PDA power consumption

"Eric Greenwell" wrote in message
news:ja3wj.4512$O64.3149@trndny03...
ZZ wrote:

I agree. I usually install my PDA in the glider either fully charged or
nearly so. That's why I said 280ma minus 80ma is ABOUT 200ma.

Knowing this and the approximate draw by other equipment in the glider
should get me close enough to properly match a battery pack to expected
flight time.

It's more about "big enough", rather than "matching". Unless it involves
serious dollars or effort, put in one that's enough for possible future
additions, like a transponder and one of those brighter, panel-mounted
screens that are available now, and then make sure it's big enough to run
everything for serveral flights without charging. Need a 7 ah battery but
got room for an 18 ah unit? Go for it!

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Yes, Eric. But keep an eye on the maximum weight of the "non-flying parts".
A heavy lead acid 18AH battery might put some gliders over that limit.

Bill Daniels wrote:
"Eric Greenwell" wrote in message
news:ja3wj.4512$O64.3149@trndny03...
ZZ wrote:

I agree. I usually install my PDA in the glider either fully charged or
nearly so. That's why I said 280ma minus 80ma is ABOUT 200ma.

Knowing this and the approximate draw by other equipment in the glider
should get me close enough to properly match a battery pack to expected
flight time.
It's more about "big enough", rather than "matching". Unless it involves
serious dollars or effort, put in one that's enough for possible future
additions, like a transponder and one of those brighter, panel-mounted
screens that are available now, and then make sure it's big enough to run
everything for serveral flights without charging. Need a 7 ah battery but
got room for an 18 ah unit? Go for it!

Yes, Eric. But keep an eye on the maximum weight of the "non-flying parts".
A heavy lead acid 18AH battery might put some gliders over that limit.

Proper weight and balance is assumed, so that would fall under the
"serious dollars or effort" caveat; e.g., buying a lighter parachute or
dieting off the 8 pound difference between a 7 ah and 18 ah battery!

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

"Eric Greenwell" wrote in message
news:0W6wj.4526$O64.2414@trndny03...
Bill Daniels wrote:
"Eric Greenwell" wrote in message
news:ja3wj.4512$O64.3149@trndny03...
ZZ wrote:

I agree. I usually install my PDA in the glider either fully charged or
nearly so. That's why I said 280ma minus 80ma is ABOUT 200ma.

Knowing this and the approximate draw by other equipment in the glider
should get me close enough to properly match a battery pack to expected
flight time.
It's more about "big enough", rather than "matching". Unless it involves
serious dollars or effort, put in one that's enough for possible future
additions, like a transponder and one of those brighter, panel-mounted
screens that are available now, and then make sure it's big enough to
run everything for serveral flights without charging. Need a 7 ah
battery but got room for an 18 ah unit? Go for it!

Yes, Eric. But keep an eye on the maximum weight of the "non-flying
parts". A heavy lead acid 18AH battery might put some gliders over that
limit.

Proper weight and balance is assumed, so that would fall under the
"serious dollars or effort" caveat; e.g., buying a lighter parachute or
dieting off the 8 pound difference between a 7 ah and 18 ah battery!

--
Eric Greenwell - Washington State, USA

All I asid was "keep an eye on non-flying parts weight". I'm sure you
aren't advocating ignoring it.

Well, In my case, getting below the Max Wt for non-flying parts required
removing two 12AH batteries and replacing them with one 7AH and replacing a
steel O2 bottle with an aluminum one and the heavy demand O2 regulator with
a light MH one. Since the steel O2 bottle was behind the wing, CG
considerations forced me to mount the 7AH on the floor ahead of the panel
instead of the usual position next to the wheel box. That was about $1500
and a months work. I already had a new, light parachute and I'm still
working on the diet.

The net result was reducing the fuselage weight by 22 Lbs. I'm just below
the allowed weight so adding an 18AH Lead Acid is not possible without
removing 18 pounds somewhere else. More likely is to make a 8 or 20 cell
pack using new LiFePO4 cells from A123 Systems which would provide 22AH at
about the same weight and size as the 7AH lead battery.

Bill D

I'd like to carry more drinking water and a more robust landout kit.
Everything is a tradeoff.

Bill Daniels wrote:

All I asid was "keep an eye on non-flying parts weight". I'm sure you
aren't advocating ignoring it.

Definitely not, but I have been assuming that pilots will ensure their
weight and balance is correct when they mount new batteries or other
equipment, and that they know "weight" means all weight limitations in
the manual, not just total weight.


Well, In my case, getting below the Max Wt for non-flying parts required
removing two 12AH batteries and replacing them with one 7AH and replacing a
steel O2 bottle with an aluminum one and the heavy demand O2 regulator with
a light MH one. Since the steel O2 bottle was behind the wing, CG
considerations forced me to mount the 7AH on the floor ahead of the panel
instead of the usual position next to the wheel box. That was about $1500
and a months work. I already had a new, light parachute and I'm still
working on the diet.

This work definitely qualifies for the "serious dollars or effort" award.

The net result was reducing the fuselage weight by 22 Lbs. I'm just below
the allowed weight so adding an 18AH Lead Acid is not possible without
removing 18 pounds somewhere else.

It's not quite that bad - 18 AH lead acid batteries are 12 to 13 pounds,
not 18, and you would be replacing a 7 AH battery of 5 pounds, for a net
change of 8 pounds. Perhaps you are including a battery container and
other mounting required.

More likely is to make a 8 or 20 cell
pack using new LiFePO4 cells from A123 Systems which would provide 22AH at
about the same weight and size as the 7AH lead battery.

These are quite interesting cells that I was not aware of previously.
Which units are you considering? The 26650 units, with 2.3 AH, would
take about 30 cells to make a ~ 12 volt, 22 AH battery, but I couldn't
find spec sheets for any other cells.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

"Eric Greenwell" wrote:

These are quite interesting cells that I was not aware of previously.
Which units are you considering? The 26650 units, with 2.3 AH, would take
about 30 cells to make a ~ 12 volt, 22 AH battery, but I couldn't find
spec sheets for any other cells.

You need a 4s configuration to get 14,4V fully charged with A123 cells,
28cells in 4s/7p give 16Ah. A 20 cells pack can be arranged in 4s/5p to have
almost the same dimensions as a 12V/7Ah SLA battery and give 11,5Ah.

Michael

"Eric Greenwell" wrote in message
news:zgkwj.211$tH.167@trndny01...
Bill Daniels wrote:

More likely is to make a 8 or 20 cell pack using new LiFePO4 cells from
A123 Systems which would provide 22AH at about the same weight and size
as the 7AH lead battery.

These are quite interesting cells that I was not aware of previously.
Which units are you considering? The 26650 units, with 2.3 AH, would take
about 30 cells to make a ~ 12 volt, 22 AH battery, but I couldn't find
spec sheets for any other cells.

There are two cell formats now available. One is the 2.3 AH used in a
variety of devices including 36V DeWalt power tools. Each DeWalt 36V power
pack contains 10 cells and are available on eBay - the cheapest way to buy
them.

The other cell is for electric vehicles at 10AH. Most gliders would only
need 4 cells in series.

The key to the A123Systems LiFePO4 chemestry is its extreme resistance to
thermal runaway, the extremely high rates of charge and discharge and the
very long life exceeding 5000 charge cycles. A123Systems, a MIT spinoff, is
in the lead to provide batteries for the GM Volt Hybrid.

But, nothing stands still. A Dr. Yi Che, a Stanford researcher announced
back in November that he had adapted silicon nanowires to the Anode which
"could" increase the cells capacity by 10x. MIT Technology Review Magazine
aknowledged Dr. Yi's work but harrumphed back saying that Dr. Yi's results
would "only" increase the capacity 3x until simular work was done on the
Cathode. Tech Rev didn't seem pessimistic about that possibility.

So, it appears that we will soon have cells with 10x the already very high
capacity of the A123 cells that can, given a sufficiently robust charger,
recharge in 10 minutes and discharge at a high enough rate to set world
reconds in an electric motorcycle dragster. (Google: "Killacycle")

Anybody want to speculate what could be done with that kind of battery?

Bill Daniels wrote:
"Eric Greenwell" wrote in message
news:zgkwj.211$tH.167@trndny01...
Bill Daniels wrote:

More likely is to make a 8 or 20 cell pack using new LiFePO4 cells from
A123 Systems which would provide 22AH at about the same weight and size
as the 7AH lead battery.
These are quite interesting cells that I was not aware of previously.
Which units are you considering? The 26650 units, with 2.3 AH, would take
about 30 cells to make a ~ 12 volt, 22 AH battery, but I couldn't find
spec sheets for any other cells.

There are two cell formats now available. One is the 2.3 AH used in a
variety of devices including 36V DeWalt power tools. Each DeWalt 36V power
pack contains 10 cells and are available on eBay - the cheapest way to buy
them.

The other cell is for electric vehicles at 10AH. Most gliders would only
need 4 cells in series.

Where can I get datasheets, and are there any sources for the 10 AH
cells? I'm intrigued by the low temperature performance and the engery
density. Even though I have plenty of capacity in my glider. these
features would be an aid in winter wave flying, and unassisted safaris.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

"Eric Greenwell" wrote in message
news:51owj.2307$A93.113@trndny08...
Bill Daniels wrote:
"Eric Greenwell" wrote in message
news:zgkwj.211$tH.167@trndny01...
Bill Daniels wrote:

More likely is to make a 8 or 20 cell pack using new LiFePO4 cells
from A123 Systems which would provide 22AH at about the same weight and
size as the 7AH lead battery.
These are quite interesting cells that I was not aware of previously.
Which units are you considering? The 26650 units, with 2.3 AH, would
take about 30 cells to make a ~ 12 volt, 22 AH battery, but I couldn't
find spec sheets for any other cells.

There are two cell formats now available. One is the 2.3 AH used in a
variety of devices including 36V DeWalt power tools. Each DeWalt 36V
power pack contains 10 cells and are available on eBay - the cheapest way
to buy them.

The other cell is for electric vehicles at 10AH. Most gliders would only
need 4 cells in series.

Where can I get datasheets, and are there any sources for the 10 AH cells?
I'm intrigued by the low temperature performance and the engery density.
Even though I have plenty of capacity in my glider. these features would
be an aid in winter wave flying, and unassisted safaris.

Google didn't turn up the A123 cell but the 10 AH cell specification seems
to be converging around a standard for electric vehicle use.

See: http://www.lifebatt.com/?gclid=COakj...FRI0awodDGUYeQ

Bill D

Bill Daniels wrote:

The other cell is for electric vehicles at 10AH. Most gliders would only
need 4 cells in series.
Where can I get datasheets, and are there any sources for the 10 AH cells?
I'm intrigued by the low temperature performance and the engery density.
Even though I have plenty of capacity in my glider. these features would
be an aid in winter wave flying, and unassisted safaris.

Google didn't turn up the A123 cell but the 10 AH cell specification seems
to be converging around a standard for electric vehicle use.

See: http://www.lifebatt.com/?gclid=COakj...FRI0awodDGUYeQ

Yikes! To replace one of my $45, 18 AH batteries would cost about
$600-$900, depending on how I did it. Since my needs aren't very
demanding, I'll wait till the price comes down some more. At this time,
Strobl solar panels for the same money would be a better choice for me.
STill, a pilot with real weight, space, and temperature issues should
find them interesting, despite the cost. I am glad to see safer Li cells
appearing.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

"Eric Greenwell" wrote in message
news:JYqwj.1891$RQ3.434@trndny05...
Bill Daniels wrote:

The other cell is for electric vehicles at 10AH. Most gliders would
only need 4 cells in series.
Where can I get datasheets, and are there any sources for the 10 AH
cells? I'm intrigued by the low temperature performance and the engery
density. Even though I have plenty of capacity in my glider. these
features would be an aid in winter wave flying, and unassisted safaris.

Google didn't turn up the A123 cell but the 10 AH cell specification
seems to be converging around a standard for electric vehicle use.

See: http://www.lifebatt.com/?gclid=COakj...FRI0awodDGUYeQ

Yikes! To replace one of my $45, 18 AH batteries would cost about
$600-$900, depending on how I did it. Since my needs aren't very
demanding, I'll wait till the price comes down some more. At this time,
Strobl solar panels for the same money would be a better choice for me.
STill, a pilot with real weight, space, and temperature issues should find
them interesting, despite the cost. I am glad to see safer Li cells
appearing.

Yeah, price is still the showstopper.

However, if these are going to be used in electric cars, the price has to
come WAY down - maybe below lead acid. Several interested parties have said
the manufacturing process scales well so there are large economies of scale.
Maybe next year.

In the meantime, the DeWalt 36 volt 10 cell power packs can bought for about
$150 a pair on eBay.

Bill D