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

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???

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

A plastic container with concrete?

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.

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

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

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

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

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