And Speaking of Batteries and Center of Gravity

[Dan Marotta]

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

[Matt Herron Jr.]

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???

[Pat]

Don't forget to take into account the new definition of a kilogram.

[Emir Sherbi]

A plastic container with concrete?

[[email protected]]

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.

[Mike the Strike]

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

[Michael Opitz]

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

[JS[_5_]]

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/collections/12v-series-lifepo4-batteries/products/copy-of-12v-3ah-lfp-battery-pvc-blf-1203a
The two power connectors are wired in parallel.
Jim

[Michael Opitz]

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/collections/12v-series-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

[Dan Marotta]

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

[Dan Marotta]

What's a kilogram?Â* I use pounds.

On 11/16/2018 10:37 AM, Pat wrote:
> Don't forget to take into account the new definition of a kilogram.

--
Dan, 5J

[Dan Marotta]

Lighter than lead.

On 11/16/2018 10:37 AM, Emir Sherbi wrote:
> A plastic container with concrete?

--
Dan, 5J

[Dan Marotta]

That's encouraging!

On 11/16/2018 11:41 AM, 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....
>

--
Dan, 5J

[Dan Marotta]

I already have a brass tail wheel and, since the Stemme is certificated
and the charging system is designed for lead/acid batteries, there won't
be any LiFePO4 batteries installed.Â* I am, however, looking at using a
LiFePO4 as a portable battery which I can plug in when needed, isolated
from the other batteries and charging system, of course.

On 11/16/2018 6:36 PM, 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
>

--
Dan, 5J

[Darryl Ramm]

On Friday, November 16, 2018 at 9:57:09 AM UTC-8, wrote:
> 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.

The electrolyte is not a gel in mat, it's just a liquid in mat and there is very little of it. If you wanted to flush it out it would be easy with plain water. You are likely confusing the common VRLA/AGM (Valve Regulated Lead Acid/Absorbent Glass Mat) battery with a "gel" battery, which almost nobody uses today. Thickening the electrolyte in an AGM battery would reduce performance.

Just leave the battery as is. There is likely no issue with freezing since there is so much air space in the mat electrolyte carriers. I've frozen multiple VRLA/AGM batteries for testing. And there is such little electrolyte in these batteries will be irrelevant for W&B issues.

[Mike C]

On Friday, November 16, 2018 at 8:23:25 PM UTC-7, Dan Marotta wrote:
> 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

Lead shot/epoxy slurry mix can be molded into about any shape and is relatively easy to source. Used it to make tail weights for my RS15.

Also lead wool can be found in hardware stores and is easily melted with a propane torch.

Mike (4)

[Jim White[_3_]]

At 05:36 17 November 2018, Mike C wrote:
>
>Lead shot/epoxy slurry mix can be molded into about any shape and is
>relati=
>vely easy to source. Used it to make tail weights for my RS15.
>
>Also lead wool can be found in hardware stores and is easily melted with
a
>=
>propane torch.
>
>Mike (4)
>
In the UK one can buy lead flashing from the builders merchant. This is a
roll of thin lead sheet about 6 inches wide. Just fold it several times
lengthwise into a paperback shaped weight, wrap with duct tape and drop it
in the slot. About ten minutes work.

[[email protected]]

I also own a S10 VT and just replaced the tail battery for a new one. I find that on long flights with poor insolation it is good to have more amp.hours
Sergio