Wireless iPods

> That said, I think hotspot-compatible audio streaming would be key to
> making a wireless music device like an iPod successful, at least in
> the medium term, especially since the additional bandwidth provided
> by wireless FireWire is not necesary.

Yessbutt....

The most common complaint I've heard about iPods (including the one I've
just ordered from Small Dog; $325 for a third-generation 40GB, complete with
case and remote-control headphones, two things Apple no longer include in
the box, seemed too good a deal to pass up, and it's currently on its way to
me, having left Doraville, somewhere in Georgia, this morning at 2:47 ‹ I
love online parcel tracking!) is that the battery life is poor. Sure, Apple
advertise 8 hours, but I'm told that four to six is more realistic, and I've
also hear that the average iPod battery dies terminally after a year or two.
I understand that the newer fourth-generation iPods get up to 12 hours, but
long-term battery life still isn't known, obviously.

On the other hand, I do know that AirPort is one of my Powerbook's larger
battery drains. So the problem then would seem to be one of battery life
when you have a weak battery and, in addition to an existing load, the
further battery hit of a wireless connection. Yes, I realise that most of
the time the iPod would only be receiving; this would drop the power
requirement somewhat, but even so, I still think that Apple will need to
perfect their battery technology before they start increasing the battery
load.

Of course, they could simply require that using wireless streaming be done
when the iPod is plugged in, but this would rather defeat the object, one
can't help but feel.

Steve

On 9/23/04 12:17 PM, "Big Steve" <bigstevemacearthlink.net> wrote:
> Sure, Apple advertise 8 hours, but I'm told that four to six is more
> realistic, and I've also hear that the average iPod battery dies terminally
> after a year or two.

Don't believe all the "bad news" you hear ;-)

Battery life is dependent on a lot of factors. If you skip songs constantly,
the iPod has to spend a lot of time spinning up its hard drive to fill its
RAM buffer with music, so your battery life will suffer. Similarly, if
you've set the iPod's backlight to be on constantly, that takes juice. On
the other hand, if you tend to choose a playlist and just listen, you'll get
much better battery life -- I regularly got 8+ hours on my 3G iPod, and have
seen 13 hours from my 4G model.

As for the overall lifespan of the iPod battery, it again depends on how you
use it and how much you use it. Lithium Ion batteries generally have a
lifespan of 300-500 "charge cycles":

    A charge cycle means using all of the battery¹s power, but that
    doesn¹t necessarily mean a single charge. For instance, you could
    listen to your iPod for a few hours one day, using half its power,
    and then recharge it fully. If you did the same thing the next day,
    it would count as one charge cycle, not two, so you may take
    several days to complete a cycle. Each time you complete a charge
    cycle, it diminishes battery capacity slightly, but you can put
    both notebook and iPod batteries through many charge cycles before
    they will only hold 80% of original battery capacity.

<http://www.apple.com/batteries/>

So if you run your iPod battery down every day and then recharge it, you'll
likely need a new battery after a year or year and a half. However, if you
only listen a few hours a day, your battery will last much longer, although
the nature of the battery means that its playback time will gradually
decrease. I know people with first-generation iPods that still get 6-7 hours
of playback time from a single charge, which is fairly impressive
considering that these iPods are now three years old.

More info on iPod batteries here:

<http://www.ipodbatteryfaq.com/>

--
-------------------------
Dan Frakes
Reviews Editor Playlist
<http://playlistmag.com/>
-------------------------

>> That said, I think hotspot-compatible audio streaming would be key to
>> making a wireless music device like an iPod successful, at least in
>> the medium term, especially since the additional bandwidth provided
>> by wireless FireWire is not necesary.

To add to my previous comments (I can only be that profoundly insightful for
so long), I can see another potential problem with making an iPod
compatible with hotspots.

Assuming that we're talking about public hotspots, then we are going to have
to find some way of limiting access ‹ presumably by means of passwords. And
that means some way of inputting a password into the device. Consequently,
we have to have some kind of interface which will enable this. Right now,
I'm hard pushed to think of a way that the iPod could handle any real kind
of alphanumeric input, other than some kind of rather convoluted messing
around with the scrollwheel. The alternative would be to put a keyboard on
it. Let's seeŠLCD screen, hard disc, keyboard, firewire, airportŠhmmmŠ I
already have that device. It's called a Powerbook.

I suppose an alternative would be a small numeric keypad, but then we're
looking either at the highly unpleasant task of inputting text via number
keys, the main reason why I very rarely send text messages via my phone (or
at least didn't until I got Bluetooth in my phone and Palm), or using only
numeric passcodes. Another alternative would be to have a mechanism for
setting up an account with the hotspot provider via the user's home
computer, then installing this account's user name and password information
along with music data during an iPod sync.

I would very much like to see the latter introduced. Among many features
which have given the iPod quite rampant market share, one of the most
important is its elegance. It's quite delightfully minimalist, even though
it does an awful lot. I realise that Apple are just the kind of company who
could figure out a way of dealing with this issue, but right now I can't
think of anything beyond the two I've just suggested.

I suppose that's why I'm a flight instructor, not an Apple designer.

Steve

On 24/9/2004 7:17 AM, "Big Steve" <bigstevemacearthlink.net> spake thus:

> I still think that Apple will need to perfect their battery technology
> before they start increasing the battery load.

I can see that Apple is going to end up in the same bind as the cell phone
manufacturers. Battery technology has failed to keep pace with the
increasing power demands of mobile handsets (cameras, video, MP3 players,
radios, etc., etc., etc.). I see that Kyocera has even just released a
mobile with a 1" 1.5 GB hard drive. It's getting to the point that many
modern cell phones have a very short battery life, unless you turn
everything off, and on some phone, you can't even have everything turned on
at the same time because the battery just can't supply enough power.

I can't really see the situation getting any better unless someone suddenly
figures out how to make small, efficient, cheap and powerful fuel cells, but
at least the good news is that Apple isn't the only company that will be
pushing for advances in this area. The more companies yell and scream, the
more likely it is that someone will try to come up with a solution :)

--
Nigel Stanger, mailto:nstangerinfoscience.otago.ac.nz
Dept. of Information Science, http://divcom.otago.ac.nz/infosci/
University of Otago, Dunedin, NEW ZEALAND. XNS: =Nigel Stanger

> Another alternative would be to have a mechanism for
> setting up an account with the hotspot provider via the user's home
> computer, then installing this account's user name and
> password information along with music data during an iPod sync.

Yes, being able to create Locations for the iPod using your computer
(probably using new window in iTunes as the interface) would be essential.
You would use this to put in the information for your own base station or
that of a friend. Configuration for major hotspot providers like T-Mobile
HotSpot would probably be a menu option.

Entering a username and password would not be a big deal using the existing
iPod interface. You regularly whip through the alphabet using the wheel to
select playlists, albums, tracks, etc. It would be like entering your name
in a arcade or console video game. For each letter, you would scroll to find
it, click on the right to enter it, click on the left to backspace, click up
or down when you're finished in the field. If you often used the same
username, there could be an autofill option (no autofill for the password
because *of course* you don't use the same password for different networks,
right?) It's still a bit annoying but you would only have to do it when you
encountered a new wireless network. Once you did it, the information for
that Location would be saved.

The real problem is dealing with the myriad authentication methods used by
various people providing access. Many use web pages for the authentication
and while a wireless iPod may use HTTP as the transport for sending
authentication information, most likely you could not put even a minimal web
browser on an iPod and have it do what it needs to do. As long as there's
not a widely adopted standard for commercial and non-commercial access point
authentication, I don't know this is resolved.

Some wireless providers may not *want* wireless iPods using their network.
They would probably be streaming 128Kbps and that can add up fast. 10 people
listening to such streams equals 1280Kbps that's most of an access point's
uplink if it's on a 1.5Mbps DSL line. The iPod would have a sizable buffer
but if a laptop user on the connection started downloading sizable (e.g.
Windows XP Service Pack 2), it could cause problems for the iPod listeners.

--On Friday, September 24, 2004 8:00 AM -0700 Dan Frakes <DanFrakes.org>
wrote:

> Battery life is dependent on a lot of factors. If you skip songs
> constantly, the iPod has to spend a lot of time spinning up its hard
> drive to fill its RAM buffer with music, so your battery life will
> suffer. Similarly, if you've set the iPod's backlight to be on
> constantly, that takes juice. On the other hand, if you tend to choose a
> playlist and just listen, you'll get much better battery life -- I
> regularly got 8+ hours on my 3G iPod, and have seen 13 hours from my 4G
> model.

I think the alarm setting affects battery life too. I got a fair extension
of battery life by turning off alarms from the calendar.

[I use the iPod as an alarm clock, and because it turns on automatically and never turns off, it's a great way to drain the battery without realizing. -Adam]

On the topic of wireless iPods -- it would indeed be cool to stream music
down from a hotspot, but wouldn't it be even cooler to stream it back up?
Walk into a coffeshop, your ipod shows up on other's players via Rendezvous
and the hotspot network and people try to listen. You approve up to x
number of people listening and bang, you're a pirate radio station.

Now that would be neato.

Kevin

Wilcox, Curtis wrote:

>The real problem is dealing with the myriad authentication methods used by
>various people providing access. Many use web pages for the authentication
>and while a wireless iPod may use HTTP as the transport for sending
>authentication information, most likely you could not put even a minimal web
>browser on an iPod and have it do what it needs to do. As long as there's
>not a widely adopted standard for commercial and non-commercial access point
>authentication, I don't know this is resolved.
>
>
802.1X is just the ticket for this. The "X" isn't a placeholder, that's
the proper name for the standard. Basically it builds user
authentication into the network hardware layer; you have to authenticate
as yourself, and be authorized by the network provider, *before* you get
an IP number. It's a very cool idea, but has to be supported by the OS,
the NIC, switch (or access point), and DHCP server. (It's already
supported by OS X and some species of newer Apple hardware, but I don't
know which of the latter. IIRC, Windows XP has 802.1X, but Windows 2000
and prior do not.)

Using 802.1X in an embedded device like the iPod would be a very
pushing-an-existing-but-not-well-known-standard Apple thing to do, IMO.
If I were to read the tea leaves, they'd introduce such a device with
backing from a major hotspot retailer, like T-Mobile. (Not that I know
anything, I'm just talking here.)

http://www.wi-fiplanet.com/tutorials/article.php/1041171

The wireless network here requires MAC registration, with all the access
points consulting a RADIUS database for client MACs. I think 802.1X is
our future, but I don't think we're at the OS support tipping point yet.

--
Andrew Laurence
atlaurenuci.edu

But, the iPod does have a great input device - the scroll wheel. Fix that
up with a display representation of a bank vault combination number lock,
and you're away! 10 right, 7 left, 18 right, 6 right, 10 left and you're in!

You can even have an alphanumeric display, if you want to allow for use of
familiar passwords.

--
Ian Eiloart
Servers Team
Sussex University ITS

Kevin Van Haaren wrote:

> On the topic of wireless iPods -- it would indeed be cool to stream music
> down from a hotspot, but wouldn't it be even cooler to stream it back up?
> Walk into a coffeshop, your ipod shows up on other's players via Rendezvous
> and the hotspot network and people try to listen. You approve up to x
> number of people listening and bang, you're a pirate radio station.
>
> Now that would be neato.

Oh, most undeniably neato ‹ especially to the intellectual-property lawyers.
While it might not necessarily be the easiest thing in the world (depending
on precisely how OpenTalk [The Technology Formerly Known As Rendezvous,
henceforth TTFKAR, thanks to the aforementioned lawyers] identifies the
pirate station) to identify the guilty party, I'm pretty certain we're
getting into some rather thorny public-performance issues with this
otherwise-spiffing idea.

Of course, the other problem is, once again, battery power. While it's true
that receiving a stream will also require battery power, it'll require less
to receive, passively, than to transmit, an active, erm, activity.

Steve

On Tue, 28 Sep 2004 06:36:57 -0700, Andrew Laurence
<atlaurenes.nacs.uci.edu> wrote:
> IIRC, Windows XP has 802.1X, but Windows 2000
> and prior do not.)

Windows 2000 Server, at least, does. I just spend a few days futzing
with a network that uses 802.1x (why? I don't know, it's a physically
discreet LAN sitting behind a NAT router, but that's how it is setup.)

> Using 802.1X in an embedded device like the iPod would be a very
> pushing-an-existing-but-not-well-known-standard Apple thing to do, IMO.

I think it would be great! Perhaps it would also lead to being able
to sync your ipod on any of your iTunes authorised machines instead of
just one.

--
 ::::== <http://2blog.kreme.com> ==::::

Broadcast is the main use I can see for iPod wireless; it seems to me
like the best capsule description of the iPod has always been "playback
circuitry wrapped around a portable storage device." If you're talking
about streaming music from your server at home, your storage device
isn't up to snuff, and it's time to improve that, instead of tacking on
more ancillary gear.

I can see some merit in a device to receive public broadcast MP3
broadcast streams, like the 'radio stations' in iTunes, but I have to
wonder what this would give that a combination of XM Satellite and
ordinary broadcast radio doesn't already have. The main thing I come up
with from the standpoint of the general public is 'listening to my own
customized feed,' which just brings us back to the point above. And of
course, there's the point made earlier in this thread that multiple
streaming customers at a hotspot has the potential to start swamping the
bandwidth.

On 9/30/04 at 10:14 AM, bigstevemacearthlink.net (Big Steve) wrote:

> Kevin Van Haaren wrote:
>
> > On the topic of wireless iPods -- it would indeed be cool to stream
> > music down from a hotspot, but wouldn't it be even cooler to stream
> > it back up? Walk into a coffeshop, your ipod shows up on other's
> > players via Rendezvous and the hotspot network and people try to
> > listen. You approve up to x number of people listening and bang,
> > you're a pirate radio station.
> >
> > Now that would be neato.

...however, this isn't the broadcast model I'd be thinking of...

> Oh, most undeniably neato — especially to the intellectual-property
> lawyers. While it might not necessarily be the easiest thing in the
> world (depending on precisely how OpenTalk [The Technology Formerly
> Known As Rendezvous, henceforth TTFKAR, thanks to the aforementioned
> lawyers] identifies the pirate station) to identify the guilty party,
> I'm pretty certain we're getting into some rather thorny
> public-performance issues with this otherwise-spiffing idea.

Aside from the legal issues, I have to think the idea of demoing music
for friends is better-served by using an FM transmitter like the iTrip;
while reception can be problematic in some locations, judging by my own
experience, it's still usable in a *lot* more areas. Your potential
soundstage becomes any place with an FM radio, which is a much broader
audience than a still fairly limited selection of hotspots.

(OK, Kevin, I admit it'd be cool to sit in the grand atrium at Union
Station and connect with other Pod-people and play around with music. :)
But Union Station's just one place; FM radios are *everywhere*.)

The big use I see for iPod wireless is something I've seen mentioned in
combination with Airport Express reviews: streaming directly from an
iPod to an Airport Express.

> Of course, the other problem is, once again, battery power. While
> it's true that receiving a stream will also require battery power,
> it'll require less to receive, passively, than to transmit, an
> active, erm, activity.

I'm no wireless tech; but from what I do understand, even streaming is a
two-way conversation, because all TCP/IP-based services are. Every so
often, the recipient has to send an acknowledgement packet so that the
sender knows it's been receiving correctly. So while the transmitter
wouldn't be pushing a lot of data while it's receiving a stream, it
certainly wouldn't be 'passive' as far as I know, and the transmitter
itself would probably stay 'hot' the whole time to send those
acknowledgement packets.

(The preceding was cribbed from my memory of a NetBITS article on
Bandwidth vs. Latency. Anyone who knows more, please feel free to
correct me. :) )

Travis Butler
tbutlermac.com

> Kevin Van Haaren wrote:
>
> > On the topic of wireless iPods -- it would indeed be cool
> to stream music
> > down from a hotspot, but wouldn't it be even cooler to
> stream it back up?
> > Walk into a coffeshop, your ipod shows up on other's
> players via Rendezvous
> > and the hotspot network and people try to listen. You
> approve up to x
> > number of people listening and bang, you're a pirate radio station.
> >
> > Now that would be neato.
>
> Oh, most undeniably neato < especially to the
> intellectual-property lawyers.
> While it might not necessarily be the easiest thing in the
> world (depending
> on precisely how OpenTalk [The Technology Formerly Known As
> Rendezvous,
> henceforth TTFKAR, thanks to the aforementioned lawyers]
> identifies the
> pirate station) to identify the guilty party, I'm pretty certain we're
> getting into some rather thorny public-performance issues with this
> otherwise-spiffing idea.

I don't think this would be substantively different than some people in the
same area sharing their playlists using iTunes on laptops. And if it wasn't
on-demand listening of tracks but instead a radio-like streamed playlist,
how would this any more of a public performance than someone cranking up
their boom box at the beach? I think as long as it remained ad hoc and
non-commercial, Kevin's idea would stay out of the legal gunsights. Of
course some lawyers are always looking for (or perhaps inventing) new
infractions so it's impossible to say definitively.

> Of course, the other problem is, once again, battery power.
> While it's true
> that receiving a stream will also require battery power,
> it'll require less
> to receive, passively, than to transmit, an active, erm, activity.

Is this true? With Wi-Fi at least, my understanding was power consumption was
not affected by sending or receiving, the card has to do both so the
consumption is fairly steady.

--On Thursday, September 30, 2004 10:14 AM -0700 Big Steve
<bigstevemacearthlink.net> wrote:

> Oh, most undeniably neato ? especially to the intellectual-property
> lawyers. While it might not necessarily be the easiest thing in the world
> (depending on precisely how OpenTalk [The Technology Formerly Known As
> Rendezvous, henceforth TTFKAR, thanks to the aforementioned lawyers]
> identifies the pirate station) to identify the guilty party, I'm pretty
> certain we're getting into some rather thorny public-performance issues
> with this otherwise-spiffing idea.
>
> Of course, the other problem is, once again, battery power. While it's
> true that receiving a stream will also require battery power, it'll
> require less to receive, passively, than to transmit, an active, erm,
> activity.

I figured it isn't too much of an expansion over how iTunes works now. I
can go to a wireless hotspot, fire up iTunes on my PowerBook and share my
music with 5 other people. The cool part with the ipod version is
portability and (eventually) quantity. I carry my iPod way more than I
carry my laptop, and I see a lot more other people with iPods than I do
using their PowerBooks (which I assume are tucked away in backpacks and
laptop bags).

Kevin

--On Friday, October 1, 2004 7:16 PM -0700 Travis Butler
<tbutlerbirch.net> wrote:

> Aside from the legal issues, I have to think the idea of demoing music
> for friends is better-served by using an FM transmitter like the iTrip;
> while reception can be problematic in some locations, judging by my own
> experience, it's still usable in a *lot* more areas. Your potential
> soundstage becomes any place with an FM radio, which is a much broader
> audience than a still fairly limited selection of hotspots.

Other than the short range of the iTrip this would work pretty well too,
although my method has the ability to limit the number of people that can
listen, where the FM broadcast method doesn't.

Somebody's solved the range issue too, here's how to extend the range of an
iTrip (or as they call it, how to Make a Pirate Radio Station with an
iTrip.)

<http://www.engadget.com/entry/3597373383872462/>

>> Of course, the other problem is, once again, battery power. While
>> it's true that receiving a stream will also require battery power,
>> it'll require less to receive, passively, than to transmit, an
>> active, erm, activity.
>
> I'm no wireless tech; but from what I do understand, even streaming is a
> two-way conversation, because all TCP/IP-based services are. Every so
> often, the recipient has to send an acknowledgement packet so that the
> sender knows it's been receiving correctly. So while the transmitter
> wouldn't be pushing a lot of data while it's receiving a stream, it
> certainly wouldn't be 'passive' as far as I know, and the transmitter
> itself would probably stay 'hot' the whole time to send those
> acknowledgement packets.
>
> (The preceding was cribbed from my memory of a NetBITS article on
> Bandwidth vs. Latency. Anyone who knows more, please feel free to
> correct me. :) )

Theoretically a UDP based broadcast, instead of a TCP based broadcast,
would involve less battery power. UDP streams don't require a confirmation
reply for each packet received like TCP packets would. But there would
still be some upstream talk such as connecting to the hotspot, channel
hopping, selecting the stream, etc.... I can't imagine there would be more
than a 10-20% increase in battery time (vs. the sending mode), either
method though is going to drain the battery faster than the current models.
But isn't that why Belkin makes the battery pack?

[Nigel Stanger]
> Battery technology has failed
> to keep pace with the increasing power demands of mobile
> handsets (cameras, video, MP3 players, radios, etc., etc.,
> etc.).

Recently, it has become common to see more and more announcements about new
battery technology, though (since Nigel & I are both in NZ, the example I'll
give is:

<http://masseynews.massey.ac.nz/2003/masseynews/dec/dec01/stories/09-21-03.html>),

so I wonder if perhaps it's just that the need wasn't recognised early
enough, and so it's just taken a while for the battery people to catch up.
I think things will even up more over the next year or two.

What I would like to see is an iPod that can generate its own power - say
from photovoltaic (PV) cells exposed on the device. It's unlikely that it
could generate enough power to be self-sufficient, unless it was unused for
long periods when it was exposed to sunlight, but it would contribute.

Covering an iPod with PV cells could make it ugly, of course, but avoiding
that that's what a design team is for, and Apple seem to have pretty good
people in that department.

(I doubt this is feasible, but there are also those movement-powered
watches, the technology of which could contribute to charging an iPod.
There are probably other methods, too.)

Apart from simply more convenient, it would also be a nice thing to do from
an environment point of view...

=Tony Meyer

--On Wednesday, October 6, 2004 6:55 AM -0700 Tony Meyer
<ta-meyerihug.co.nz> wrote:

> What I would like to see is an iPod that can generate its own power - say
> from photovoltaic (PV) cells exposed on the device. It's unlikely that it
> could generate enough power to be self-sufficient, unless it was unused
> for long periods when it was exposed to sunlight, but it would contribute.
>
> Covering an iPod with PV cells could make it ugly, of course, but avoiding
> that that's what a design team is for, and Apple seem to have pretty good
> people in that department.

Maybe put the solar cells on your clothing instead?

<http://www.voltaicsystems.com/index.shtml>
<http://www.scottevest.com/v3_store/access_solar.shtml>

And somebody does make solar powered cellphone batteries.

<http://www.snpower.com/products.htm>

Not sure how good any of those are, I found the links via Gizmodo.
<http://www.gizmodo.com/>

Kevin

On 6/10/04 2:55 pm, "Tony Meyer" <ta-meyerihug.co.nz> wrote:

> Apart from simply more convenient, it would also be a nice thing to do from
> an environment point of view...

Would it?

I haven't kept up to date, but about 20 - 30 years ago (when energy costs
were much cheaper) it was reckoned that the energy required to make a PV
cell would take that cell 250 years to generate!

I would expect that (as with all things electronic) the production costs
will have come down, but could you reasonably expect a PV cell to recover
it's own energy cost when used to power a 'short life' item like a piece of
consumer electronics?

--
Barry

At 1:51 PM -0700 2004/10/07, Barry Wainwright wrote:
>I haven't kept up to date, but about 20 - 30 years ago (when energy costs
>were much cheaper) it was reckoned that the energy required to make a PV
>cell would take that cell 250 years to generate!
>
>I would expect that (as with all things electronic) the production costs
>will have come down, but could you reasonably expect a PV cell to recover
>it's own energy cost when used to power a 'short life' item like a piece of
>consumer electronics?

        Take a look to back issues of <http://homepower.com/>. The energy
payback for roof-mounted solar cells is certainly under 20 years (I think I
recall on order of 5 or 6 years). In a perfect economic world, the price of
an item would reflect the full cost to produce that item, which of course
would include all the energy costs. Unfortunately, many of the costs for
items are not included because some of those costs (military support of oil
industry, significant tax incentives for various industries, disposal
costs, pollution effects, etc.) are hard to figure out or just forgotten
about. The fact that solar electric power production is even in the
ballpark in terms of cost per watt generated with more established forms of
generation should indicate how "economical" it actually is, in absolute
terms.

On 8/10/04 2:25 am, "Johann Beda" <st-tidbitsbeda.ca> wrote:

> At 1:51 PM -0700 2004/10/07, Barry Wainwright wrote:
>> I haven't kept up to date, but about 20 - 30 years ago (when energy costs
>> were much cheaper) it was reckoned that the energy required to make a PV
>> cell would take that cell 250 years to generate!
>>
>
> Take a look to back issues of <http://homepower.com/>. The energy
> payback for roof-mounted solar cells is certainly under 20 years (I think I
> recall on order of 5 or 6 years).

Even taking your figure of 5-6 years, that applies to roof mounted solar
panels which are generating 8 - 16 hours per day! For an iPod type of
product, it would be unreasonable to expect them to generate for more than 3
- 4 hours per day on average, meaning you need to keep your iPod for 20
years to pay back the energy!

--
Barry

[This thread has veered way off the original topic, so let's bring it to a close... -Adam]

At 5:23 PM +0100 2004/10/08, Barry Wainwright wrote:
>On 8/10/04 2:25 am, "Johann Beda" wrote:
>> At 1:51 PM -0700 2004/10/07, Barry Wainwright wrote:
>>> I haven't kept up to date, but about 20 - 30 years ago (when energy costs
>>> were much cheaper) it was reckoned that the energy required to make a PV
>>> cell would take that cell 250 years to generate!
>>
>> Take a look to back issues of <http://homepower.com/>. The energy
>> payback for roof-mounted solar cells is certainly under 20 years (I think I
>> recall on order of 5 or 6 years).
>
>Even taking your figure of 5-6 years, that applies to roof mounted solar
>panels which are generating 8 - 16 hours per day! For an iPod type of
>product, it would be unreasonable to expect them to generate for more than 3
>- 4 hours per day on average, meaning you need to keep your iPod for 20
>years to pay back the energy!

        Sure, but once you start talking about portable types of products,
the "energy payback" type of calculation becomes a bit less relevant - the
point of such a product is to supply power where it would otherwise be
impossible or difficult to obtain by other means. If that power comes by
way of "embedded energy" then so be it.

        In this type of situation you have to define what you are comparing
things with. If you need something that can provide you with a few hours of
run-time every few days, for a few months, while living in the middle of
the Sahara desert, a solar panel is probably a better investment than a
half dozen car batteries. Comparing to the price to plug it in is sort of
pointless.