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| Author |
Message |
Ken Smith
Guest
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 Posted: Mon Jun 13, 2005 2:03 pm Post subject: Re: 9V batteries |
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In article <42ad3d04$0$1797$afc38c87@news.optusnet.com.au>,
Mr.T <MrT@home> wrote:
| Quote: |
"Rich Grise" <richgrise@example.net> wrote in message
news:pan.2005.06.11.23.41.21.110591@example.net...
Since AA packs a lot more Watthours per cubic inch than a 9V
Does it? I'm interested in your calculations.
There should be a market then for someone to simply put the exact same
technology into a 9V pack.
|
Pry apart a 9V and you will see why the AA packs more energy per unit
volume. There is a lot of the internal space used up by the need to
interconnect the cells and isolate them from each other.
I suspect that the cells in the 9V are actually a little better than the
AA in energy per volume but I don't think it is by enough to make up for
the about 1/3rd of the space that is not actually a cell.
--
--
kensmith@rahul.net forging knowledge |
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Spehro Pefhany
Guest
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| Posted: Mon Jun 13, 2005 3:05 pm Post subject: Re: 9V batteries |
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On Mon, 13 Jun 2005 14:03:35 +0000 (UTC), the renowned
kensmith@green.rahul.net (Ken Smith) wrote:
| Quote: | In article <42ad3d04$0$1797$afc38c87@news.optusnet.com.au>,
Mr.T <MrT@home> wrote:
"Rich Grise" <richgrise@example.net> wrote in message
news:pan.2005.06.11.23.41.21.110591@example.net...
Since AA packs a lot more Watthours per cubic inch than a 9V
Does it? I'm interested in your calculations.
There should be a market then for someone to simply put the exact same
technology into a 9V pack.
Pry apart a 9V and you will see why the AA packs more energy per unit
volume. There is a lot of the internal space used up by the need to
interconnect the cells and isolate them from each other.
I suspect that the cells in the 9V are actually a little better than the
AA in energy per volume but I don't think it is by enough to make up for
the about 1/3rd of the space that is not actually a cell.
|
Comparing the consumer cells/batteries at a given point in time from
one manufacturer (GP), you have the capacity of their highest capacity
AA cells is typically 2450mAh (marked "2500"), while(st) their highest
capacity 9V battery is 210mAh (marked 200). Since the 9V battery is 7
cells in series, the 9V battery has only 60% of the energy storage
capacity of the AA cell.
On a weight basis, the 9V battery is 42.5g and the AA cells is 31g, so
the AA cell comes out even further ahead (2.28:1).
On a volume basis, the AA cell fits in a cylinder 14.5mm diameter by
50.5mm long (including the end button), so 8339mm^3. The 9V battery
fits in a box 48.5mm x 26.5mm x 15.7mm (including the snaps) or
20,180mm^3.
On a volume basis, the AA cell comes out ahead by 4:1. If you more
realistically use a box (rectangular prism) that just encloses the AA
cylinder for the occupied volume, it's still ahead by more than 3:1.
Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com |
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Mr.T
Guest
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| Posted: Tue Jun 14, 2005 6:02 am Post subject: Re: 9V batteries |
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|
"Ken Smith" <kensmith@green.rahul.net> wrote in message
news:d8k3nn$cra$1@blue.rahul.net...
| Quote: | Does it? I'm interested in your calculations.
There should be a market then for someone to simply put the exact same
technology into a 9V pack.
Pry apart a 9V and you will see why the AA packs more energy per unit
volume. There is a lot of the internal space used up by the need to
interconnect the cells and isolate them from each other.
|
So the casing of a AAA cell (and cell holder) doesn't do exactly the same?
Not to mention all that wasted area between cylindrical cells.
| Quote: | I suspect that the cells in the 9V are actually a little better than the
AA in energy per volume but I don't think it is by enough to make up for
the about 1/3rd of the space that is not actually a cell.
|
I note you have included NO data to back up your assertion.
Your claim of more energy per unit volume is looking dubious then.
MrT. |
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Mr.T
Guest
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| Posted: Tue Jun 14, 2005 6:02 am Post subject: Re: 9V batteries |
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"Spehro Pefhany" <speffSNIP@interlogDOTyou.knowwhat> wrote in message
news:2u6ra1tqrciomic8bkb7llehbjb7h5umsj@4ax.com...
| Quote: | Comparing the consumer cells/batteries at a given point in time from
one manufacturer (GP), you have the capacity of their highest capacity
AA cells is typically 2450mAh (marked "2500"), while(st) their highest
capacity 9V battery is 210mAh (marked 200). Since the 9V battery is 7
cells in series, the 9V battery has only 60% of the energy storage
capacity of the AA cell.
|
Interesting to see some actual data for a change, however it would be more
appropriate to compare batteries of the same range, and similar size. I am
not familiar with the GP cells you refer to, but I suspect the top of the
range AA cell is a newer technology. If you now use D cells instead, the
figures are MUCH greater in favour of D cells than AA.
Obviously by your reasoning nobody should ever use AA cells since D cells
are far better!
In fact using only one D cell with a DC-DC inverter *IS* the best way to
power most equipment!
I'll let you do the calculations, then compare the cost of one D cell versus
six AA cells!!!!!!!!!
Personally I would NEVER consider six AA cells as a good replacement for a
9V battery when a **FAR** better option exists.
| Quote: | On a weight basis, the 9V battery is 42.5g and the AA cells is 31g, so
the AA cell comes out even further ahead (2.28:1).
|
And a D cell much further still.
Now where are the figures for six AAA cells and battery holder?
| Quote: | On a volume basis, the AA cell fits in a cylinder 14.5mm diameter by
50.5mm long (including the end button), so 8339mm^3. The 9V battery
fits in a box 48.5mm x 26.5mm x 15.7mm (including the snaps) or
20,180mm^3.
|
Shame you cannot use that wasted space between cells.
| Quote: | On a volume basis, the AA cell comes out ahead by 4:1. If you more
realistically use a box (rectangular prism) that just encloses the AA
cylinder for the occupied volume, it's still ahead by more than 3:1.
|
As is the size difference unfortunately.
MrT. |
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Spehro Pefhany
Guest
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| Posted: Tue Jun 14, 2005 12:02 pm Post subject: Re: 9V batteries |
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On Tue, 14 Jun 2005 15:28:57 +1000, the renowned "Mr.T" <MrT@home>
wrote:
| Quote: |
"Spehro Pefhany" <speffSNIP@interlogDOTyou.knowwhat> wrote in message
news:2u6ra1tqrciomic8bkb7llehbjb7h5umsj@4ax.com...
Comparing the consumer cells/batteries at a given point in time from
one manufacturer (GP), you have the capacity of their highest capacity
AA cells is typically 2450mAh (marked "2500"), while(st) their highest
capacity 9V battery is 210mAh (marked 200). Since the 9V battery is 7
cells in series, the 9V battery has only 60% of the energy storage
capacity of the AA cell.
Interesting to see some actual data for a change, however it would be more
appropriate to compare batteries of the same range, and similar size. I am
not familiar with the GP cells you refer to, but I suspect the top of the
range AA cell is a newer technology.
|
Really, who cares?
This manufacturer has a wide line with three types of 9V cell alone.
You think they're going to improve the 9V cell just for you? The AA
cells have not made a sudden leap in capacity. Every six months or
year they introduce an new model that is slightly better in capacity.
They sell the lower capacity cells in lower cost markets such as
mainland China (in fact, they're the only ones available). If D cells
and 9V batteries are unpopular with product designers and therefore
don't have the same competitive pressure to make high-performance
designs, that's taken into account by looking at the "best available"
units.
| Quote: | If you now use D cells instead, the
figures are MUCH greater in favour of D cells than AA.
Obviously by your reasoning nobody should ever use AA cells since D cells
are far better!
|
Only in energy storage per battery.
*If* you read and understood my entire post, you would have seen the
other two comparisons-- of energy storage per gram and energy storage
per unit volume. In *all* cases, the best available AA cell of that
brand/series beats the best available 9V cell of that brand/series by
a considerable margin.
| Quote: | In fact using only one D cell with a DC-DC inverter *IS* the best way to
power most equipment!
I'll let you do the calculations, then compare the cost of one D cell versus
six AA cells!!!!!!!!!
|
Why don't *you* do some calculations? It should be trivially easy to
find the data and the mensuration formulas if you don't remember them.
| Quote: | Personally I would NEVER consider six AA cells as a good replacement for a
9V battery when a **FAR** better option exists.
|
Who said anything about six? It takes seven to equal the voltage of a
typical 9V battery (some are higher), and my comparison was for a
single cell vs. a 9V battery. Hopefully it's easy enough to multiply
by the number of batteries in the case of total capacity. It won't
affect the energy storage per gram or per cubic millimeter numbers,
obviously!
| Quote: | On a weight basis, the 9V battery is 42.5g and the AA cells is 31g, so
the AA cell comes out even further ahead (2.28:1).
And a D cell much further still.
|
Got any numbers to back up that (quite dubious) assertion?
| Quote: | Now where are the figures for six AAA cells and battery holder?
|
Waiting for you to calculate them. I have no need of the numbers at
present.
| Quote: | On a volume basis, the AA cell fits in a cylinder 14.5mm diameter by
50.5mm long (including the end button), so 8339mm^3. The 9V battery
fits in a box 48.5mm x 26.5mm x 15.7mm (including the snaps) or
20,180mm^3.
Shame you cannot use that wasted space between cells.
|
In some cases some of it can be used by a clever designer. It can't be
if the space is filled by a steel shell.
| Quote: | On a volume basis, the AA cell comes out ahead by 4:1. If you more
realistically use a box (rectangular prism) that just encloses the AA
cylinder for the occupied volume, it's still ahead by more than 3:1.
As is the size difference unfortunately.
MrT.
|
The AA cell is >3 times better than a 9V battery in *energy per cubic
millimeter*. "Size difference" is already taken into account in this
number. You want to take it into account again?
Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com |
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Arny Krueger
Guest
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| Posted: Tue Jun 14, 2005 12:02 pm Post subject: Re: 9V batteries |
|
|
Spehro Pefhany wrote:
| Quote: | On a volume basis, the AA cell fits in a cylinder 14.5mm
diameter by
50.5mm long (including the end button), so 8339mm^3. The
9V battery
fits in a box 48.5mm x 26.5mm x 15.7mm (including the
snaps) or
20,180mm^3.
|
Readily available DC-DC converters seem to want at least 2.7
volts input voltage, to produce 5 volts. So, you're stuck
with using 2 AA cells, which are somewhat longer and wider
than one 9 volt cell.
OTOH, Maxim shows a wide range of converters with inputs as
low as 0.6 volts and plenty rated at 1.5 volt input. A wide
range of output voltages is listed as well.
http://para.maxim-ic.com/compare.asp?Fam=DCDC_All&Tree=PowerSupplies&HP=PowerSupplies.cfm&ln=&SORD=1751&FT_1751=21300&ITEMLIST=15C03,15C04,15C05,15C06,15C09,15C0A,15C1A,15C1B,15C26,15C27,15C28,15C2A,15C33,15C34,15C37,15C38,15C39,15C3A,15C3B,15C3C,15C53,15C56,15C57,15C5C,15C5E,15C5F,15C60,15C68,15C69,15C6A,15C6B,15C82,15C83,15C84,15C89,15C8A,15C8B,15C93,15C94,15C99,15CA9,15CAA,15CAB,15CAC,15CB2,15CBA,15CBB,15CBF,15CC0,15CC3,15CC4,15CCC,15CCD,15CCE,15CCF,15CE9,15CEA,15CEF,15CF0,15CF1,15CF2,15CF8,15CF9,15D07,15D08,15D0D,15D0E,15D0F,15D10,15D11,15D12,15D13,15D1A,15D1B,15D1C,15D1D,15D1E,15D34,15D46,15D47,15D48,15D5F,15D67,15D68,15D69,15D86,15D87,15D92,15D97,15DAE,15DAF,15DB0,15DB1,15DB2,15DB3,15DB4,15DB9,15DBA,15DBB,15DBC,15DBD,15DC0
| Quote: | On a volume basis, the AA cell comes out ahead by 4:1. If
you more
realistically use a box (rectangular prism) that just
encloses the AA
cylinder for the occupied volume, it's still ahead by more
than 3:1. |
It looks like the DC-DC converter could be packaged so it
had about 1/6 the volume of a 9 volt battery.
All things considered the 2-AA cell solution is still ahead
by something like 2:1 in terms of power per volume, but at a
significant cost in terms of minimum size and cost.
It's probably the cost that dominates most design decisions
for consumer products. A DC-DC converter could add $20-30 to
the final cost.
It seems like a single-AA cell solution could be practical
for higher end wireless mics and earphones for pro audio,
for example. |
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Spehro Pefhany
Guest
|
| Posted: Tue Jun 14, 2005 1:03 pm Post subject: Re: 9V batteries |
|
|
On Tue, 14 Jun 2005 07:54:25 -0400, the renowned "Arny Krueger"
<arnyk@hotpop.com> wrote:
| Quote: | Spehro Pefhany wrote:
On a volume basis, the AA cell fits in a cylinder 14.5mm
diameter by
50.5mm long (including the end button), so 8339mm^3. The
9V battery
fits in a box 48.5mm x 26.5mm x 15.7mm (including the
snaps) or
20,180mm^3.
Readily available DC-DC converters seem to want at least 2.7
volts input voltage, to produce 5 volts. So, you're stuck
with using 2 AA cells, which are somewhat longer and wider
than one 9 volt cell.
|
Many of the current crop of flash MP3 players seem to use a single
alkaline or NiMH AAA cell.
| Quote: | OTOH, Maxim shows a wide range of converters with inputs as
low as 0.6 volts and plenty rated at 1.5 volt input. A wide
range of output voltages is listed as well.
http://para.maxim-ic.com/compare.asp?Fam=DCDC_All&Tree=PowerSupplies&HP=PowerSupplies.cfm&ln=&SORD=1751&FT_1751=21300&ITEMLIST=15C03,15C04,15C05,15C06,15C09,15C0A,15C1A,15C1B,15C26,15C27,15C28,15C2A,15C33,15C34,15C37,15C38,15C39,15C3A,15C3B,15C3C,15C53,15C56,15C57,15C5C,15C5E,15C5F,15C60,15C68,15C69,15C6A,15C6B,15C82,15C83,15C84,15C89,15C8A,15C8B,15C93,15C94,15C99,15CA9,15CAA,15CAB,15CAC,15CB2,15CBA,15CBB,15CBF,15CC0,15CC3,15CC4,15CCC,15CCD,15CCE,15CCF,15CE9,15CEA,15CEF,15CF0,15CF1,15CF2,15CF8,15CF9,15D07,15D08,15D0D,15D0E,15D0F,15D10,15D11,15D12,15D13,15D1A,15D1B,15D1C,15D1D,15D1E,15D34,15D46,15D47,15D48,15D5F,15D67,15D68,15D69,15D86,15D87,15D92,15D97,15DAE,15DAF,15DB0,15DB1,15DB2,15DB3,15DB4,15DB9,15DBA,15DBB,15DBC,15DBD,15DC0
On a volume basis, the AA cell comes out ahead by 4:1. If
you more
realistically use a box (rectangular prism) that just
encloses the AA
cylinder for the occupied volume, it's still ahead by more
than 3:1.
It looks like the DC-DC converter could be packaged so it
had about 1/6 the volume of a 9 volt battery.
|
Chances are you're going to use a switching regulator anyway if you
want good battery life. Otherwise you're probably throwing away more
than half the energy.
| Quote: | All things considered the 2-AA cell solution is still ahead
by something like 2:1 in terms of power per volume, but at a
significant cost in terms of minimum size and cost.
It's probably the cost that dominates most design decisions
for consumer products. A DC-DC converter could add $20-30 to
the final cost.
|
It's a complex comparison-- case size, styling, and battery life and
often charger considerations have to be taken into account in a
portable product. I don't know how much the newest small stepup
converters cost in consumer production volume, but mature SMPS chips
are in the 10 to 20-cent range. The newest ones could be 5 or 10 times
that, even in volume.
The size of things like digital cameras, games etc. have decreased to
the point where they often insist on newer types of batteries. These
things are expensive to replace, and you can't take advantage of
improvements in technology. My first digital camera took 4 AA cells,
and I now use 2450mAh batteries in it. The first ones were 1300mAh.
That's a considerable improvement (over 6 years). My more recent
purchases use special Li-ion batteries. At least one company is
pushing security chips to prevent the use of third-party battery packs
in new designs. Li-ion cells also need a more sophisticated charger
technology AFAIUI.
But compare a typical Li-ion cell-
3.7V output. 5.5mm x 34mm x 50.4mm and only 21 grams. 860mAh at 3.7V.
That's almost half the thickness of a AAA cell and has about the
energy storage capacity and voltage output of 3 typical AAA cells.
Very tempting.
| Quote: | It seems like a single-AA cell solution could be practical
for higher end wireless mics and earphones for pro audio,
for example.
|
Yes, I would think it would be good. Or even a AAA*.
But the little flat Li-ion batteries would be even sleeker.
* pronounced "triple-A", hence the "a".
Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com |
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Arny Krueger
Guest
|
| Posted: Tue Jun 14, 2005 1:03 pm Post subject: Re: 9V batteries |
|
|
Spehro Pefhany wrote:
| Quote: | On Tue, 14 Jun 2005 07:54:25 -0400, the renowned "Arny
Krueger"
arnyk@hotpop.com> wrote:
Spehro Pefhany wrote:
On a volume basis, the AA cell fits in a cylinder 14.5mm
diameter by
50.5mm long (including the end button), so 8339mm^3. The
9V battery
fits in a box 48.5mm x 26.5mm x 15.7mm (including the
snaps) or
20,180mm^3.
Readily available DC-DC converters seem to want at least
2.7
volts input voltage, to produce 5 volts. So, you're stuck
with using 2 AA cells, which are somewhat longer and
wider
than one 9 volt cell.
Many of the current crop of flash MP3 players seem to use
a single
alkaline or NiMH AAA cell.
|
I don't know what they use for power internally. Based on
the limited headphone drive they provide, they may in fact
be running off the 1.5 volt directly.
| Quote: | OTOH, Maxim shows a wide range of converters with inputs
as
low as 0.6 volts and plenty rated at 1.5 volt input. A
wide
range of output voltages is listed as well.
http://para.maxim-ic.com/compare.asp?Fam=DCDC_All&Tree=PowerSupplies&HP=PowerSupplies.cfm&ln=&SORD=1751&FT_1751=21300&ITEMLIST=15C03,15C04,15C05,15C06,15C09,15C0A,15C1A,15C1B,15C26,15C27,15C28,15C2A,15C33,15C34,15C37,15C38,15C39,15C3A,15C3B,15C3C,15C53,15C56,15C57,15C5C,15C5E,15C5F,15C60,15C68,15C69,15C6A,15C6B,15C82,15C83,15C84,15C89,15C8A,15C8B,15C93,15C94,15C99,15CA9,15CAA,15CAB,15CAC,15CB2,15CBA,15CBB,15CBF,15CC0,15CC3,15CC4,15CCC,15CCD,15CCE,15CCF,15CE9,15CEA,15CEF,15CF0,15CF1,15CF2,15CF8,15CF9,15D07,15D08,15D0D,15D0E,15D0F,15D10,15D11,15D12,15D13,15D1A,15D1B,15D1C,15D1D,15D1E,15D34,15D46,15D47,15D48,15D5F,15D67,15D68,15D69,15D86,15D87,15D92,15D97,15DAE,15DAF,15DB0,15DB1,15DB2,15DB3,15DB4,15DB9,15DBA,15DBB,15DBC,15DBD,15DC0
On a volume basis, the AA cell comes out ahead by 4:1.
If
you more
realistically use a box (rectangular prism) that just
encloses the AA
cylinder for the occupied volume, it's still ahead by
more
than 3:1.
It looks like the DC-DC converter could be packaged so it
had about 1/6 the volume of a 9 volt battery.
Chances are you're going to use a switching regulator
anyway if you
want good battery life. Otherwise you're probably throwing
away more
than half the energy.
|
The deviced I've referenced are all based on switchmode
operation.
| Quote: | All things considered the 2-AA cell solution is still
ahead
by something like 2:1 in terms of power per volume, but
at a
significant cost in terms of minimum size and cost.
It's probably the cost that dominates most design
decisions
for consumer products. A DC-DC converter could add $20-30
to
the final cost.
It's a complex comparison-- case size, styling, and
battery life and
often charger considerations have to be taken into account
in a
portable product. I don't know how much the newest small
stepup
converters cost in consumer production volume, but mature
SMPS chips
are in the 10 to 20-cent range. The newest ones could be 5
or 10 times
that, even in volume.
|
The prices I see are in the 10x range.
| Quote: | The size of things like digital cameras, games etc. have
decreased to
the point where they often insist on newer types of
batteries. These
things are expensive to replace, and you can't take
advantage of
improvements in technology. My first digital camera took 4
AA cells,
and I now use 2450mAh batteries in it. The first ones were
1300mAh.
That's a considerable improvement (over 6 years). My more
recent
purchases use special Li-ion batteries. At least one
company is
pushing security chips to prevent the use of third-party
battery packs
in new designs. Li-ion cells also need a more
sophisticated charger
technology AFAIUI.
But compare a typical Li-ion cell-
3.7V output. 5.5mm x 34mm x 50.4mm and only 21 grams.
860mAh at 3.7V.
That's almost half the thickness of a AAA cell and has
about the
energy storage capacity and voltage output of 3 typical
AAA cells.
Very tempting.
|
Agreed, and no DC-DC converter would be required.
| Quote: | It seems like a single-AA cell solution could be
practical
for higher end wireless mics and earphones for pro audio,
for example.
Yes, I would think it would be good. Or even a AAA*.
But the little flat Li-ion batteries would be even
sleeker. |
Trouble with the Li-ion cells is that every device seems to
want a different one. |
|
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Spehro Pefhany
Guest
|
| Posted: Tue Jun 14, 2005 1:03 pm Post subject: Re: 9V batteries |
|
|
On Tue, 14 Jun 2005 08:44:01 -0400, the renowned "Arny Krueger"
<arnyk@hotpop.com> wrote:
| Quote: | I don't know what they use for power internally. Based on
the limited headphone drive they provide, they may in fact
be running off the 1.5 volt directly.
|
No, *definitely* not. The last one I bought (Creative) has a blue LED
display backlight. That requires 3.5V. ;-) Similarly with the
Nike/Philips.
| Quote: | Trouble with the Li-ion cells is that every device seems to
want a different one.
|
Which may not trouble the OEM so much. 8-(
Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com |
|
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Spehro Pefhany
Guest
|
| Posted: Tue Jun 14, 2005 2:08 pm Post subject: Re: 9V batteries |
|
|
On Tue, 14 Jun 2005 08:56:56 -0400, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:
| Quote: | On Tue, 14 Jun 2005 08:44:01 -0400, the renowned "Arny Krueger"
arnyk@hotpop.com> wrote:
I don't know what they use for power internally. Based on
the limited headphone drive they provide, they may in fact
be running off the 1.5 volt directly.
No, *definitely* not. The last one I bought (Creative) has a blue LED
display backlight. That requires 3.5V. ;-) Similarly with the
Nike/Philips.
|
P.S.
I just looked, the Nike/Philips unit uses a Sigmatel 3410L SOC which
has the DC-DC converter logic on chip (along with the 65MHz DSP, USB
interface and lots of other stuff). It uses a (relatively) large
external 4.7uH inductor and what appears to be quite a few other
discrete (cheap) components. The only ICs are the SOC and two Toshiba
TC58DVM92A1FT00 512Mb flash memory chips, the rest of the 150 or so
parts are discretes, not even an IC audio amplifier.
(photos about 200K each on 0.2" quadrille paper)
http://server2.hostingplex.com/~zstoretr/mp3top.jpg
(the inductor is the large black square to the lower right of the SOC)
http://server2.hostingplex.com/~zstoretr/mp3bot.jpg
http://www.toshiba.com/taec/components/Datasheet/TC58DVM92A1FT_030110.pdf
http://www.sigmatel.com/documents/App-Brief1-Flash-MP3-7-1.pdf
Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com |
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Ken Smith
Guest
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| Posted: Tue Jun 14, 2005 2:15 pm Post subject: Re: 9V batteries |
|
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In article <83ita11u0nspc331atu0ljndp8rjsaj167@4ax.com>,
Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> wrote:
[...]
| Quote: | Chances are you're going to use a switching regulator anyway if you
want good battery life. Otherwise you're probably throwing away more
than half the energy.
|
If you are doing modest quality audio, you may not put the regulator in
the circuit but instead use a class-D audio output.
--
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kensmith@rahul.net forging knowledge |
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Ken Smith
Guest
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| Posted: Tue Jun 14, 2005 2:18 pm Post subject: Re: 9V batteries |
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In article <42ae674a$0$16492$afc38c87@news.optusnet.com.au>,
Mr.T <MrT@home> wrote:
| Quote: |
"Ken Smith" <kensmith@green.rahul.net> wrote in message
news:d8k3nn$cra$1@blue.rahul.net...
[....]
I suspect that the cells in the 9V are actually a little better than the
AA in energy per volume but I don't think it is by enough to make up for
the about 1/3rd of the space that is not actually a cell.
I note you have included NO data to back up your assertion.
Your claim of more energy per unit volume is looking dubious then.
|
The numbers are in another part of this thread, kindly posted by
someone else and they support my suggestion.
--
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kensmith@rahul.net forging knowledge |
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Mr.T
Guest
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| Posted: Thu Jun 16, 2005 6:02 am Post subject: Re: 9V batteries |
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|
"Spehro Pefhany" <speffSNIP@interlogDOTyou.knowwhat> wrote in message
news:hheta1lfgh57ggjorg38i9ld9omv5d898k@4ax.com...
| Quote: | This manufacturer has a wide line with three types of 9V cell alone.
You think they're going to improve the 9V cell just for you?
|
It's not ME bitching about them. I only use them when appropriate.
| Quote: | If you now use D cells instead, the
figures are MUCH greater in favour of D cells than AA.
Obviously by your reasoning nobody should ever use AA cells since D cells
are far better!
Only in energy storage per battery.
|
No.
| Quote: | *If* you read and understood my entire post, you would have seen the
other two comparisons-- of energy storage per gram and energy storage
per unit volume. In *all* cases, the best available AA cell of that
brand/series beats the best available 9V cell of that brand/series by
a considerable margin.
|
Yes I read it, and still say a D cell has more energy per unit volume.
Possibly per unit weight, but I'll let you do the calculation for that if
you like :-)
| Quote: | Personally I would NEVER consider six AA cells as a good replacement for
a
9V battery when a **FAR** better option exists.
Who said anything about six? It takes seven to equal the voltage of a
typical 9V battery
|
Six alkaline cells = 9V, so I assume you are now talking NiMH. Of course
that only makes the situation worse size wise anyway.
However comparing apples with oranges does confuse the argument somewhat.
| Quote: | And a D cell much further still.
Got any numbers to back up that (quite dubious) assertion?
|
Yes, they are on the major battery manufacturers web sites.
| Quote: | Now where are the figures for six AAA cells and battery holder?
Waiting for you to calculate them. I have no need of the numbers at
present.
|
Nor I.
| Quote: | Shame you cannot use that wasted space between cells.
In some cases some of it can be used by a clever designer.
|
I can't say I've seen any of those clever designs then.
| Quote: | The AA cell is >3 times better than a 9V battery in *energy per cubic
millimeter*. "Size difference" is already taken into account in this
number. You want to take it into account again?
|
If you weren't stuck in the same groove, you might realise putting something
THREE times the size into a device which is supposed to be SMALL, is not
necessarily an option.
In this instance I am talking about SIZE period, not volumetric efficiency.
Run it off a Car battery if size is NOT an issue!
MrT. |
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Mr.T
Guest
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| Posted: Thu Jun 16, 2005 7:01 am Post subject: Re: 9V batteries |
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"Ken Smith" <kensmith@green.rahul.net> wrote in message
news:d8mp0d$bev$4@blue.rahul.net...
| Quote: | In article <42ae674a$0$16492$afc38c87@news.optusnet.com.au>,
Mr.T <MrT@home> wrote:
"Ken Smith" <kensmith@green.rahul.net> wrote in message
news:d8k3nn$cra$1@blue.rahul.net...
[....]
I suspect that the cells in the 9V are actually a little better than
the
AA in energy per volume but I don't think it is by enough to make up
for
the about 1/3rd of the space that is not actually a cell.
I note you have included NO data to back up your assertion.
Your claim of more energy per unit volume is looking dubious then.
The numbers are in another part of this thread, kindly posted by
someone else and they support my suggestion.
|
The figures are rather misleading, but you are probably correct this time.
Your "I suspect that the cells in the 9V are actually a little better than
the AA in energy per volume" is still doubtful though.
I still think a DC-DC inverter is the best solution, as you can have small
and/or higher capacity as well as lower battery costs.
However this thread is getting too far into comparing apples with oranges,
IMO.
MrT. |
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Jonathan Westhues
Guest
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| Posted: Thu Jun 16, 2005 8:03 am Post subject: Re: 9V batteries |
|
|
"Mr.T" <MrT@home> wrote in message
news:42b114b3$0$16493$afc38c87@news.optusnet.com.au...
| Quote: | *If* you read and understood my entire post, you would have seen the
other two comparisons-- of energy storage per gram and energy storage
per unit volume. In *all* cases, the best available AA cell of that
brand/series beats the best available 9V cell of that brand/series by
a considerable margin.
Yes I read it, and still say a D cell has more energy per unit volume.
Possibly per unit weight, but I'll let you do the calculation for that if
you like :-)
|
I used the alkaline Energizer Industrial series, because Digikey sells
them. All capacities are to 0.8 V per cell, at 25 mA. That puts 9V
batteries at a slight disadvantage, because that is more watts with a 9V
than a 1.5V, but it looks like the error is small enough that I wouldn't
do better trying to read a capacity off the graph.
The prices are in ones. They provide a volume, which appears to be more
or less the volume of the cylinder, but I also calculated the `bounding
box' volume.
AA cell:
m=23 g, Q=2779 mA*h, E=4168 mW*h, $=0.75 CAD, V=8.1 or 9.8 cm^3
E/m = 181, E/V = 515 or 425, E/$ = 5557
D cell:
m=142 g, Q=20500 mA*h, E=30750 mW*h, $=1.69 CAD, V=55.9 or 69.4 cm^3
E/m = 216, E/V = 550 or 443, E/$ = 18195
9V battery:
m=45.6 g, Q=625 mA*h, E=5625 mW*h, $=2.86 CAD, V=21.1 cm^3
E/m = 123, E/V = 267, E/$ = 1966
6V lantern battery:
m=665 g, Q=18000 mA*H, E=108000 mW*h, $=13.02 CAD, V=440.4 cm^3
E/m = 162, E/V = 245, E/$ = 8295
The energy figures are wrong because the voltage declines during the
life of the cell, but they will be equally wrong for all types so I
think that the numbers can be compared.
So that means that a AA cell is twice as good as (E/V) or 50% better
than (E/m) a 9V battery. A D cell is about as good as (E/V) or 20%
better than (E/m) a AA cell. That is sort of like what I expected.
What's wrong with the lantern battery though? Is there a good reason why
it's worse or did I make a silly mistake somewhere? Different capacity vs.
internal resistance tradeoff?
Jonathan |
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