[Arm-netbook] laptop battery lessons...

Discussion:

Luke Kenneth Casson Leighton

2016-12-06 19:01:47 UTC

https://tech.slashdot.org/story/16/12/05/2032203/engineers-explain-why-the-galaxy-note-7-caught-fire#comments

whoops. *sigh*.... so i'll be increasing the laptop's height by 1mm.
argh. that's a big redesign...

l.

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Russell Hyer

2016-12-06 19:05:59 UTC

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Well, that depends. One neat (but silly) tech magazine that publishes
(effectively) only adverts and warnings (regular machines may be
boring or rubbish) published a lovely, glowing review of the galaxy
firestorm (or whatever the actual name is) saying it's great giving
4/5 -- apart from the issue that it melts ;)

Post by Luke Kenneth Casson Leighton
https://tech.slashdot.org/story/16/12/05/2032203/engineers-explain-why-the-galaxy-note-7-caught-fire#comments
whoops. *sigh*.... so i'll be increasing the laptop's height by 1mm.
argh. that's a big redesign...
l.
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Julie Marchant

2016-12-06 19:13:05 UTC

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Does the laptop housing have the same design flaw? That's a stunning
coincidence.

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Russell Hyer

2016-12-06 19:26:59 UTC

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Well, it's a lucky catch.

@Luke, as to tolerances, will you match the tolerances as described by
the expert report, or will you adjust and add an additional tolerance
on top?

R

Post by Julie Marchant

Does the laptop housing have the same design flaw? That's a stunning
coincidence.
--
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https://onpon4.github.io
https://emailselfdefense.fsf.org
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Luke Kenneth Casson Leighton

2016-12-06 21:01:24 UTC

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Post by Russell Hyer
Well, it's a lucky catch.
@Luke, as to tolerances, will you match the tolerances as described by
the expert report, or will you adjust and add an additional tolerance
on top?

6mm + 10% => 6.6mm - i'm adding 1.0 so 7mm.

l.

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Luke Kenneth Casson Leighton

2016-12-06 21:00:40 UTC

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Post by Julie Marchant

Does the laptop housing have the same design flaw?

the battery is radically different: it's an e-bike battery, it's
going to be robust as hell (capable of delivering far more than what
is being asked of it), so it's simply not going to be made of layers
as thin as the samsung battery...

... also bear in mind that the base is wood: it would flex...

... but i still don't wish to take any risks, so i'll be increasing
the base height by 1mm. it's a single parameter (i've adjusted it
before) but i still have to do a thorough review / walk-round in the
CAD. and re-print everything. *sigh*.

l.

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Julie Marchant

2016-12-06 22:04:42 UTC

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Post by Luke Kenneth Casson Leighton
the battery is radically different: it's an e-bike battery, it's
going to be robust as hell (capable of delivering far more than what
is being asked of it), so it's simply not going to be made of layers
as thin as the samsung battery...
... also bear in mind that the base is wood: it would flex...
... but i still don't wish to take any risks, so i'll be increasing
the base height by 1mm. it's a single parameter (i've adjusted it
before) but i still have to do a thorough review / walk-round in the
CAD. and re-print everything. *sigh*.

Then it sounds like you don't have anything to worry about. Keep in
mind, Samsung's whole debacle came about because they were trying to
hard to squeeze as much battery life as possible into the phone.

Also, consider the OpenPandora, which has a design that actively
requires some amount of pressure to be on the battery at all times
because of how the connector works.

Actually, are you even using a LiPo battery? Plain Li-ion batteries are
rigid and don't have this problem.

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Luke Kenneth Casson Leighton

2016-12-06 22:30:42 UTC

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Post by Julie Marchant

Then it sounds like you don't have anything to worry about. Keep in
mind, Samsung's whole debacle came about because they were trying to
hard to squeeze as much battery life as possible into the phone.
Also, consider the OpenPandora, which has a design that actively
requires some amount of pressure to be on the battery at all times
because of how the connector works.

i'll be soldering wires onto the tabs (they're enormous: about 20mm x
30mm). with an inline 6A fuse.

Post by Julie Marchant
Actually, are you even using a LiPo battery? Plain Li-ion batteries are
rigid and don't have this problem.

just reading the datasheet... Lithium Ion (LiCoMn)

should be here:

http://hands.com/~lkcl/eoma/laptop_15in/EV%20GPNCM62135160%2010Ah%20NiCoMn%20battery%20cell.pdf

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c***@sasktel.net

2016-12-07 17:07:02 UTC

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The "URL" says <NiCoMn> as Nickel, not <LiCoMn> as Lithium.
Which is right?
~~~~~

Post by Luke Kenneth Casson Leighton

Post by Julie Marchant
Actually, are you even using a LiPo battery? Plain Li-ion batteries are
rigid and don't have this problem.

just reading the datasheet... Lithium Ion (LiCoMn)
http://hands.com/~lkcl/eoma/laptop_15in/EV%20GPNCM62135160%2010Ah%20NiCoMn%20battery%20cell.pdf

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Adam Van Ymeren

2016-12-07 17:21:14 UTC

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Post by c***@sasktel.net
The "URL" says <NiCoMn> as Nickel, not <LiCoMn> as Lithium.
Which is right?

The PDF that the URL links to says:

"Li-ion(NiCoMn) Polymer Battery Cell Specification"

So its a lithium ion nickel polymer battery? Haha I have no idea what
I'm reading.

Post by c***@sasktel.net
~~~~~

Post by Luke Kenneth Casson Leighton

Post by Julie Marchant
Actually, are you even using a LiPo battery? Plain Li-ion batteries are
rigid and don't have this problem.

just reading the datasheet... Lithium Ion (LiCoMn)
http://hands.com/~lkcl/eoma/laptop_15in/EV%20GPNCM62135160%2010Ah%20NiCoMn%20battery%20cell.pdf

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Denis 'GNUtoo' Carikli

2016-12-08 08:44:45 UTC

Permalink

On Tue, 6 Dec 2016 19:01:47 +0000

The root of the article is a blog post[1] by a company specialized in
finding and fixing such issues, where they analyzed the issue by
buying and taking apart a Galaxy Note 7.
The article also heavily try to promote the services that this company offers.

The information was then picked by a review magazine that wrote a
journalistic article[2] with that information.

The journalistic article was then picked by slashdot.

It would probably be wiser to ask battery experts before taking any
decision, since:
- That company tried to promote their services.
- They don't point to documentation or information on the margin they
refer to.
- The battery technology is probably different on the EOMA laptop.
- The casing is probably different too.
- That laptop will probably be used for a time that is way longer than
the average use time for consumer smartphones.
- The average customers for common smartphones don't mess with them,
open the device, access the PCB, etc...

What if, for instance:
- You need more space than the 10% figure they mentioned? You probably
don't want to redesign it twice, and you probably don't want to make
unsafe laptop either, especially because they will probably be used
for a very long time by people messing with them.
- You don't need to redesign the laptop because the problem doesn't
apply it.

References:
-----------
[1]https://www.instrumental.ai/blog/2016/12/1/aggressive-design-caused-samsung-galaxy-note-7-battery-explosions
[2]http://www.digitaltrends.com/mobile/instrumental-galaxy-note-7-teardown-news/

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Russell Hyer

2016-12-10 20:05:22 UTC

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Hi,

I wonder if Vauxhall (UK's division of General Motors (or these days,
general unexplained electrical fires...)) has any lessons for
electrical wiring in computers. True, cars aren't exactly computers.
But these days they're all wired like a computer and contain several
just behind the dash. (And also, it's true that Vauxhall hasn't really
released much info, but it's still something to watch, but perhaps it
only occurs if / when companies are cutting corners to save a buck and
General Motors is generally a company to which that way of working
applies)

Russell

Post by Denis 'GNUtoo' Carikli
On Tue, 6 Dec 2016 19:01:47 +0000

The root of the article is a blog post[1] by a company specialized in
finding and fixing such issues, where they analyzed the issue by
buying and taking apart a Galaxy Note 7.
The article also heavily try to promote the services that this company offers.
The information was then picked by a review magazine that wrote a
journalistic article[2] with that information.
The journalistic article was then picked by slashdot.
It would probably be wiser to ask battery experts before taking any
- That company tried to promote their services.
- They don't point to documentation or information on the margin they
refer to.
- The battery technology is probably different on the EOMA laptop.
- The casing is probably different too.
- That laptop will probably be used for a time that is way longer than
the average use time for consumer smartphones.
- The average customers for common smartphones don't mess with them,
open the device, access the PCB, etc...
- You need more space than the 10% figure they mentioned? You probably
don't want to redesign it twice, and you probably don't want to make
unsafe laptop either, especially because they will probably be used
for a very long time by people messing with them.
- You don't need to redesign the laptop because the problem doesn't
apply it.
-----------
[1]https://www.instrumental.ai/blog/2016/12/1/aggressive-design-caused-samsung-galaxy-note-7-battery-explosions
[2]http://www.digitaltrends.com/mobile/instrumental-galaxy-note-7-teardown-news/
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