Maybe Lithium batteries in gliders not quite such a good idea yet?

On 1/19/2013 4:58 PM, wrote:
A lot of misinformation here. Read this instead:

http://www.luxresearchinc.com/news-a...eases/148.html

Keep in mind also that where there are problems is when recharging,
not discharging, so use in gliders is not a problem. Also, most ELTs
are shipped with lithium chemistry batteries now and have been used
in aircraft in Canada since 2008 so a lot of pilots are already
flying with them.

The ELT batteries are "primary" batteries, and are not rechargeable, so
I do not think they are relevant to our gliders. Since many pilots do
recharge batteries in their gliders, or in their homes, I think problems
when recharging are very relevant. Since we don't have much history with
Li-Fe batteries used in gliders or similar situations by people of
widely varying knowledge, and the drop-in units we can currently buy do
not seem to be well characterized, I am not keen to use them or
recommend them.

About a year ago, a group of us looked for batteries suitable for the
Perlan high-altitude glider. Because weight is critical to it's ability
to reach 90,000' and plenty of power is needed for all the systems, we
wanted the highest energy/kg we could safely get. Cost was a tertiary
issue. Eventually, we settled on the BA-5590, a primary lithium battery
used by the military for flights above about 60,000', and the
rechargeable BA-5390 for flights below 60,000'.

The two are physically identical, so they will fit in the same battery
box, but the primary battery has more energy per battery and per kg, but
at a much higher cost than the rechargeable battery. These batteries are
highly characterized and have plenty of history, so we believe they can
be trusted in the extreme conditions the Perlan will encounter.

We did try to get Li-Fe battery packs from Saft, but they weren't
interested in custom orders. Companies that would do custom orders
tended to be small assemblers of cells made in China by various
companies whose reliability we could not determine to our satisfaction.
I'm sure this situation will change in time, perhaps this year, but
we're not there yet, I think.

It was a definite disappointment we couldn't get the Saft batteries, as
they seemed almost ideal for gliders.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

On Sunday, January 20, 2013 1:44:23 PM UTC-5, Eric Greenwell wrote:
It was a definite disappointment we couldn't get the Saft batteries,

Because of the hazards associated with battery misuse, SAFT will
*only* sell to qualified organizations. Its expensive for them
to qualify an organization and application, so small custom
lots are out of the question...

as they seemed almost ideal for gliders.

Yes, SAFT make some cells that are ideal, hence use in Antares...

Best Regards, Dave

On 1/20/2013 10:51 AM, Dave Nadler wrote:
On Sunday, January 20, 2013 1:44:23 PM UTC-5, Eric Greenwell wrote:
It was a definite disappointment we couldn't get the Saft
batteries,

Because of the hazards associated with battery misuse, SAFT will
*only* sell to qualified organizations. Its expensive for them to
qualify an organization and application, so small custom lots are out
of the question...

as they seemed almost ideal for gliders.

Yes, SAFT make some cells that are ideal, hence use in Antares...

Hmm, maybe the Perlan Project could buy some "spare" Saft cells from
Antares, in anticipation of ordering an entire glider ... eventually.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)