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And Speaking of Batteries and Center of Gravity
I'm thinking of eliminating the tail battery in my Stemme but need the
weight for proper balance.Â* I know I could replace it with pure lead, but that's a lot of work so I've come up with a plan that would be more satisfying and I would like comments and/or suggestions. My thought is to discharge the battery fully.Â* It's a standard AGM that everyone uses.Â* Then drill a couple of holes in the case and flush out the electrolyte a couple of times with water.Â* Then fill the case up with a highly saturated solution of NaHCO3, baking soda if I have the formula correctly, and completely neutralize any remaining acid.Â* A final flush with pure water, let it dry out, and finally, I could add just about anything inert to bump the weight back up to what it was, and plug the holes.Â* Voila!Â* A perfectly sized ballast weight. Comments?Â* Have I missed anything? -- Dan, 5J |
#2
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And Speaking of Batteries and Center of Gravity
On Friday, November 16, 2018 at 9:24:20 AM UTC-8, Dan Marotta wrote:
I'm thinking of eliminating the tail battery in my Stemme but need the weight for proper balance.Â* I know I could replace it with pure lead, but that's a lot of work so I've come up with a plan that would be more satisfying and I would like comments and/or suggestions. My thought is to discharge the battery fully.Â* It's a standard AGM that everyone uses.Â* Then drill a couple of holes in the case and flush out the electrolyte a couple of times with water.Â* Then fill the case up with a highly saturated solution of NaHCO3, baking soda if I have the formula correctly, and completely neutralize any remaining acid.Â* A final flush with pure water, let it dry out, and finally, I could add just about anything inert to bump the weight back up to what it was, and plug the holes.Â* Voila!Â* A perfectly sized ballast weight. Comments?Â* Have I missed anything? -- Dan, 5J thats less work than a lump of lead and a block of foam??? |
#3
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And Speaking of Batteries and Center of Gravity
Don't forget to take into account the new definition of a kilogram.
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And Speaking of Batteries and Center of Gravity
A plastic container with concrete?
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#5
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And Speaking of Batteries and Center of Gravity
On Friday, November 16, 2018 at 12:24:20 PM UTC-5, Dan Marotta wrote:
I'm thinking of eliminating the tail battery in my Stemme but need the weight for proper balance.Â* I know I could replace it with pure lead, but that's a lot of work so I've come up with a plan that would be more satisfying and I would like comments and/or suggestions. My thought is to discharge the battery fully.Â* It's a standard AGM that everyone uses.Â* Then drill a couple of holes in the case and flush out the electrolyte a couple of times with water.Â* Then fill the case up with a highly saturated solution of NaHCO3, baking soda if I have the formula correctly, and completely neutralize any remaining acid.Â* A final flush with pure water, let it dry out, and finally, I could add just about anything inert to bump the weight back up to what it was, and plug the holes.Â* Voila!Â* A perfectly sized ballast weight. Comments?Â* Have I missed anything? -- Dan, 5J Unlike a "wet cell" battery, the electrolyte in the AGM (SLA) is semi-solid (gel in mat) and flushing it out would be difficult. Why not simply leave the battery as-is? You can disconnect it from the electrical system but there is no need to flush it. Just inspect it every few months to check whether it is cracking up or anything. And replace with another old battery after a few years. I havn't had such a battery leak yet, including some that are 20+ years old (they're not in my glider!). One caveat: the electrolyte can freeze at low enough temperatures. To avoid that, the battery should be fully charged. Even if it's an old battery with reduced capacity you can still charge it as much as it will take. Such batteries can hold the charge for a year or more. |
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And Speaking of Batteries and Center of Gravity
On Friday, November 16, 2018 at 11:45:04 AM UTC-7, Dave Walsh wrote:
At 17:37 16 November 2018, Emir Sherbi wrote: A plastic container with concrete? Eh? What is wrong with just leaving the existing battery in the tail? I've several "dead" lead acid batteries from the days I owned a DG400: they're now nearly 20 years old, all are perfect physically, no swelling, no leakage.... Yep - my Discus 2 tail battery sat unused in the Arizona heat for ten years and remained intact with no leaks. Using that weight is a lot easier than reducing the mass ahead of the CG! Mike |
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And Speaking of Batteries and Center of Gravity
At 00:25 17 November 2018, Mike the Strike wrote:
On Friday, November 16, 2018 at 11:45:04 AM UTC-7, Dave Walsh wrote: At 17:37 16 November 2018, Emir Sherbi wrote: A plastic container with concrete? Eh? What is wrong with just leaving the existing battery in the tail? I've several "dead" lead acid batteries from the days I owned a DG400: they're now nearly 20 years old, all are perfect physically, no swelling, no leakage.... Yep - my Discus 2 tail battery sat unused in the Arizona heat for ten years and remained intact with no leaks. Using that weight is a lot easier than reducing the mass ahead of the CG! Mike When I went to a LiFePo battery for my main power because of the current drain from the modern instruments, I found that the lead acid tail battery didn't provide enough power to last as long as I'd like for a true backup to last. My solution was to buy a second LiFePo battery and install it next to the main one in the wheel well area battery compartment in my D-2b. I have looked for a LiFePo battery that fits in the tail fin, but the only ones that I found were frightfully expensive. I also imagine that a LiFePo tail battery would be a lot lighter than a lead-acid one as well, and that would necessitate adding other weights somehow. What I did, was to find a used solid brass tail wheel hub on the German want ads, and utilized that to replace the SH plastic hub. This moves the tail weight to a lot lower point on the boom, which is a good thing in case of a ground loop. The only bad thing is that the glider weight and balance is now set up just for me, and if I want to let a lighter person fly it, then we have to add seat weights. If I were still using the tail battery for weight, then all I'd have to do would be to remove it, and the lighter pilot wouldn't have to deal with extra weights in the cockpit. RO |
#8
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And Speaking of Batteries and Center of Gravity
On Friday, November 16, 2018 at 5:45:04 PM UTC-8, Michael Opitz wrote:
At 00:25 17 November 2018, Mike the Strike wrote: On Friday, November 16, 2018 at 11:45:04 AM UTC-7, Dave Walsh wrote: At 17:37 16 November 2018, Emir Sherbi wrote: A plastic container with concrete? Eh? What is wrong with just leaving the existing battery in the tail? I've several "dead" lead acid batteries from the days I owned a DG400: they're now nearly 20 years old, all are perfect physically, no swelling, no leakage.... Yep - my Discus 2 tail battery sat unused in the Arizona heat for ten years and remained intact with no leaks. Using that weight is a lot easier than reducing the mass ahead of the CG! Mike When I went to a LiFePo battery for my main power because of the current drain from the modern instruments, I found that the lead acid tail battery didn't provide enough power to last as long as I'd like for a true backup to last. My solution was to buy a second LiFePo battery and install it next to the main one in the wheel well area battery compartment in my D-2b. I have looked for a LiFePo battery that fits in the tail fin, but the only ones that I found were frightfully expensive. I also imagine that a LiFePo tail battery would be a lot lighter than a lead-acid one as well, and that would necessitate adding other weights somehow. What I did, was to find a used solid brass tail wheel hub on the German want ads, and utilized that to replace the SH plastic hub. This moves the tail weight to a lot lower point on the boom, which is a good thing in case of a ground loop. The only bad thing is that the glider weight and balance is now set up just for me, and if I want to let a lighter person fly it, then we have to add seat weights. If I were still using the tail battery for weight, then all I'd have to do would be to remove it, and the lighter pilot wouldn't have to deal with extra weights in the cockpit. RO This $50 3AH Bioenno LiFePO4 in a box made from paint stirring sticks, foam and heat shrink, also including two 1kg lead weights fits in the Schleicher tail battery compartment. Two batteries would fit, but may not be heavy enough. https://www.bioennopower.com/collect...-pvc-blf-1203a The two power connectors are wired in parallel. Jim |
#9
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And Speaking of Batteries and Center of Gravity
At 01:59 17 November 2018, JS wrote:
On Friday, November 16, 2018 at 5:45:04 PM UTC-8, Michael Opitz wrote: At 00:25 17 November 2018, Mike the Strike wrote: On Friday, November 16, 2018 at 11:45:04 AM UTC-7, Dave Walsh wrote: At 17:37 16 November 2018, Emir Sherbi wrote: A plastic container with concrete? Eh? What is wrong with just leaving the existing battery in the tail? I've several "dead" lead acid batteries from the days I owned a DG400: they're now nearly 20 years old, all are perfect physically, no swelling, no leakage.... Yep - my Discus 2 tail battery sat unused in the Arizona heat for ten years and remained intact with no leaks. Using that weight is a lot easier than reducing the mass ahead of the CG! Mike When I went to a LiFePo battery for my main power because of the current drain from the modern instruments, I found that the lead acid tail battery didn't provide enough power to last as long as I'd like for a true backup to last. My solution was to buy a second LiFePo battery and install it next to the main one in the wheel well area battery compartment in my D-2b. I have looked for a LiFePo battery that fits in the tail fin, but the only ones that I found were frightfully expensive. I also imagine that a LiFePo tail battery would be a lot lighter than a lead-acid one as well, and that would necessitate adding other weights somehow. What I did, was to find a used solid brass tail wheel hub on the German want ads, and utilized that to replace the SH plastic hub. This moves the tail weight to a lot lower point on the boom, which is a good thing in case of a ground loop. The only bad thing is that the glider weight and balance is now set up just for me, and if I want to let a lighter person fly it, then we have to add seat weights. If I were still using the tail battery for weight, then all I'd have to do would be to remove it, and the lighter pilot wouldn't have to deal with extra weights in the cockpit. RO This $50 3AH Bioenno LiFePO4 in a box made from paint stirring sticks, foam and heat shrink, also including two 1kg lead weights fits in the Schleicher tail battery compartment. Two batteries would fit, but may not be heavy enough. https://www.bioennopower.com/collect...eries-lifepo4- batteries/products/copy-of-12v-3ah-lfp-battery-pvc-blf-1203a The two power connectors are wired in parallel. Jim Thanks, I'll have a look. RO |
#10
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And Speaking of Batteries and Center of Gravity
Yeah, it'd be fun and I wouldn't have to source the lead, melt it, and
mold it to the right size/shape. On 11/16/2018 10:35 AM, Matt Herron Jr. wrote: On Friday, November 16, 2018 at 9:24:20 AM UTC-8, Dan Marotta wrote: I'm thinking of eliminating the tail battery in my Stemme but need the weight for proper balance.Â* I know I could replace it with pure lead, but that's a lot of work so I've come up with a plan that would be more satisfying and I would like comments and/or suggestions. My thought is to discharge the battery fully.Â* It's a standard AGM that everyone uses.Â* Then drill a couple of holes in the case and flush out the electrolyte a couple of times with water.Â* Then fill the case up with a highly saturated solution of NaHCO3, baking soda if I have the formula correctly, and completely neutralize any remaining acid.Â* A final flush with pure water, let it dry out, and finally, I could add just about anything inert to bump the weight back up to what it was, and plug the holes.Â* Voila!Â* A perfectly sized ballast weight. Comments?Â* Have I missed anything? -- Dan, 5J thats less work than a lump of lead and a block of foam??? -- Dan, 5J |
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