Lithium technology batteries

On Sun, 19 Dec 2004 19:09:49 +0000 (UTC), tango4 wrote:

"WilLiscomb" wrote in message
...
voltage regulator
williscomb



Hmmmm

Build a 'better' battery so that you can dump power into a voltage
regulator. Cute.

Actually the forward biased semiconductor junction in the form of a diode is
a much easier way to do things.

Ian

Only problem is that the voltage drop is also present at the
end-of-charge point, thus losing the last 0.7v of possible battery
voltage before things start working strangely.
If you use a well designed switching regulator which can boost as well
as buck, the voltage supplied to the instruments can be maintained in
the ideal range until the battery is almost completely flat, and at an
average efficiency of about 80%. AFAIK, complete discharge is not
harmful to NiCd, Lithium types etc. It is harmful to lead acid
batteries.
Cheers, John G.

"Tim Ward" wrote in message
nk.net...

"Eric Greenwell" wrote in message
...
Ken Kochanski (KK) wrote:

Although the technology is still pricy vs lead-acid batteries, the
power/weight/size vs cost equation is getting better. Anybody using
lithium model airplane packs bundeled to produce 12 - 14 v @3 - 6
amps
as a power source for their glider? (I have been looking at the
duralite site ... I'm sure there are others.)
http://www.duralitebatteries.com/batteries.html

The recommended
safe charging procedure for all Li-ion & Li-Poly
batteries is to charge them out of the aircraft in a ?re
proof area or container. Always be present during the
charging cycle. Unplug the batteries from charger when
charging cycle is complete.


I think this applies only to the first generation electric powered model
airplane batteries. There are tens of millions of lithium ion and lithium
polymer cellphone batteries charged on nightstands with few problems. Where
there were problems it has turned out to be counterfeit made in China
aftermarket batteries. Even the second generation model airplane batteries
have pretty well put the fire problem behind them.

Why Li-Po? Well one reason is that their light weight allows them to be
placed just behind the instrument panel where very short power leads lose
less power. Heavy SLA's usually have to go behind the seat and use long
wires to the panel.

Bill Daniels

These retailers are expensive - go to the source
http://sabahoceanic.com/SearchResult.aspx?CategoryID=9
They will tag them for free
Use 8x BR-C and you will get 12V 10000mah for $128
(these are 3v cells as opposed to the normal 3.7v)

Can do it cheaper with some of the other cells

Used them to replace my laptop batts - fast efficient service. Downside is
that chargers & electronics are scarce
rgds
Stephen

"Atacdad" wrote in message
...
I looked at these guys earlier this year. Unfortuneately, they did not
have an "off the shelf" solution. Lithium without the fire hazard....

http://www.valence.com

AT


"Ken Kochanski (KK)" wrote in message
oups.com...
Although the technology is still pricy vs lead-acid batteries, the
power/weight/size vs cost equation is getting better. Anybody using
lithium model airplane packs bundeled to produce 12 - 14 v @3 - 6 amps
as a power source for their glider? (I have been looking at the
duralite site ... I'm sure there are others.)
http://www.duralitebatteries.com/batteries.html

KiloKilo

Stephen Haley wrote:
These retailers are expensive - go to the source
http://sabahoceanic.com/SearchResult.aspx?CategoryID=9
They will tag them for free
Use 8x BR-C and you will get 12V 10000mah for $128
(these are 3v cells as opposed to the normal 3.7v)

These are interesting, but their voltage falls off a lot with current
and temperatu Volts/cell = 2.2 (300 ma drain, 32 F); . That's only
8.8 volts with 4 cells in series, so you'd need at least 5 in series
just to get 11 volts.

But the size and weight are sure attractive (for four cells) compared to
a 12 volt, 5 ah SLA battery: about the same height and length, but less
than half the thickness, and 6 ounces vs 60! No wonder the model
airplane people like them!

There sure is a variation in output currents for similar amphours. This
unit

Saft Lithium LS26500 [C] 3.6V. 7700mAh

is limited to 10 ma!

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

Eric Greenwell
Washington State
USA

What I wish for is a 14V, 12 AH Lithium-Polymer battery pack that comes with
a "snap-in" fixture. It would be nice to just snap in a freshly charged
battery just before a flight instead of fiddling with wires and battery
tie-downs or charging the battery in the glider. Maybe something that goes
in a 57mm instrument hole.

Bill Daniels

"Ken Kochanski (KK)" wrote in message
oups.com...
Although the technology is still pricy vs lead-acid batteries, the
power/weight/size vs cost equation is getting better. Anybody using
lithium model airplane packs bundeled to produce 12 - 14 v @3 - 6 amps
as a power source for their glider? (I have been looking at the
duralite site ... I'm sure there are others.)
http://www.duralitebatteries.com/batteries.html

KiloKilo

Lithium powered electric socks? www.cozywinters.com
williscomb

John Giddy writes:

If you use a well designed switching regulator which can boost as well
as buck, the voltage supplied to the instruments can be maintained in
the ideal range until the battery is almost completely flat, and at an
average efficiency of about 80%.

With carefull design and construction, you can get over 95% efficient
converters running from a 12v source.

AFAIK, complete discharge is not harmful to NiCd, Lithium types
etc. It is harmful to lead acid batteries.

Full dischare of a NiCd *battery* is bad news, it is OK to fully
discharge a single cell on its own though. Lead acids can be run
totally flat, but must be put on charge imediatly or they
`sulphate'. Don't know about the various Li batteries.

--
Paul Repacholi 1 Crescent Rd.,
+61 (08) 9257-1001 Kalamunda.
West Australia 6076
comp.os.vms,- The Older, Grumpier Slashdot
Raw, Cooked or Well-done, it's all half baked.
EPIC, The Architecture of the future, always has been, always will be.

Nickel Metal Hydride packs also dislike being too deeply discharged. Apart
from that they offer a lot of the benefits - High density, high current,
low temperature operation of other modern batteries. Compared to lead acid
'gel cell' types they offer a reduction in mass of 50%.

My 9Ah 14.4volt NiMh battery is 2/3 the size of a standard 7 Ah 12v gell
cell and weighs 1/2 as much.

Ian

wrote in message
...
John Giddy writes:

If you use a well designed switching regulator which can boost as well
as buck, the voltage supplied to the instruments can be maintained in
the ideal range until the battery is almost completely flat, and at an
average efficiency of about 80%.

With carefull design and construction, you can get over 95% efficient
converters running from a 12v source.

AFAIK, complete discharge is not harmful to NiCd, Lithium types
etc. It is harmful to lead acid batteries.

Full dischare of a NiCd *battery* is bad news, it is OK to fully
discharge a single cell on its own though. Lead acids can be run
totally flat, but must be put on charge imediatly or they
`sulphate'. Don't know about the various Li batteries.

--
Paul Repacholi 1 Crescent Rd.,
+61 (08) 9257-1001 Kalamunda.
West Australia 6076
comp.os.vms,- The Older, Grumpier Slashdot
Raw, Cooked or Well-done, it's all half baked.
EPIC, The Architecture of the future, always has been, always will be.

AIK, complete discharge is not harmful to NiCd, Lithium types
etc. It is harmful to lead acid batteries.

The latest designs of Lithium batteries accomodate larger discharge rates and
are becoming price efficient. But they will drop dead below a threshold level,
with no hope of salvage.

Lithium packs are designed in increments of 3.7V nominal per pack. Packs are
combined in series or in parallel to achieve desired voltage and amperage
levels.

In RC airplanes, we use a voltage cutoff device integrated with the speed
control (throttle). That cuttoff level is set at 3.0V per pack. When the
motor blips, you know the cutoff level is met and it is time to land. Go much
longer and the pack is dead.

I haven't used the Lithium batteries in cold weather yes. From what I've read
their performance does decline somewhat.

There is little risk of explosion with the latest versions of chargers and
batteries. As long as the pack is not abused, there is effectively zero chance
of fire or explosion.

I'm thinking about putting Lithium batteries in my sailplane but the price
point is not good yet on 12-14V, 7AH systems.



Jim Vincent
N483SZ
illspam

tango4 wrote:
Nickel Metal Hydride packs also dislike being too deeply discharged. Apart
from that they offer a lot of the benefits - High density, high current,
low temperature operation of other modern batteries. Compared to lead acid
'gel cell' types they offer a reduction in mass of 50%.

My 9Ah 14.4volt NiMh battery is 2/3 the size of a standard 7 Ah 12v gell
cell and weighs 1/2 as much.

I'm looking for ways to fit more AH into standard glider battery boxes,
so people can add a transponder without decreasing the battery run time
or going to the trouble of installing another battery box. For example,
going from a 7 AH battery to a 10 AH pack might achieve this,
particularly if it's a 14 volt pack instead of a 12 volt pack.

What battery (brand and part numbers, if you can) and charger do you
use, and where can we get them?

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

Eric Greenwell
Washington State
USA