More grist for the battle of the battery

John Ferguson wrote:
Been reading this thread and found the discussion quite
interesting, interesting enough to go looking. I found
this site selling L-ION batteries, charge protectors
and special L-ION chargers all at very reasonable prices.

http://www.batteryspace.com/index.as...WCATS&Category
=489

One part of this discussion has been about not doing
it yourself, would making a battery out of these parts
constitute doing it yourself for someone reasonably
proficient and capable of taking care in assembly of
such a pack.

I don't intend to be facetious when I say "If you have to ask, don't do
it yourself!" Assembling the pack is not the issue, but charging it
properly and protecting it from overheating, mechanical damage, and
probably other issues I'm not familiar with. Li-ion cells are not
tolerant of poor charging methods compared to lead acid cells, ni-cads,
or even Ni-mh cells. The external laptop batteries we are discussing are
packaged units designed and manufactured expressly for that use, and
come with a charger matched to the unit, so I think they would work
better and be much safer than most of us could construct. Even so, it's
not obvious (yet) that they are actually compatible with glider usage,
given the temperature and altitude ranges we fly in.

I fly a turbo and regaining about 6 kilo of battery
weight is attractive as I stand about 90 kilos ready
to fly.

Are you thinking of using a Li-ion battery for the starter battery?
Don't even think of going there!

--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

"Eric Greenwell" wrote in message
...
John Ferguson wrote:
Been reading this thread and found the discussion quite
interesting, interesting enough to go looking. I found
this site selling L-ION batteries, charge protectors
and special L-ION chargers all at very reasonable prices.

http://www.batteryspace.com/index.as...WCATS&Category
=489

One part of this discussion has been about not doing
it yourself, would making a battery out of these parts
constitute doing it yourself for someone reasonably
proficient and capable of taking care in assembly of
such a pack.

I don't intend to be facetious when I say "If you have to ask, don't do
it yourself!" Assembling the pack is not the issue, but charging it
properly and protecting it from overheating, mechanical damage, and
probably other issues I'm not familiar with. Li-ion cells are not
tolerant of poor charging methods compared to lead acid cells, ni-cads,
or even Ni-mh cells. The external laptop batteries we are discussing are
packaged units designed and manufactured expressly for that use, and
come with a charger matched to the unit, so I think they would work
better and be much safer than most of us could construct. Even so, it's
not obvious (yet) that they are actually compatible with glider usage,
given the temperature and altitude ranges we fly in.

I fly a turbo and regaining about 6 kilo of battery
weight is attractive as I stand about 90 kilos ready
to fly.

Are you thinking of using a Li-ion battery for the starter battery?
Don't even think of going there!

--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

I don't think it's fair to say that Li-ion in some form wouldn't work as a
starter battery. It is fair to say we don't yet know all the issues
involved. And it's fair to say, as Eric does, that it isn't a DIY project.
Maybe it will be someday soon. Let someone else develop them for a similar
application and then adopt it.

Li-Ion will be used as hybrid car batteries as soon as the price is
workable. They are already being used in research electric vehicles in
Japan that get 400KM range @ 120KPH on a charge and then completely recharge
in 5 minutes. The main problem, other than the battery price, is that
should everybody plug them in at the same time, the power grid would melt.

DeWalt will be introducing a set of construction grade power tools that use
these fast charge Li-Ion Polymer batteries next year.

As for temperature and altitude, I just can't see that as a problem. The
pressure delta from sea level to 40,000 feet is something like 10 PSI. The
cases have to be much stronger than that for safety reasons. Low
temperatures might cause a battery not in use to not develop full power at
switch-on but one in use would maintain its own temperature.

Bill Daniels

Bill Daniels wrote:

I don't think it's fair to say that Li-ion in some form wouldn't work as a
starter battery. It is fair to say we don't yet know all the issues
involved.

I agree. I was addressing John's situation. I'm sure a competent battery
engineer could design a good starter battery, though the voltages
available in Li-ion might be challenge for a 12 volt starter.

snip


As for temperature and altitude, I just can't see that as a problem. The
pressure delta from sea level to 40,000 feet is something like 10 PSI. The
cases have to be much stronger than that for safety reasons. Low
temperatures might cause a battery not in use to not develop full power at
switch-on but one in use would maintain its own temperature.

I suspect these batteries are probably fine for our conditions. The
problem (for me) is I don't know what's in the external laptop
batteries. Are all the components capable of 40,000'? If the pilot takes
off at 105 deg F with a battery at 130 deg F under the instrument
cowling and climbs to 20,000' in an hour, is the battery still OK, or is
it overheating under the load from the Ipaq, transponder, glide
computer, radio, etc.? Or maybe he just struggles around a few thousand
feet off the ground, while the battery temperature goes up? What then?

Sure, for pilots flying in temperatures under 90 deg F and less than
10,000', I'm not worried about the ambient conditions, but that leaves
out a lot of pilots in a lot of places.
--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA