[B].S..S..S.S..S +--+--+--+--+--+--+.+--+---Minus terminal In this case, all of the Ss represent a microcell (uCell) that is highly sulfated, and the [B] represents a microcell that is in perfect condition, and is taking a charge normally. If you try to put current into this lead acid cell, the sulfated uCells will appear as open circuits (due to the sulfate's insulating properties), and the good uCell will take all of the current, and will keep the voltage down to a low enough value that the sulfated uCells will not see any significant electrolysis action. So you say, Pooh, I want the sulfated uCells to charge too! and up the voltage across the lead acid cell, and poof! The good uCell dies from over heating, revealing a new uCell that wants to charge, and poof, it dies, revealing another uCell that wants to take a charge, and poof... You get into a situation where your success causes your failure. If, instead, you apply high voltage pulses to the lead acid cell, you can sometimes beat the system. The good uCells will take a hit, but it is short enough that they don't have time to burn up, and the sulfated uCells will get to draw enough current during the pulse that a little electrolysis will happen, and convert some of their sulfate back into oxide and acid... Sometimes you can win by using a pulse charge system. However, there is a little physical problem that has to be understood. Part of the way the lead acid batteries get their high current handling densities is because the lead plates are made to have high surface area. They are kind of like sponges on the surface. And, lead sulfate takes up significantly more room than lead oxide. Sorry, that is the way it just is. So, when a cell gets all sulfated up, the lead sulfate that forms in the deep nooks in the mossy lead electrodes fills the nook up so full that it breaks it apart, and damages the cell plate. This happens, albeit slowly, even when you treat the battery nicely. You can't win. Long term everything heads towards entropy. -Chuck Harris Brooke Clarke wrote: Hi Robert: I've spent a lot of time charging batteries using different methods and on various chemistries. When the charge is in the form of a pulse, ideally including a reverse polarity pulse, the charge is more effective. This is also a way to sometimes, but not always, will recover a battery that otherwise will not take a charge from a DC source. I think this works because it takes some time for chemical reactions to work and by using a pulse you can force the reaction to a higher level that you can't do using DC without causing problems such as boiling the electrolyte. For more info see Burp Charging: http://www.prc68.com/I/BatChg.shtml#Burp Have Fun, Brooke Clarke ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
it is not a high performance battery but extremely robust, see there http://www.nickel-iron-battery.com/ it is no polluting, it could be shorted out overcharged if you are lucky and find one old forklift with Edison Battery -- which was built some fifty years egoit will out last you too you could charge in current mode, C/10, 2C nothing will happen just replace evaporated water in the elctrtrolyt which is KOH 73 Alex On 7/27/2014 2:41 PM, Chuck Harris wrote: I too have spent a lot of time charging batteries using different methods on various chemistries. Once upon a time, I build a number of suitcase battery chargers for the US Army that allowed them to charge every portable secondary battery type that they had in inventory... SLA, AgO, NiCD, NIMH, LiIon... I proved a concept, and someone else got to make all of the money off of it when the ARMY shopped my prototypes around... but I digress. When you try to charge a sulfated lead acid cell, you can think of the cell as being a bunch of little parallel lead acid microcells (uCell). Each is in some state of charge/discharge. So imagine this: +--+--+--+--+--+--+.+--+---Plus terminal S..S..S.[B].S..S..S.S..S +--+--+--+--+--+--+.+--+---Minus terminal In this case, all of the Ss represent a microcell (uCell) that is highly sulfated, and the [B] represents a microcell that is in perfect condition, and is taking a charge normally. If you try to put current into this lead acid cell, the sulfated uCells will appear as open circuits (due to the sulfate's insulating properties), and the good uCell will take all of the current, and will keep the voltage down to a low enough value that the sulfated uCells will not see any significant electrolysis action. So you say, Pooh, I want the sulfated uCells to charge too! and up the voltage across the lead acid cell, and poof! The good uCell dies from over heating, revealing a new uCell that wants to charge, and poof, it dies, revealing another uCell that wants to take a charge, and poof... You get into a situation where your success causes your failure. If, instead, you apply high voltage pulses to the lead acid cell, you can sometimes beat the system. The good uCells will take a hit, but it is short enough that they don't have time to burn up, and the sulfated uCells will get to draw enough current during the pulse that a little electrolysis will happen, and convert some of their sulfate back into oxide and acid... Sometimes you can win by using a pulse charge system. However, there is a little physical problem that has to be understood. Part of the way the lead acid batteries get their high current handling densities is because the lead plates are made to have high surface area. They are kind of like sponges on the surface. And, lead sulfate takes up significantly more room than lead oxide. Sorry, that is the way it just is. So, when a cell gets all sulfated up, the lead sulfate that forms in the deep nooks in the mossy lead electrodes fills the nook up so full that it breaks it apart, and damages the cell plate. This happens, albeit slowly, even when you treat the battery nicely. You can't win. Long term everything heads towards entropy. -Chuck Harris Brooke Clarke wrote: Hi Robert: I've spent a lot of time charging batteries using different methods and on various chemistries. When the charge is in the form of a pulse, ideally including a reverse polarity pulse, the charge is more effective. This is also a way to sometimes, but not always, will recover a battery that otherwise will not take a charge from a DC source. I think this works because it takes some time for chemical reactions to work and by using a pulse you can force the reaction to a higher level that you can't do using DC without causing problems such as boiling the electrolyte. For more info see Burp Charging: http://www.prc68.com/I/BatChg.shtml#Burp Have Fun, Brooke Clarke ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
Hi, Lead acid cells have lead supports carrying lead oxide and lead metal active material in an electrolyte of sulphuric acid. When they discharge, the sulphuric acid electrolyte is reacted with the oxides and metal to form lead sulphate and the concentration of the acid falls, that is why garages used to check batteries with a hydrometer to measure the electrolyte concentration. At the same time the terminal voltage drops and the internal resistance rises, when the concentration of the electrolyte gets very low, the lead sulphate becomes soluble and will re-deposit all over the battery. With gel cells the electrolyte can be completely absorbed making the battery resistance infinitely high. If you can get some current to flow, you may be lucky enough to get the battery to reform some electrolyte, conduct some more, and eventually charge. However, when flat the lead sulphate dissolves and redeposits all over the battery, and when recharged will convert back to lead and lead oxide, often most inconveniently bridging the plates to a short circuit. The lesson is to not let the battery ever get flat. Lead acid batteries have some very good features. The terminal voltage rises as the concentration of the acid increases. So a constant voltage will charge a cell, and current stops flowing when the electrolyte reaches its proper concentration. The catch is, when you have a battery of several cells, if one cell gets weak, the others will be overcharged causing gassing and over concentration of the electrolyte. There is a judicious voltage that causes an acceptably low rate of gassing (the oxygen hydrogen catalytically recombining) that will keep the charges of cells equalised. But it only takes one total discharge event to cause enough leakage in one cell to bring about failure. Lead acid batteries are also environmentally excellent. They consist of nothing but pure lead and sulphuric acid and water. Sulphuric acid is not volatile so you can make batteries out of old batteries forever, recycling the acid, lead and water. If made on a large scale they are also very efficient (99.9% +) electrically. cheers, Neville Michie ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Gel Cell question
A minor nit The self-discharge rate is pretty high (20 to 40% per month) and the charging is not as efficient. Power density is pretty bad too. For forklift operation this is not a problem as weight is a good thing, they are topped off every night and the power used to run a forklift is minimal given the overall consumption of an average factory. Wikipedia has a nice comparison http://en.wikipedia.org/wiki/Nickel%E2%80%93iron_battery http://en.wikipedia.org/wiki/Lead%E2%80%93acid_battery Here is a vendor: http://ironedison.com/ Dave -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Alex Pummer Sent: Sunday, July 27, 2014 15:48 To: time-nuts@febo.com Subject: Re: [time-nuts] OT Gel Cell question it is not a high performance battery but extremely robust, see there http://www.nickel-iron-battery.com/ it is no polluting, it could be shorted out overcharged if you are lucky and find one old forklift with Edison Battery -- which was built some fifty years egoit will out last you too you could charge in current mode, C/10, 2C nothing will happen just replace evaporated water in the elctrtrolyt which is KOH 73 Alex On 7/27/2014 2:41 PM, Chuck Harris wrote: I too have spent a lot of time charging batteries using different methods on various chemistries. Once upon a time, I build a number of suitcase battery chargers for the US Army that allowed them to charge every portable secondary battery type that they had in inventory... SLA, AgO, NiCD, NIMH, LiIon... I proved a concept, and someone else got to make all of the money off of it when the ARMY shopped my prototypes around... but I digress. When you try to charge a sulfated lead acid cell, you can think of the cell as being a bunch of little parallel lead acid microcells (uCell). Each is in some state of charge/discharge. So imagine this: +--+--+--+--+--+--+.+--+---Plus terminal S..S..S.[B].S..S..S.S..S +--+--+--+--+--+--+.+--+---Minus terminal In this case, all of the Ss represent a microcell (uCell) that is highly sulfated, and the [B] represents a microcell that is in perfect condition, and is taking a charge normally. If you try to put current into this lead acid cell, the sulfated uCells will appear as open circuits (due to the sulfate's insulating properties), and the good uCell will take all of the current, and will keep the voltage down to a low enough value that the sulfated uCells will not see any significant electrolysis action. So you say, Pooh, I want the sulfated uCells to charge too! and up the voltage across the lead acid cell, and poof! The good uCell dies from over heating, revealing a new uCell that wants to charge, and poof, it dies, revealing another uCell that wants to take a charge, and poof... You get into a situation where your success causes your failure. If, instead, you apply high voltage pulses to the lead acid cell, you can sometimes beat the system. The good uCells will take a hit, but it is short enough that they don't have time to burn up, and the sulfated uCells will get to draw enough current during the pulse that a little electrolysis will happen, and convert some of their sulfate back into oxide and acid... Sometimes you can win by using a pulse charge system. However, there is a little physical problem that has to be understood. Part of the way the lead acid batteries get their high current handling densities is because the lead plates are made to have high surface area. They are kind of like sponges on the surface. And, lead sulfate takes up significantly more room than lead oxide. Sorry, that is the way it just is. So, when a cell gets all sulfated up, the lead sulfate that forms in the deep nooks in the mossy lead electrodes fills the nook up so full that it breaks it apart, and damages the cell plate. This happens, albeit slowly, even when you treat the battery nicely. You can't win. Long term everything heads towards entropy. -Chuck Harris Brooke Clarke wrote: Hi Robert: I've spent a lot of time charging batteries using different methods and on various chemistries. When the charge is in the form of a pulse, ideally including a reverse polarity pulse, the charge is more effective. This is also a way to sometimes, but not always, will recover a battery that otherwise will not take a charge from a DC source. I think this works because it takes some time for chemical reactions to work and by using a pulse you can force the reaction to a higher level that you can't do using DC without causing problems such as boiling the electrolyte. For more info see Burp Charging: http://www.prc68.com/I/BatChg.shtml#Burp Have Fun, Brooke Clarke
Re: [time-nuts] OT Gel Cell question
A small disagreement on a couple of points Lead sulfate does not dissolve (in the normal battery chemistry), and does not go all over the place. It forms at the lead and the lead oxide plates, during discharge, and there it stays (unless it breaks off) until you charge the cell. It is the electrolytic cell action that allows the lead sulfate to be converted back into lead metal, lead oxide, and sulfuric acid. Everyone wishes lead sulfate could be dissolved safely, as this could be a way of recovering batteries that have been overly discharged. Lots of snake oil remedies have been created that tout to do just that... things like lime juice, ETDA, adding more sulfuric acid... AFAIK, none of them really work. Shorting in a wet (flooded) lead acid battery happens because the charging/discharging action causes the creation and destruction of lead sulfate, and because the lead sulfate is less dense than the lead and lead oxide it replaces, it flexes the plates. The flexing causes some of the lead sulfate to break free of the plates, and drop to the bottom of the cell. Because energy density is important in a lead acid battery, the manufacturer wastes as little space in the battery case as possible by putting the plates as close to the bottom of the battery jar as it dares. This allows the lead flakes to build up on the bottom until they reach the level of the plates and short them out. The gel cells, and glass mat cells short because the lead dendrites that sometimes grow as a result of charging/discharging, pierce the separator and short the plates directly. -Chuck Harris Neville Michie wrote: Hi, Lead acid cells have lead supports carrying lead oxide and lead metal active material in an electrolyte of sulphuric acid. When they discharge, the sulphuric acid electrolyte is reacted with the oxides and metal to form lead sulphate and the concentration of the acid falls, that is why garages used to check batteries with a hydrometer to measure the electrolyte concentration. At the same time the terminal voltage drops and the internal resistance rises, when the concentration of the electrolyte gets very low, the lead sulphate becomes soluble and will re-deposit all over the battery. With gel cells the electrolyte can be completely absorbed making the battery resistance infinitely high. If you can get some current to flow, you may be lucky enough to get the battery to reform some electrolyte, conduct some more, and eventually charge. However, when flat the lead sulphate dissolves and redeposits all over the battery, and when recharged will convert back to lead and lead oxide, often most inconveniently bridging the plates to a short circuit. The lesson is to not let the battery ever get flat. Lead acid batteries have some very good features. The terminal voltage rises as the concentration of the acid increases. So a constant voltage will charge a cell, and current stops flowing when the electrolyte reaches its proper concentration. The catch is, when you have a battery of several cells, if one cell gets weak, the others will be overcharged causing gassing and over concentration of the electrolyte. There is a judicious voltage that causes an acceptably low rate of gassing (the oxygen hydrogen catalytically recombining) that will keep the charges of cells equalised. But it only takes one total discharge event to cause enough leakage in one cell to bring about failure. Lead acid batteries are also environmentally excellent. They consist of nothing but pure lead and sulphuric acid and water. Sulphuric acid is not volatile so you can make batteries out of old batteries forever, recycling the acid, lead and water. If made on a large scale they are also very efficient (99.9% +) electrically. cheers, Neville Michie ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
