PDA power consumption

[AK]

Can anyone tell me what a typical power consumption for a PDA is? I
got ipaq 3950, but I guess they all must all be close.

[Darryl Ramm]

On Feb 21, 4:00 pm, AK > wrote:
> Can anyone tell me what a typical power consumption for a PDA is? I
> got ipaq 3950, but I guess they all must all be close.

Typically it is greater than zero amps and less than 1 amp :-) I bet
that did not help much.

It depends significantly whether you are charging the battery, whether
the screen backlight is on, and total power drawn will of course
depend on whether you have an extended battery pack or not. Worse case
the power consumed can be even greater than those pesky transponders
everybody worries about. And a PDA can draw current even when turned
off. For a iPAQ 4700/4705 you can see numbers ranging from 9 mA (PDA
of and fully charged), 440 mA (*OFF* and charging) to 610 mA worse
case. These are @ 12 volts equivalent, i.e. roughly the actual current
you should see drawn from your glider battery. How long the PDA draws
the maximum current will depend on how discharged its batteries are.
I'm too lazy to try to reproduce it here but there is a full table of
power draw for the iPAQ 4700 in my battery presentation at
http://www.darrylramm.com/glider-batteries.

If you are trying to work out how long your glider battery can power a
PDA for, don't forget the capacity of the battery can depend
significantly on the total simultaneous current drawn from it, and the
temperature, see the discharge curves in the battery presentation
above.

If you are working out how large a fuse or breaker to put in the
charging circuit, several amps will do. It does not really matter as
you are mostly protecting the wiring. Avoid small (1A) breakers as
they waste power. You may not need a breaker or fuse if the 12 volt
powered charging circuit has its own protection.

Cheers


Darryl

[AK]

On Feb 21, 9:06*pm, Darryl Ramm > wrote:
> On Feb 21, 4:00 pm, AK > wrote:
>
> > Can anyone tell me what a typical power consumption for a PDA is? I
> > got ipaq 3950, but I guess they all must all be close.
>
> Typically it is greater than zero amps and less than 1 amp :-) I bet
> that did not help much.
>
> It depends significantly whether you are charging the battery, whether
> the screen backlight is on, and total power drawn will of course
> depend on whether you have an extended battery pack or not. Worse case
> the power consumed can be even greater than those pesky transponders
> everybody worries about. And a PDA can draw current even when turned
> off. For a iPAQ 4700/4705 you can see numbers ranging from 9 mA (PDA
> of and fully charged), 440 mA (*OFF* and charging) to 610 mA worse
> case. These are @ 12 volts equivalent, i.e. roughly the actual current
> you should see drawn from your glider battery. How long the PDA draws
> the maximum current will depend on how discharged its batteries are.
> I'm too lazy to try to reproduce it here but there is a full table of
> power draw for the iPAQ 4700 in my battery presentation athttp://www.darrylramm.com/glider-batteries.
>
> If you are trying to work out how long your glider battery can power a
> PDA for, don't forget the capacity of the battery can depend
> significantly on the total simultaneous current drawn from it, and the
> temperature, see the discharge curves in the battery presentation
> above.
>
> If you are working out how large a fuse or breaker to put in the
> charging circuit, several amps will do. It does not really matter as
> you are mostly protecting the wiring. Avoid small (1A) breakers as
> they waste power. You may not need a breaker or fuse if the 12 volt
> powered charging circuit has its own protection.
>
> Cheers
>
> Darryl

I am trying to figure out what else I can have on the same battery as
PDA. Other equipment draws 600 mA with spikes to 1.7 A when
transmitting.

[Darryl Ramm]

On Feb 21, 6:25 pm, AK > wrote:
> On Feb 21, 9:06 pm, Darryl Ramm > wrote:
>
>
>
> > On Feb 21, 4:00 pm, AK > wrote:
>
> > > Can anyone tell me what a typical power consumption for a PDA is? I
> > > got ipaq 3950, but I guess they all must all be close.
>
> > Typically it is greater than zero amps and less than 1 amp :-) I bet
> > that did not help much.
>
> > It depends significantly whether you are charging the battery, whether
> > the screen backlight is on, and total power drawn will of course
> > depend on whether you have an extended battery pack or not. Worse case
> > the power consumed can be even greater than those pesky transponders
> > everybody worries about. And a PDA can draw current even when turned
> > off. For a iPAQ 4700/4705 you can see numbers ranging from 9 mA (PDA
> > of and fully charged), 440 mA (*OFF* and charging) to 610 mA worse
> > case. These are @ 12 volts equivalent, i.e. roughly the actual current
> > you should see drawn from your glider battery. How long the PDA draws
> > the maximum current will depend on how discharged its batteries are.
> > I'm too lazy to try to reproduce it here but there is a full table of
> > power draw for the iPAQ 4700 in my battery presentation athttp://www.darrylramm.com/glider-batteries.
>
> > If you are trying to work out how long your glider battery can power a
> > PDA for, don't forget the capacity of the battery can depend
> > significantly on the total simultaneous current drawn from it, and the
> > temperature, see the discharge curves in the battery presentation
> > above.
>
> > If you are working out how large a fuse or breaker to put in the
> > charging circuit, several amps will do. It does not really matter as
> > you are mostly protecting the wiring. Avoid small (1A) breakers as
> > they waste power. You may not need a breaker or fuse if the 12 volt
> > powered charging circuit has its own protection.
>
> > Cheers
>
> > Darryl
>
> I am trying to figure out what else I can have on the same battery as
> PDA. Other equipment draws 600 mA with spikes to 1.7 A when
> transmitting.

Typical sealed lead acid batteries will easilly be able to provide
power during these current spikes, and you would have awfully thin
wiring for this to be an issue for wiring. So if this is on a common
circuit breaker or fuse for this load make sure it is at least 3A,
maybe more and you are set. If there is only one fuse or breaker make
sure it is right at the battery, preferably mounted on the battery in
a way the leads to the breaker cannot ever short circuit even with
significant force applied. I'd make that breaker 5A usually.

Is the spike caused by radio transmission? For calculating power
consumption and battery life for things like radios typically assume a
transmition/reception ratio of a few percent unless you something more
accurate and just cheat by fudging battery capacity at this number
based on this percent between the battery capacity at the receive and
transmit current draws. This is only an issue with small batteries,
and not usually significant in gliders. But might be nice to have an
idea how long you battery runs with a stuck on microphone, or a
ballpark worst case battery life if you land out and are trying to
transmit a lot.

Darryl

[ZZ]

AK wrote:
> Can anyone tell me what a typical power consumption for a PDA is? I
> got ipaq 3950, but I guess they all must all be close.


Hi AK,

I have carefully measured the current draw of each piece of equipment on
my battery in my ASW20. A few things to keep in mind are...

1. My PDA is a HP iPAQ model 2215 with a standard battery, not the
higher AH battery that is available.
2. The PDA battery is being charged by the 5 VDC tap from my Cambridge 302A
3. I have a Cambridge 303 talking to the 302A.
4. I am using a 14 VDC battery.

The measured current draws are...

Cambridge 302A/303 with PDA disconnected: 80ma.
Cambridge 302A/303 with PDA connected and turned ON: 280ma.

I seems that my 2215 requires about a 200ma charging current.

I hope this helps.

Paul
ZZ

[[email protected]]

On Feb 22, 8:53*pm, ZZ > wrote:
> AK wrote:
> > Can anyone tell me what a typical power consumption for a PDA is? I
> > got ipaq 3950, but I guess they all must all be close.
>
> Hi AK,
>
> I have carefully measured the current draw of each piece of equipment on
> my battery in my ASW20. A few things to keep in mind are...
>
> 1. My PDA is a HP iPAQ model 2215 with a standard battery, not the
> higher AH battery that is available.
> 2. The PDA battery is being charged by the 5 VDC tap from my Cambridge 302A
> 3. I have a Cambridge 303 talking to the 302A.
> 4. I am using a 14 VDC battery.
>
> The measured current draws are...
>
> * * * * * * * * Cambridge 302A/303 with PDA disconnected: *80ma.
> * * * * * * * * Cambridge 302A/303 with PDA connected and turned ON: 280ma.
>
> I seems that my 2215 requires about a 200ma charging current.
>
> I hope this helps.
>
> Paul
> ZZ

Paul,

What does your PDA draw when the battery is topped off? Have you
compared the draw during charge vs. after charge? Once the charge
circuit is shut down (battery full), the current draw should lessen.

On my Dell Axim, the power button is red when charging, and green when
the battery is topped off. I haven't measured the current during
charge yet, but I bet it'll be a tapered charge, meaning the current
will lessen as the battery gets closer to being topped off. Without a
charge "indicator", it might be hard to tell just what the PDA
requires to run without the extra current required to charge the
battery.

I would imagine that most folks will make sure their PDA is fully
charged before powering it up from the ship's power supply. That's
something I will make sure of since I'm flying with only a 7ah battery
on board.


Dave

[Henryk Birecki]

You have to be a bit careful when talking about PDAs power
consumption. The numbers like 200mA.. can be misleading. Yes it is a
very good idea to top off the battery prior to using PDA in a glider
because this is this much less charge that supply has to provide. Once
the battery is charged, all power supplied to PDA is being consumed
for PDA operation, battery is "off" unless supply voltage drops.
Having said that, PDAs do not consume power in a steady mode. It
depends what they are doing. Few years ago I was playing with couple
of them measuring supply currents. I do not have the data, so I cannot
give you actual numbers but current draw spikes went well above
1000mA. In some cases this may be a problem if your main battery is
nearing end of capacity.

The best thing you can do when powering a PDA from main glider battery
is to use an efficient switching DC to DC converter rather than a
"foot warmer" linear one. Modern switching converters are nearly 90%
efficient, so if a PDA requires 1000mA and you are using a 12V battery
the battery current is 5/12/0.9*1000mA = 460mA. A "poor" switching
converter is 75-80% efficient.

Cheers,
Henryk Birecki

wrote:

>On Feb 22, 8:53*pm, ZZ > wrote:
>> AK wrote:
>> > Can anyone tell me what a typical power consumption for a PDA is? I
>> > got ipaq 3950, but I guess they all must all be close.
>>
>> Hi AK,
>>
>> I have carefully measured the current draw of each piece of equipment on
>> my battery in my ASW20. A few things to keep in mind are...
>>
>> 1. My PDA is a HP iPAQ model 2215 with a standard battery, not the
>> higher AH battery that is available.
>> 2. The PDA battery is being charged by the 5 VDC tap from my Cambridge 302A
>> 3. I have a Cambridge 303 talking to the 302A.
>> 4. I am using a 14 VDC battery.
>>
>> The measured current draws are...
>>
>> * * * * * * * * Cambridge 302A/303 with PDA disconnected: *80ma.
>> * * * * * * * * Cambridge 302A/303 with PDA connected and turned ON: 280ma.
>>
>> I seems that my 2215 requires about a 200ma charging current.
>>
>> I hope this helps.
>>
>> Paul
>> ZZ
>
>Paul,
>
>What does your PDA draw when the battery is topped off? Have you
>compared the draw during charge vs. after charge? Once the charge
>circuit is shut down (battery full), the current draw should lessen.
>
>On my Dell Axim, the power button is red when charging, and green when
>the battery is topped off. I haven't measured the current during
>charge yet, but I bet it'll be a tapered charge, meaning the current
>will lessen as the battery gets closer to being topped off. Without a
>charge "indicator", it might be hard to tell just what the PDA
>requires to run without the extra current required to charge the
>battery.
>
>I would imagine that most folks will make sure their PDA is fully
>charged before powering it up from the ship's power supply. That's
>something I will make sure of since I'm flying with only a 7ah battery
>on board.
>
>
>Dave

[[email protected]]

On Feb 21, 7:00 pm, AK > wrote:
> Can anyone tell me what a typical power consumption for a PDA is? I
> got ipaq 3950, but I guess they all must all be close.

Thanks all for the answers below. I never thought of
it before, but maybe finally a good use for PDAs:
Use a pair as electric foot-warmers !
See ya, Dave "YO electric"

[ZZ]

wrote:
> On Feb 22, 8:53 pm, ZZ > wrote:
>> AK wrote:
>>> Can anyone tell me what a typical power consumption for a PDA is? I
>>> got ipaq 3950, but I guess they all must all be close.
>> Hi AK,
>>
>> I have carefully measured the current draw of each piece of equipment on
>> my battery in my ASW20. A few things to keep in mind are...
>>
>> 1. My PDA is a HP iPAQ model 2215 with a standard battery, not the
>> higher AH battery that is available.
>> 2. The PDA battery is being charged by the 5 VDC tap from my Cambridge 302A
>> 3. I have a Cambridge 303 talking to the 302A.
>> 4. I am using a 14 VDC battery.
>>
>> The measured current draws are...
>>
>> Cambridge 302A/303 with PDA disconnected: 80ma.
>> Cambridge 302A/303 with PDA connected and turned ON: 280ma.
>>
>> I seems that my 2215 requires about a 200ma charging current.
>>
>> I hope this helps.
>>
>> Paul
>> ZZ
>
> Paul,
>
> What does your PDA draw when the battery is topped off? Have you
> compared the draw during charge vs. after charge? Once the charge
> circuit is shut down (battery full), the current draw should lessen.
>
> On my Dell Axim, the power button is red when charging, and green when
> the battery is topped off. I haven't measured the current during
> charge yet, but I bet it'll be a tapered charge, meaning the current
> will lessen as the battery gets closer to being topped off. Without a
> charge "indicator", it might be hard to tell just what the PDA
> requires to run without the extra current required to charge the
> battery.
>
> I would imagine that most folks will make sure their PDA is fully
> charged before powering it up from the ship's power supply. That's
> something I will make sure of since I'm flying with only a 7ah battery
> on board.
>
>
> Dave


Dave

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.

Paul
ZZ

[Eric Greenwell]

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

[Bill Daniels]

"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.

[Eric Greenwell]

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

[Bill Daniels]

"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.

[Eric Greenwell]

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

[Michael Huber]

"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

[Bill Daniels]

"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?

[Eric Greenwell]

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

[Bill Daniels]

"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=COakjvKZ3pECFRI0awodDGUYeQ

Bill D

[Eric Greenwell]

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=COakjvKZ3pECFRI0awodDGUYeQ

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

[Bill Daniels]

"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=COakjvKZ3pECFRI0awodDGUYeQ
>
> 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