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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#41
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What is that whiteish stuff on bad batteries (ruins stuff)?
On Tuesday, August 18, 2015 at 4:35:13 PM UTC-7, Jeff Liebermann wrote:
On Tue, 18 Aug 2015 12:01:51 -0700 (PDT), whit3rd wrote: On Tuesday, August 18, 2015 at 8:20:56 AM UTC-7, Jeff Liebermann wrote: On Mon, 17 Aug 2015 15:56:53 -0700 (PDT), wrote: Battery and ground contact areas eg terminals, clamps, frame connection areas are coated with a thin film of [silicone grease] suggested that he grease his sheet metal pieces before spot welding ... the grease exploded in the spot welder Yes, grease is good, but not in the current flow. There's formulations of grease that don't do that, of course; silicone takes high temperature, and some greases are intended for electrical conduction in thin films (they 'break down' at millivolts, and don't even get hot). http://store.caig.com/s.nl/sc.2/category.185/.f I've used this grease on rotating connections, at 40A it's just like a solid wire connection. Looks like aluminum dust, copper dust, graphite, and/or quartz(???). Can't be, it's transparent. It's based on a semiconductive component, which is nonlinear: insulating in bulk, but breaks down (in conductivity, not chemical nature) in thin films under electrical stress. US Patent #4696832 has more info. One your rotating joint connection, did you use brushes or a commutator to make the connection? If so, the path of least resistance is through these connections, not through the grease. It was bronze rubbing on a steel element; the grease keeps the steel from oxidizing while increasing the effective contact area. |
#42
Posted to sci.electronics.repair
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What is that whiteish stuff on bad batteries (ruins stuff)?
On Tue, 18 Aug 2015 16:58:50 -0700 (PDT), whit3rd
wrote: On Tuesday, August 18, 2015 at 4:35:13 PM UTC-7, Jeff Liebermann wrote: On Tue, 18 Aug 2015 12:01:51 -0700 (PDT), whit3rd wrote: On Tuesday, August 18, 2015 at 8:20:56 AM UTC-7, Jeff Liebermann wrote: On Mon, 17 Aug 2015 15:56:53 -0700 (PDT), wrote: Battery and ground contact areas eg terminals, clamps, frame connection areas are coated with a thin film of [silicone grease] suggested that he grease his sheet metal pieces before spot welding ... the grease exploded in the spot welder Yes, grease is good, but not in the current flow. There's formulations of grease that don't do that, of course; silicone takes high temperature, and some greases are intended for electrical conduction in thin films (they 'break down' at millivolts, and don't even get hot). http://store.caig.com/s.nl/sc.2/category.185/.f I've used this grease on rotating connections, at 40A it's just like a solid wire connection. Looks like aluminum dust, copper dust, graphite, and/or quartz(???). Can't be, it's transparent. It's based on a semiconductive component, which is nonlinear: insulating in bulk, but breaks down (in conductivity, not chemical nature) in thin films under electrical stress. US Patent #4696832 has more info. Never heard of that stuff, but if it's as you describe, it should be quite useful. How conductive, I don't know. The patent isn't very helpful: http://www.google.com/patents/US4696832 "The contact stabilization material comprises at least one block polymer or co-polymer of polyoxypropylene together with polyoxyethylene." It then points to a French patent: http://www.google.com/patents/EP0144399A1?cl=en which has a better explanation. I'll RTFM over the weeken. I got the Caig L260 and M260 info you linked came from: http://store.caig.com/s.nl/sc.18/category.1049/.f (Sorry I forgot to include the link. Kinda crazy today). Notice the mention of metallic filler. Is Caig L260 and M260 the right grease or should I be looking for something else? One your rotating joint connection, did you use brushes or a commutator to make the connection? If so, the path of least resistance is through these connections, not through the grease. It was bronze rubbing on a steel element; the grease keeps the steel from oxidizing while increasing the effective contact area. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#43
Posted to sci.electronics.repair
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What is that whiteish stuff on bad batteries (ruins stuff)?
On Tuesday, August 18, 2015 at 7:02:20 PM UTC-7, Jeff Liebermann wrote:
On Tue, 18 Aug 2015 16:58:50 -0700 (PDT), whit3rd wrote: ... some greases are intended for electrical conduction in thin films (they 'break down' at millivolts, and don't even get hot). http://store.caig.com/s.nl/sc.2/category.185/.f I've used this grease on rotating connections, at 40A it's just like a solid wire connection. Looks like aluminum dust, copper dust, graphite, and/or quartz(???). Can't be, it's transparent. It's based on a semiconductive component, which is nonlinear: insulating in bulk, but breaks down (in conductivity, not chemical nature) in thin films under electrical stress. US Patent #4696832 has more info. Never heard of that stuff, but if it's as you describe, it should be quite useful. How conductive, I don't know. The patent isn't very helpful: http://www.google.com/patents/US4696832 Yeah, there's a high information cost... and there's more boosterism than chemical physics in the sales lit. As to 'how conductive', the L260 variant that I used doesn't have conductive particles, so it only conducts in thin films, like rubbing parts would have around contact points. Because it is nonlinear, 'conductivity' is undefined (and the rubbing of bumpy surfaces mean the film thickness is likewise indefinite). Variants on this lubricant are recommended for slide potentiometers, I see. The admixture of conductive particles would make a grease conduct electricity, but that would be unsafe in electrical panels (and the intended uses include busbars). It would decalibrate potentiometers, too. Because metallic particles would constitute dissimilar metals in my mechanism, I didn't want to use such a grease. |
#44
Posted to sci.electronics.repair
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What is that whiteish stuff on bad batteries (ruins stuff)?
On Wednesday, August 19, 2015 at 4:20:17 AM UTC-4, whit3rd wrote:
On Tuesday, August 18, 2015 at 7:02:20 PM UTC-7, Jeff Liebermann wrote: On Tue, 18 Aug 2015 16:58:50 -0700 (PDT), whit3rd wrote: ... some greases are intended for electrical conduction in thin films (they 'break down' at millivolts, and don't even get hot). http://store.caig.com/s.nl/sc.2/category.185/.f I've used this grease on rotating connections, at 40A it's just like a solid wire connection. Looks like aluminum dust, copper dust, graphite, and/or quartz(???). Can't be, it's transparent. It's based on a semiconductive component, which is nonlinear: insulating in bulk, but breaks down (in conductivity, not chemical nature) in thin films under electrical stress. US Patent #4696832 has more info. Never heard of that stuff, but if it's as you describe, it should be quite useful. How conductive, I don't know. The patent isn't very helpful: http://www.google.com/patents/US4696832 Yeah, there's a high information cost... and there's more boosterism than chemical physics in the sales lit. As to 'how conductive', the L260 variant that I used doesn't have conductive particles, so it only conducts in thin films, like rubbing parts would have around contact points. Because it is nonlinear, 'conductivity' is undefined (and the rubbing of bumpy surfaces mean the film thickness is likewise indefinite). Variants on this lubricant are recommended for slide potentiometers, I see. The admixture of conductive particles would make a grease conduct electricity, but that would be unsafe in electrical panels (and the intended uses include busbars). It would decalibrate potentiometers, too. Because metallic particles would constitute dissimilar metals in my mechanism, I didn't want to use such a grease. MMMMMMMMMMMMMM use the artist's paintbrush not the zerkgun .... |
#45
Posted to sci.electronics.repair
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What is that whiteish stuff on bad batteries (ruins stuff)?
On Wed, 19 Aug 2015 01:20:09 -0700 (PDT), whit3rd
wrote: Yeah, there's a high information cost... and there's more boosterism than chemical physics in the sales lit. As to 'how conductive', the L260 variant that I used doesn't have conductive particles, so it only conducts in thin films, like rubbing parts would have around contact points. Because it is nonlinear, 'conductivity' is undefined (and the rubbing of bumpy surfaces mean the film thickness is likewise indefinite). Variants on this lubricant are recommended for slide potentiometers, I see. The admixture of conductive particles would make a grease conduct electricity, but that would be unsafe in electrical panels (and the intended uses include busbars). It would decalibrate potentiometers, too. Because metallic particles would constitute dissimilar metals in my mechanism, I didn't want to use such a grease. If the stuff works as you describe, then it should change conductivity from a bad insulator to a marginal conductor when pressure is applied. That got my interest because I have an application for a cheap pressure sensing system, that will work with rollers and gears. In theory, I could monitor the conductivity between meshed gears, which would give me an indication of the applied pressure or changes in pressure. However, I don't think it works the way you suggest[1]. The grease simply prevents surface oxidation and displaces electrolytes to reduce galavanic corrosion if the mating surfaces are dissimilar meatals. Doping it with conductive particles also helps reduce galvanic corrosion. When I read the vague and misleading promotional literature from that point of view, the claims seems to make sense. On the other foot, there are specialized greases that allegedly work the way you describe. I found a hint at: https://www.linkedin.com/grp/post/1786018-215513373 but could not find any specifics. I'll dig more later. I also haven't had time to read through the patents yet but I'll get to it this weekend. [1] increased pressure = thin film = increased conductivity -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#46
Posted to sci.electronics.repair
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What is that whiteish stuff on bad batteries (ruins stuff)?
In article ,
Jeff Liebermann wrote: Can't be, it's transparent. It's based on a semiconductive component, which is nonlinear: insulating in bulk, but breaks down (in conductivity, not chemical nature) in thin films under electrical stress. US Patent #4696832 has more info. Never heard of that stuff, but if it's as you describe, it should be quite useful. How conductive, I don't know. This material is better known as "Stabilant 22" (often used as "Stabilant 22A", diluted in alcohol). Years ago, Stabilant 22A was remarketed to the audiophile community (in small syringes, probably with a huge mark-up) under the name "Tweek". I've used it for quite a few years. It definitely seems to help maintain electrical connections between contacts. Quite useful for (e.g.) finger contacts on PCI cards... it has restored reliable operation for cards which were intermittent, when a simple "unplug, clean, and re-plug" cycling didn't help. |
#47
Posted to sci.electronics.repair
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What is that whiteish stuff on bad batteries (ruins stuff)?
Jeff Liebermann wrote:
On Wed, 19 Aug 2015 01:20:09 -0700 (PDT), whit3rd wrote: Yeah, there's a high information cost... and there's more boosterism than chemical physics in the sales lit. As to 'how conductive', the L260 variant that I used doesn't have conductive particles, so it only conducts in thin films, like rubbing parts would have around contact points. Because it is nonlinear, 'conductivity' is undefined (and the rubbing of bumpy surfaces mean the film thickness is likewise indefinite). Variants on this lubricant are recommended for slide potentiometers, I see. The admixture of conductive particles would make a grease conduct electricity, but that would be unsafe in electrical panels (and the intended uses include busbars). It would decalibrate potentiometers, too. Because metallic particles would constitute dissimilar metals in my mechanism, I didn't want to use such a grease. If the stuff works as you describe, then it should change conductivity from a bad insulator to a marginal conductor when pressure is applied. That got my interest because I have an application for a cheap pressure sensing system, that will work with rollers and gears. In theory, I could monitor the conductivity between meshed gears, which would give me an indication of the applied pressure or changes in pressure. However, I don't think it works the way you suggest[1]. The grease simply prevents surface oxidation and displaces electrolytes to reduce galavanic corrosion if the mating surfaces are dissimilar meatals. Doping it with conductive particles also helps reduce galvanic corrosion. When I read the vague and misleading promotional literature from that point of view, the claims seems to make sense. On the other foot, there are specialized greases that allegedly work the way you describe. I found a hint at: https://www.linkedin.com/grp/post/1786018-215513373 but could not find any specifics. I'll dig more later. I also haven't had time to read through the patents yet but I'll get to it this weekend. [1] increased pressure = thin film = increased conductivity I still have cramolin copper grease. I never used it on anything. Seems like it had little conductivity with test leads. Greg |
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