[amsat-bb] Re: [suitsat2] ARISSat-1 Battery
Hi Phil, Yes, that is correct. 73, Tony AA2TX --- On 8/15/2011 1:26 AM, Phil Karn wrote: On 8/14/11 6:11 PM, Anthony Monteiro wrote: Yes, Zinc dendrites will form also if the battery is overcharged but we should not be able to do that on ARISSat-1 so only the silver ones should be an issue. Oh, so they form on both plates. Interesting. Charging the battery plates out zinc metal on the negative plates, but any metallic silver on the positive plates should be oxidized back to silver oxide. Silver dendrites should form only during discharge, right? -Phil ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: [suitsat2] ARISSat-1 Battery
On 8/14/11 6:11 PM, Anthony Monteiro wrote: > Yes, Zinc dendrites will form also if the battery is > overcharged but we should not be able to do that on > ARISSat-1 so only the silver ones should be an issue. Oh, so they form on both plates. Interesting. Charging the battery plates out zinc metal on the negative plates, but any metallic silver on the positive plates should be oxidized back to silver oxide. Silver dendrites should form only during discharge, right? -Phil ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: [suitsat2] ARISSat-1 Battery
Hi Phil, I think the initial dendrites DO just spark and open up but eventually the spacer is damaged and the short is enough to bring the cell voltage down. Yes, Zinc dendrites will form also if the battery is overcharged but we should not be able to do that on ARISSat-1 so only the silver ones should be an issue. 73, Tony AA2TX --- On 8/14/2011 6:56 PM, Phil Karn wrote: On 8/14/11 3:18 PM, Anthony Monteiro wrote: I think the explanation is that the battery experienced a significant event on Aug 11 where it lost the electrolyte in one or more cells. If this is true, the bad news is that it will no longer hold a charge and will not operate in eclipse any more. I agree with your analysis in that one or more cells seems to have gone open-circuit, or at least greatly reduced in capacity. If you know these batteries and their specific failure mechanisms, then I'd say your lost electrolyte theory is a pretty good one. I never have understood why the dendrites would not be melted by high current as soon as they crossed the gap between the two plates. I assume they grow on the zinc plates as the battery is charged? -Phil ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: [suitsat2] ARISSat-1 Battery
On 8/14/11 3:18 PM, Anthony Monteiro wrote: > I think the explanation is that the battery experienced a > significant event on Aug 11 where it lost the electrolyte > in one or more cells. If this is true, the bad news is > that it will no longer hold a charge and will not operate > in eclipse any more. I agree with your analysis in that one or more cells seems to have gone open-circuit, or at least greatly reduced in capacity. If you know these batteries and their specific failure mechanisms, then I'd say your lost electrolyte theory is a pretty good one. I never have understood why the dendrites would not be melted by high current as soon as they crossed the gap between the two plates. I assume they grow on the zinc plates as the battery is charged? -Phil ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
