LiPo Batteries in Gliders

On Feb 25, 7:56*am, bildan wrote:
On Feb 25, 8:48*am, Mike the Strike wrote:

Years ago, a lab next to the one I worked in had experimental
batteries under development. *All the high energy density ones utilize
very reactive elements, of which lithium is one. *However, nothing
would beat the sodium-sulfur battery in its capacity to "go
Vesuvius". *It was colloquially referred to as "the fire and brimstone
battery". *The lab had a sulfurous smell that reminded one of the
entrance to nether regions.

I'm going to stick with lead-acid, thanks very much!

Mike

If you think lead-acid gel-cells are safe, try a dead short on a fully
charged one. *Splattering hot gelled acid is pretty nasty stuff.

Who exactly flies with gel-cells? There is no gelled anything inside
the VRLA (Valve Regulated Lead Acid) aka SLA (Sealed Lead Acid) or
often incorrectly called "gell cell" batteries almost universally used
in gliders. There is a surprisingly small amount of liquid
electrolyte, sulfuric acid electrolyte, basically the same as inside a
regular car battery but here used to moisten the thin fiberglass mats
between the plates.

But yes the dead short scenario is a worry and people need to be
careful. These little batteries can source hundreds of amps. Most
likely is not a destructive failure of the VRLA battery but damage
caused by the wire shorting across the battery, getting red hot,
burning molten PVC insulation, etc. burning somebody or causing a
fire. There is a misconception as well that VRLA/SLA batteries are
sealed and they will explode if the pressure inside gets too high.
They are vented with neoprene valves that will release pressure so
they won't just pressurize and eventually explode, but they still can
suffer catastrophic case failure in some situations. And they can also
cause explosions if overcharged in confined spaces from the hydrogen
leaking out the neoprene valves.

Darryl

On Feb 25, 7:56*am, bildan wrote:
On Feb 25, 8:48*am, Mike the Strike wrote:

Years ago, a lab next to the one I worked in had experimental
batteries under development. *All the high energy density ones utilize
very reactive elements, of which lithium is one. *However, nothing
would beat the sodium-sulfur battery in its capacity to "go
Vesuvius". *It was colloquially referred to as "the fire and brimstone
battery". *The lab had a sulfurous smell that reminded one of the
entrance to nether regions.

I'm going to stick with lead-acid, thanks very much!

Mike

If you think lead-acid gel-cells are safe, try a dead short on a fully
charged one. *Splattering hot gelled acid is pretty nasty stuff.

That's why it's a good idea to use a FUSE and keep the terminals
covered. I can't think of any high capacity battery that won't react
spectacularly to a dead short.

On Feb 25, 6:03*am, "Karl Striedieck" wrote:
While charging a LiPo model airplane battery with a top-of-the-line charger
at the proper rate it burst into flame. I had carelessly left it out of the
flame-proof charge bag and when I checked strange noises the room was filled
with acrid smoke and a Mt Vesuvius mass of sputtering pyrotchnics was
burning a hole in the work bench. Don't fly with you-do-it LiPos unless you
have an ejection seat!

Karl Striedieck

"johngalloway" wrote in message

...



What about Li Ion batteries like these? *Is the fire risk sinificantly
less than Li Polymer?

http://www.streckenflug.at//shop/pro...roducts_id=608

A bit pricey, and probably not approved in Europe, *but might be a
thought when a transponder has to be carried.

John Galloway

Here's an intersting video of a laptop battery fire.

http://www.youtube.com/watch?v=mlZggVrF9VI

Jim

"Michael Huber" wrote

I do use A123 LiFe cells (different chemistry than LiPo!) in my self
launcher and I am very happy with the power and capacity they offer.

I agree, with using A123 cells. They are coming down in price, pretty
rapidly too, I think. Shoot, even Lowe's hardware and lumber stores are
selling them!
--
Jim in NC

I agree, with using A123 cells. *They are coming down in price, pretty
rapidly too, I think. *Shoot, even Lowe's hardware and lumber stores are
selling them!


Are these the same type of batteries that you find in cordless drills?

On Feb 24, 10:50*pm, GM wrote:
Hi,

it's still winter with lousy weather in the northern hemisphere, so it
is time to warm up an old discussion. I searched the forum for threads
reg. Lithium-Polymer Batteries and there have been none for a while.
Here are the questions:
- Does anyone have real life experience with LiPo's in a glider? (real
gliders, that is - not models)
- Can I combine two 7.4V packs in series to get a 14.8V unit or is
there a risk with that?
- How would one charge a combo like this? Each unit by itself and then
hook them together or with one charger while hooked together?

The prices have dropped to a very affordable level; so have the
chargers/balancers. The weight savings are considerable. My 12V/7.5Ah
standard sealed gel-cell weighs 2.35kg (5.17lbs) and it lasts a few
days. *I found two 7.4V/5.0Ah units on e-bay that weigh in at 0.3kg
each (0.6kg or 1.32 lbs in total)

Any input is welcome.

Uli Neumann
'GM'

Uli, call me. I just bought a 12V 10 Ah Lithium Phosphate battery
from K2. It comes in the same physical package as a 7 Ah 12 V SLA
battery, it much lighter than a normal SLA battery and my preliminary
tests indicates it has a useful capacity almost equal to a 12 Ah SLA
battery. It has a circuit board in it to balance the individual cell
charge while charging, and it includes over discharge protection as
well. This looks like a safe alternative to the SLA batteries and if
you factor in the increased number of cycles available, its going to
be cheaper in the long run.

SF

On Feb 25, 5:21*pm, joesimmers wrote:
I agree, with using A123 cells. *They are coming down in price, pretty
rapidly too, I think. *Shoot, even Lowe's hardware and lumber stores are
selling them!

Are these the same type of batteries that you find in cordless drills?

The A123 cells, is a specific type of Li battery. LiFe aka Lithium
Iron Phosphate or sometimes stated as "Lithium Iron" but not to be
confused with Lithium-Ion (the standard Li chemistry). There are
several other Li chemistries in use. e.g. don't confuse the A123 LiFe
secondary battery with the LiFeS2 (Lithium Iron Disulfide) primary
battery chemistry used in ELT and PLB batteries and in the Energizer
e2 batteries for use in the SPOT messenger.

Nowadays cordless drills likely run on NiMh (Nickel metal hydride) or
standard Li-Ion or yes some do have the A123 cells.

Darryl

"Darryl Ramm" wrote

Geez where is your man tool lust? :-)

DeWalt 36 Volt systems uses the A123 batteries or t least their
chemistry (DeWalt may call that nano-phosphate, same stuff, different
name). I think there are companies using that, and there have been
disputes between companies maybe breaching A123 patents/IP).

My SureFire tactical flashlights run on CR123A Lithium.

I have plenty power tool lust, but not the wallet to match it! :-)

I am locked in, so to speak, to the B & D firestorm line of battery powered
18 volt tools. At last count, I have 11 functioning batteries, 4 drills
(one is a 1/2" hammer drill) an impact driver, two radios, 3 rapid chargers,
circular saw, reciprocating saw, two random orbital sanders, chain saw,
flashlight, dustbuster type vacuum, and probably a couple other tools that I
have forgotten to mention.

To replace them with the latest and greatest technology now available would
be overly expensive. If I need more power than 18 volts, I have plenty of
plug in tools, a 2500 watt inverter, and a 2200 watt Honda generator. Until
all of the B & D tools die, (they don't seem to die even with very tough
use, building houses and more) I'll stick with what I have, and "try" to
ignore all the new stuff. It's better that way. "sniff, sniff." ;-)
--
Jim in NC

Wow - I hit the motherlode of info on this subject!
Berry had it right: the main reason for me looking into this
technology is to save weight. You guys in ships that can load enough
water to turn any desert into a green garden of Eden have no idea how
difficult it is to stay under a MTOW of 667#. Reducing the weight of
the battery while maintaining the capacity is a consideration and yes
- I am shedding pounds through diet and exercise, too! ;-)
Uli

GM wrote:
Wow - I hit the motherlode of info on this subject!
Berry had it right: the main reason for me looking into this
technology is to save weight. You guys in ships that can load enough
water to turn any desert into a green garden of Eden have no idea how
difficult it is to stay under a MTOW of 667#. Reducing the weight of
the battery while maintaining the capacity is a consideration and yes
- I am shedding pounds through diet and exercise, too! ;-)

The Streckenflug battery is the best choice I've seen so far in a
lithium battery for a glider, as long as your equipment can take the 16+
volts it starts out at. Many of the radios and transponders operate at
10-30 volts, so no problem there, but your logger, vario, etc may not.

At 550 euro for the battery and charger, it's almost $200/pound to save
weight that way! Great diet incentive, I suppose. Still, could be worth
it in some circumstances.

--
Eric Greenwell - Washington State, USA (netto to net to email me)

- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm http://tinyurl.com/yb3xywl

- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what you need to know tinyurl.com/yfs7tnz