Tablet battery question

SC Tom wrote:


"Stan Brown" wrote in message
t...
On Fri, 14 Mar 2014 08:20:02 -0400, SC Tom wrote:

"Stan Brown" wrote in message
t...

I think I want to get an external battery pack for my Kindle Fire HDX
7", but I don't think this is it.


I bought this bad boy for use with my 10" tablet:

http://www.amazon.com/gp/product/B00FDK2G2C/ref=oh_details_o09_s00_i00?ie=UTF8&psc=1


Oh my - that looks like it can do the job.

I read all the Q&As -- kind of frustrating, because often the answers
to the same question contradicted each other. For example, some said
you can charge it while using it and others said that shortens the
life of the unit.

From the pictures, it looks like you charge it through the same port
that you ten use to suck charge into the tablet or other device; is
that right?

And the pictures didn't show any way to plug it into the wall. I did
see a USB cable -- do we just plug it into a USB wall connector, like
this one

http://www.amazon.com/gp/product/B006GWO5WK

(That came with my KF in early December -- I was amazed to read that
they're now sold separately and no longer included.)

One more question, as long as I'm asking: There's no danger of frying
a device with these external chargers, is there? I mean, it's just a
matter of a device charging faster or slower based on the power
output of the external charger, is that right?

It's charged through the µUSB port on the side (you can see it on the
5th picture down); the two USB ports on the end are for 1A and 2.1A
output. It comes with two USB cables- one ~28" long and the other ~6".
Each cable has a barrel connector that allows the use of the adapters
that come with it. I use my Asus 2.0A charger to recharge the battery
pack- no charger is included with it. The Amazon one is 1.8A, so it
would probably take a little longer than my 2.0A charger. Even so, if
it's down to about 25% or less, it takes overnight to recharge it fully.

I've never tried charging it while using it to charge my Asus. I have
enough chargers lying around that I can do each separately :-) I would
think that if it was an "intelligent" battery pack, and the device being
charged by the battery pack drew less current than the battery pack
being charged, then the charging of the battery pack would take less
precedence over the device being charged, and both would be charged. But
if the device drew more than the battery pack, the battery pack would
basically be bypassed while the device was being charged. Does that make
sense, in a roundabout, convoluted way?

The speed of the tablet/phone being recharged depends more on its
capabilities than on the device charging it. If the tablet will only
draw .7A max while charging, it won't make any difference if you use the
1A or the 2.1A port. If the tablet draws 1.7A while charging, it will
charge faster on the 2.1A port than it will on the 1A one. You can use a
PCs USB port to charge a tablet or a phone, but with its max 500mA (.5A)
output, it'll take a lot longer to finish than using the battery pack or
a wall charger.

I have never heard of a device being fried from using a battery pack,
although I guess it's possible, just like it's possible for a wall
charger to malfunction and fry your tablet, or a PC PSU to short out and
fry the MB. When Murphy's Law is in effect, anything is possible :-)

You could take it apart and see how it's constructed.

Just some guesses on the nature of the problem. Using your observations
on input and output options. The fact it's 5V on input and output,
probably means the battery (being a multiple of 3.x V), is some
other voltage. Maybe 12 to 14 volts or so for the central battery.
I've seen high voltage versions of regulators, that can run at up to
50V on input, so the battery could be made of a very large number of
cells, if desired. And that would give you more watt-hours to work with.

+-- cc/cv charge ---+---------+ --- cutoff on low voltage
| | |
5V in ---- boost 5V ----- buck ----- 5V regulated output
uUSB battery --- converter
|
GND -----------------------------+-------------------

While you could do a battery of less than 5V (single cell, huge) and
put boost converters on either side, that's not a commonly available
format of battery. And probably dangerous as well. Using a string of
smaller batteries, to a much higher voltage, makes the battery a storer
of "watt-hours". Then, it's a matter of voltage conversion on the
input and output side, to achieve a desired result. The buck converter
might be 80-85% efficient, so the battery pack would get "warm" when
charging things.

On a laptop, the wall adapter output voltage is such, it can be
used directly for the charging step. So there's no need for a
boost stage on the input. It might still require a buck regulator
on the output, to drop 14.4V to the much lower voltages the laptop
might need.

The battery discharge curve, may not be flat enough to meet a +/-5%
voltage regulation spec. Which is why a buck converter can
hold things very stable (at the expense of efficiency).

As long as the pack has voltage isolation as in the drawing above,
I don't see frying as being a possibility. You can look at the
charging process here, and even if the battery terminal voltage goes
up a bit during one of the charging stages (the CV stage), the buck
converter would be well able to handle the higher voltage, and
hide voltage variation at the output so they're a lot lower than 5%.

Charging process
http://batteryuniversity.com/learn/a..._ion_batteries

Discharge curve
http://batteryuniversity.com/learn/a...ased_batteries

It would be pretty hard to make a "raw battery pack", and meet safety
and functionality requirements. Removing protections around the lithium
would just be asking for trouble.

There are battery types less dangerous than lithium systems,
but they're also not as dense a form of storage. Lead-acid might
take more abuse than lithium, in a contest.

Paul

On Sat, 15 Mar 2014 15:37:04 -0400, Stan Brown wrote:

On Sat, 15 Mar 2014 08:52:41 -0400, SC Tom wrote:
The speed of the tablet/phone being recharged depends more on its
capabilities than on the device charging it. If the tablet will only draw
.7A max while charging, it won't make any difference if you use the 1A or
the 2.1A port. If the tablet draws 1.7A while charging, it will charge
faster on the 2.1A port than it will on the 1A one. You can use a PCs USB
port to charge a tablet or a phone, but with its max 500mA (.5A) output,
it'll take a lot longer to finish than using the battery pack or a wall
charger.

Thanks for this. (Thanks also for your other descriptions. I snipped
them because they told me what I needed to know, and I don't have
questions.)

Let me see if I understand this last bit. The output of an external
charger cannot somehow over-drive the device it is charging. The
amount of current that flows is equal to the lesser of the charger's
output and what the device will accept.

If that's the case, then if I'm charging only one device, I may as
well always plug it into the 2.1A output, correct?

(FWIW, according to this review
http://www.amazon.com/Kindle-Fire-HD...Wi-Fi/product-
reviews/B00CUU1CGY
the KF HDX 7's battery is only 4500 mAh. When plugged into the wall
with Amazon's fast 9 W charger, it takes about four hours to charge
from 1% to 100%, which means about 1100 mA. Hmm, 9 W / 1.1 A = 8 V.
Does that seem reasonable?

Correction. The charger that came with my KF is 5 W, not 9 W. (I
happened to run across the original box this afternoon, and it lists
the charger among the contents.) So 5 W / 1.1 A = 4.4 V.

If I understand correctly, then the charger Tom suggests will
recharge my KF faster than Amazon's supplied wall plug.

So if I plug my device into the 2.1A slot, what happens? Does it
charge almost twice as fast, or does it still accept only 1.1 A? If
I'm understanding you, it would still accept only 1.1 A. (I'm
assuming that Amazon's charger, packed with the KF, delivers as much
current as the device will accept; it would be kind of silly
otherwise.)



--
Stan Brown, Oak Road Systems, Tompkins County, New York, USA
http://OakRoadSystems.com
Shikata ga nai...

On 3/15/2014, Stan Brown posted:
(FWIW, according to this review
http://www.amazon.com/Kindle-Fire-HD...Wi-Fi/product-
reviews/B00CUU1CGY
the KF HDX 7's battery is only 4500 mAh. When plugged into the
wall
with Amazon's fast 9 W charger, it takes about four hours to charge
from 1% to 100%, which means about 1100 mA. Hmm, 9 W / 1.1 A = 8
V.
Does that seem reasonable?

Correction. The charger that came with my KF is 5 W, not 9 W. (I
happened to run across the original box this afternoon, and it lists
the charger among the contents.) So 5 W / 1.1 A = 4.4 V.

Well, you're forcing me to add another piece of information to what I
already said.

Beyond what I said before, you are also assuming that you know that the
energy added to the battery was indeed the 4500mAh that you *think* was
added. You don't know that was true, and you still don't know what the
actual power or current output of the charger was.

Buy yourself one of these:

http://tinyurl.com/no3u4x8

This is a USB voltage and current tester sold on eBay; I bought two
from them and thought them worth the $6.25 (each). They are not HP
instruments from the old days, of course.

Now you can see for yourself all that is going on, within the device's
accuracy.

--
Gene E. Bloch (Stumbling Bloch)

On Sat, 15 Mar 2014 14:40:25 -0700, Gene E. Bloch wrote:

On 3/15/2014, Stan Brown posted:
(FWIW, according to this review
http://www.amazon.com/Kindle-Fire-HD...Wi-Fi/product-
reviews/B00CUU1CGY
the KF HDX 7's battery is only 4500 mAh. When plugged into the
wall
with Amazon's fast 9 W charger, it takes about four hours to charge
from 1% to 100%, which means about 1100 mA. Hmm, 9 W / 1.1 A = 8
V.
Does that seem reasonable?

Correction. The charger that came with my KF is 5 W, not 9 W. (I
happened to run across the original box this afternoon, and it lists
the charger among the contents.) So 5 W / 1.1 A = 4.4 V.

Well, you're forcing me to add another piece of information to what I
already said :-)

Please note the smiley that was restored above ;-)

Beyond what I said before, you are also assuming that you know that the
energy added to the battery was indeed the 4500mAh that you *think* was
added. You don't know that was true, and you still don't know what the
actual power or current output of the charger was.

Buy yourself one of these:

http://tinyurl.com/no3u4x8

This is a USB voltage and current tester sold on eBay; I bought two
from them and thought them worth the $6.25 (each). They are not HP
instruments from the old days, of course.

Now you can see for yourself all that is going on, within the device's
accuracy.

I accidentally left out a smiley above, and really, I *did* intend one
:-)

It's there now...

--
Gene E. Bloch (Stumbling Bloch)

"Gene E. Bloch" wrote in message
...
On 3/15/2014, Stan Brown posted:
On Fri, 14 Mar 2014 13:36:49 -0700, Gene E. Bloch wrote:
BTW, many car websites have PDF manuals available for download. They can
be easier to search than a printed manual :-)


My 2006 Prius came with several hundred pages' worth of manual. A couple
of months ago I had the idea to download the PDF, exactly for easier
searching as you suggest. Toyota didn't have it on one PDF, but one PDF
per chapter. Kind of defeats the purpose if I have to search eight or
nine files!

We have two Toyotae here, and I have almost screamed at some Toyota people
about that.

I did create usable (but slightly askew[1]) manuals by downloading
carefully[2] and then using PDFSAM
http://www.pdfsam.org/ or http://www.pdfsam.org/basic-version/
to merger them.

[1] The internal hyperlinks don't work, and also I couldn't find or figure
how to add some sections, so they are missing.

[2] The first one that I did had two (or more, I forget) sets of manuals
on the site for different releases of the car. Oy wey!

Thanks for this. I haven't needed to merge any PDF files in quite some time,
but I can see a real need for this, and when that need arises, I'll have the
solution :-)
--
SC Tom

"Gene E. Bloch" wrote in message
...
On 3/15/2014, Stan Brown posted:
(FWIW, according to this review
http://www.amazon.com/Kindle-Fire-HD...Wi-Fi/product-
reviews/B00CUU1CGY
the KF HDX 7's battery is only 4500 mAh. When plugged into the wall
with Amazon's fast 9 W charger, it takes about four hours to charge from
1% to 100%, which means about 1100 mA. Hmm, 9 W / 1.1 A = 8 V. Does
that seem reasonable?

Correction. The charger that came with my KF is 5 W, not 9 W. (I
happened to run across the original box this afternoon, and it lists
the charger among the contents.) So 5 W / 1.1 A = 4.4 V.

Well, you're forcing me to add another piece of information to what I
already said.

Beyond what I said before, you are also assuming that you know that the
energy added to the battery was indeed the 4500mAh that you *think* was
added. You don't know that was true, and you still don't know what the
actual power or current output of the charger was.

Buy yourself one of these:

http://tinyurl.com/no3u4x8

This is a USB voltage and current tester sold on eBay; I bought two from
them and thought them worth the $6.25 (each). They are not HP instruments
from the old days, of course.

Now you can see for yourself all that is going on, within the device's
accuracy.

I ordered a couple of these from Amazon:

http://www.amazon.com/gp/product/B00HZA80AA/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

(Hey, 26¢ is 26¢, and by ordering 2, I saved 52¢ LOL!)

I love a good gadget, and this will be very handy, I'm sure. Thanks for the
tip :-)
--
SC Tom

On Sat, 15 Mar 2014 14:40:25 -0700, Gene E. Bloch wrote:
Beyond what I said before, you are also assuming that you know that the
energy added to the battery was indeed the 4500mAh that you *think* was
added.


How do I not know that? Assuming CNet's review was accurate, the KF
battery holds 4500 mAh. At 1%, it was almost completely discharged,
so it would need almost 450 mAh to come back up to 100%. What am I
missing?

Or do you think this is one of those gas-gauge things, where "1%"
doesn't really mean 1%, because the zero point isn't full discharge
but rather the point where the device shuts itself off while it still
has power enough to do so in an orderly way?

As I think about it, I guess that latter does make sense, but surely
the zero point can't be very far above full discharge, so the
distance from 1% to 100% can't be much less than 99% of 4500 mAh.

--
Stan Brown, Oak Road Systems, Tompkins County, New York, USA
http://OakRoadSystems.com
Shikata ga nai...

On Sun, 16 Mar 2014 08:23:46 -0400, SC Tom wrote:

I ordered a couple of these from Amazon:

http://www.amazon.com/gp/product/B00HZA80AA/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

(Hey, 26¢ is 26¢, and by ordering 2, I saved 52¢ LOL!)

I love a good gadget, and this will be very handy, I'm sure. Thanks for the
tip :-)

It makes me a little nervous that it has zero reviews, and that the
wording of the description is identical to this product

http://www.amazon.com/gp/product/B00IF2JGA0

which also has zero reviews.

--
Stan Brown, Oak Road Systems, Tompkins County, New York, USA
http://OakRoadSystems.com
Shikata ga nai...

On Sat, 15 Mar 2014 12:05:44 -0700, Gene E. Bloch wrote:

I did create usable (but slightly askew[1]) manuals by downloading
carefully[2] and then using PDFSAM
http://www.pdfsam.org/ or http://www.pdfsam.org/basic-version/
to merger them.

[1] The internal hyperlinks don't work,

Hmm. I have no experience editing PDFs, but I'm on the lookout for a
way to create a big PDF (about 300 pp) from the HTML chapters of my
textbook at http://www.tc3.edu/instruct/sbrown/swt/ . Having the
internal links work is a must, though.

--
Stan Brown, Oak Road Systems, Tompkins County, New York, USA
http://OakRoadSystems.com
Shikata ga nai...

Stan Brown wrote, On 3/16/2014 9:12 AM:
On Sat, 15 Mar 2014 12:05:44 -0700, Gene E. Bloch wrote:

I did create usable (but slightly askew[1]) manuals by downloading
carefully[2] and then using PDFSAM
http://www.pdfsam.org/ or http://www.pdfsam.org/basic-version/
to merger them.

[1] The internal hyperlinks don't work,

Hmm. I have no experience editing PDFs, but I'm on the lookout for a
way to create a big PDF (about 300 pp) from the HTML chapters of my
textbook at http://www.tc3.edu/instruct/sbrown/swt/ . Having the
internal links work is a must, though.


Html (copied or created or pasted (with formatting including active
valid links) into Word 2010/2013 can create a pdf file retaining link
functionality.




--
...winston
msft mvp consumer apps

On Sun, 16 Mar 2014 09:12:52 -0400, Stan Brown wrote:

On Sat, 15 Mar 2014 12:05:44 -0700, Gene E. Bloch wrote:

I did create usable (but slightly askew[1]) manuals by downloading
carefully[2] and then using PDFSAM
http://www.pdfsam.org/ or http://www.pdfsam.org/basic-version/
to merger them.

[1] The internal hyperlinks don't work,

Hmm. I have no experience editing PDFs, but I'm on the lookout for a
way to create a big PDF (about 300 pp) from the HTML chapters of my
textbook at http://www.tc3.edu/instruct/sbrown/swt/ . Having the
internal links work is a must, though.

The reason the internal links don't work is that many of the links point
to different chapters of the Toyota docs, i.e., to a place in another
named file. So when I combine, they lose their place. The links within a
single component file still work, since they are local links. It's not
the fault of PDFSAM. Or more exactly, PDFSAM hasn't been programmed to
deal with that.

I think it could b done by an industrious programmer, so it might be
worth trying other PDF joiners.

--
Gene E. Bloch (Stumbling Bloch)

On Sun, 16 Mar 2014 08:23:46 -0400, SC Tom wrote:

"Gene E. Bloch" wrote in message
...
On 3/15/2014, Stan Brown posted:
(FWIW, according to this review
http://www.amazon.com/Kindle-Fire-HD...Wi-Fi/product-
reviews/B00CUU1CGY
the KF HDX 7's battery is only 4500 mAh. When plugged into the wall
with Amazon's fast 9 W charger, it takes about four hours to charge from
1% to 100%, which means about 1100 mA. Hmm, 9 W / 1.1 A = 8 V. Does
that seem reasonable?

Correction. The charger that came with my KF is 5 W, not 9 W. (I
happened to run across the original box this afternoon, and it lists
the charger among the contents.) So 5 W / 1.1 A = 4.4 V.

Well, you're forcing me to add another piece of information to what I
already said.

Beyond what I said before, you are also assuming that you know that the
energy added to the battery was indeed the 4500mAh that you *think* was
added. You don't know that was true, and you still don't know what the
actual power or current output of the charger was.

Buy yourself one of these:

http://tinyurl.com/no3u4x8

This is a USB voltage and current tester sold on eBay; I bought two from
them and thought them worth the $6.25 (each). They are not HP instruments
from the old days, of course.

Now you can see for yourself all that is going on, within the device's
accuracy.

I ordered a couple of these from Amazon:

http://www.amazon.com/gp/product/B00HZA80AA/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

(Hey, 26¢ is 26¢, and by ordering 2, I saved 52¢ LOL!)

When I ordered mine on eBay, there were others available for around
$5.99, but I was a good sport and paid the premium price. It makes me
look worthy of the nearby towns of Atherton and Woodside (CA), with all
their Tesla cars.

I love a good gadget, and this will be very handy, I'm sure. Thanks for the
tip :-)

Fact is I rarely use them, but there are times when chargers fail and so
on. Once I learned of them (in a NG) I did as you did. They just
*belong* in a toolbox...

Actually, one good use is to vet a suspicious charger before plugging it
into a device.

--
Gene E. Bloch (Stumbling Bloch)

On Sun, 16 Mar 2014 09:10:50 -0400, Stan Brown wrote:

On Sun, 16 Mar 2014 08:23:46 -0400, SC Tom wrote:

I ordered a couple of these from Amazon:

http://www.amazon.com/gp/product/B00HZA80AA/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

(Hey, 26¢ is 26¢, and by ordering 2, I saved 52¢ LOL!)

I love a good gadget, and this will be very handy, I'm sure. Thanks for the
tip :-)

It makes me a little nervous that it has zero reviews, and that the
wording of the description is identical to this product

http://www.amazon.com/gp/product/B00IF2JGA0

which also has zero reviews.

My review: 4 stars.

The display alternates between voltage and current, the V looks like a
lower case u, and the values fluctuate a bit, thus the one-star penalty.

And I bought my two one at a time :-)

Be aware that I bought the premium one at $6.25; hardly earth shattering
if they are no good.

--
Gene E. Bloch (Stumbling Bloch)

On Sun, 16 Mar 2014 09:00:59 -0400, Stan Brown wrote:

On Sat, 15 Mar 2014 14:40:25 -0700, Gene E. Bloch wrote:
Beyond what I said before, you are also assuming that you know that the
energy added to the battery was indeed the 4500mAh that you *think* was
added.


How do I not know that? Assuming CNet's review was accurate, the KF
battery holds 4500 mAh. At 1%, it was almost completely discharged,
so it would need almost 450 mAh to come back up to 100%. What am I
missing?

You didn't measure it. Nor did they.

Or do you think this is one of those gas-gauge things, where "1%"
doesn't really mean 1%, because the zero point isn't full discharge
but rather the point where the device shuts itself off while it still
has power enough to do so in an orderly way?

You didn't measure it. Nor did they.

As I think about it, I guess that latter does make sense, but surely
the zero point can't be very far above full discharge, so the
distance from 1% to 100% can't be much less than 99% of 4500 mAh.

You didn't measure it. Nor did they.

--
Gene E. Bloch (Stumbling Bloch)

Stan Brown wrote:
On Sat, 15 Mar 2014 12:05:44 -0700, Gene E. Bloch wrote:
I did create usable (but slightly askew[1]) manuals by downloading
carefully[2] and then using PDFSAM
http://www.pdfsam.org/ or http://www.pdfsam.org/basic-version/
to merger them.

[1] The internal hyperlinks don't work,

Hmm. I have no experience editing PDFs, but I'm on the lookout for a
way to create a big PDF (about 300 pp) from the HTML chapters of my
textbook at http://www.tc3.edu/instruct/sbrown/swt/ . Having the
internal links work is a must, though.


It's more like 475 pages.

Like everything in life, the HTML code can have additional
directives added to it, to make automatic traversal by
other tools easier. I used the --webpage directive here, to
just make it eat a linear sequence of files, and maintain
the linkages. It seems to be sorta working.

This is done from Linux. Salt to taste. This is one giant command line
command. It forces your relatively flat site, into one PDF. Pop the
following line into a text editor and remove the excess returns.

htmldoc --no-embedfonts --webpage -f swt.pdf swt/index.html swt/chap00.htm
swt/chap01.htm swt/hwrk01.htm swt/chap02.htm swt/hwrk02.htm swt/chap03.htm
swt/hwrk03.htm swt/chap04.htm swt/hwrk04.htm swt/chap05.htm swt/hwrk05.htm
swt/chap06.htm swt/hwrk06.htm swt/chap07.htm swt/hwrk07.htm swt/chap08.htm
swt/hwrk08.htm swt/chap09.htm swt/hwrk09.htm swt/chap10.htm swt/hwrk10.htm
swt/chap11.htm swt/hwrk11.htm swt/chap12.htm swt/hwrk12.htm swt/hwrkall.htm
swt/chap99.htm swt/hwrk99.htm swt/symbol.htm swt/casesbas.htm swt/ht7.htm
ti83/oops.htm swt/bignames.htm stat/books.htm

The document is 475 pages of PDF. And 7,191,593 bytes.

Your document is not entirely contained in the swt folder. Some
of it jumps out to ti83 folder and stat folder. That forced me to
start above the swt folder, so I could get to the other ones.

I used wget to grab the site, and was lucky my first command was
malformed, so I got more of what I ended up needing.

There are some references created in the file, which actually
cause Acrobat to start a copy of Firefox, and go to your
website. And this could be because of the limitations of me manually
examining your table of contents and making up the command line
from the table of contents. You may need to "neuter" some
of those links in there. Not every link in the doc is "tame".

The HTMLDOC man page has more info on how to modify the HTML
code to make traversal more automatic. Something about
adding H1,H2,H3 headers or something.

Paul