Author Topic: EEVblog #822 - World's Worst Tablet Computer Teardown  (Read 54398 times)

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Online Cyberdragon

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Re: EEVblog #822 - World's Worst Tablet Computer Teardown
« Reply #150 on: December 06, 2015, 06:05:59 am »
It was the 11th one that happened to not spontaniously explode when charged. It looks like it was built by chinese children out of salvaged parts. It's probably either a white van scam or something homemade because someone needed a tablet, like now...like right now, so they built one out of stuff lying around and used a blowtorch to solder.
*BZZZZZZAAAAAP*
Voltamort strikes again!
Explodingus - someone who frequently causes accidental explosions
 

Offline Godzil

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Re: EEVblog #822 - World's Worst Tablet Computer Teardown
« Reply #151 on: December 06, 2015, 01:02:19 pm »
Just the screen and the ITX (or whatever the format) PC board would be interesting to keep!
When you make hardware without taking into account the needs of the eventual software developers, you end up with bloated hardware full of pointless excess. From the outset one must consider design from both a hardware and software perspective.
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Offline CatalinaWOW

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Re: EEVblog #822 - World's Worst Tablet Computer Teardown
« Reply #152 on: December 21, 2015, 03:24:43 pm »
In my hometown, a large but not very developed Chinese city, almost every bare cell seller in both of the 2 major electronics markets, offers spot welding and cell packing service.

Anyway, an improper, just work, transformer style spot welder costs <$100 if bought online, and can be build <$5 from a broken microwave oven.

Here in the US you can find this service in very modest size cities.  Batteries+ does it for example.  But not rapidly.  I have had a several day wait.  They just don't have enough of the business to staff the service full time, or to provide very much capacity.  So if the guy who runs the welder is out, or if a local contractor just came in and got all of the batteries for his portable tools redone you have a long delay.  Same story for the welder.  Cheap, but by the time FedEx delivers it the weekend is gone.
 

Offline drussell

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Re: EEVblog #822 - World's Worst Tablet Computer Teardown
« Reply #153 on: December 21, 2015, 05:14:14 pm »
Here in the US you can find this service in very modest size cities.  Batteries+ does it for example.  But not rapidly.  I have had a several day wait.

Try Interstate Batteries if you have one of them near you.  The one here will custom build or rebuild a pack while you wait and their cells are top quality (as are their lead-acid automotive batteries, etc.  Great batteries!)

Personally, I usually just do it myself and just solder them (use a hot and fast iron or a gund) even though I have equipment that could be used to spot weld them.  Hardwiring and soldering leads to a standard / alkaline battery was proper standard procedure in most VTVMs back in the day (power for the resistance ranges.)  There's really nothing wrong with soldering to batteries as long as you do it correctly :)

 

Online f4eru

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Re: EEVblog #822 - World's Worst Tablet Computer Teardown
« Reply #154 on: December 21, 2015, 06:29:39 pm »
There's really nothing wrong with soldering to batteries as long as you do it correctly :)
:palm: :palm: :palm: :palm: :palm: :palm:
Of course it's WRONG !! it's very dangerous !!
Under the plus pole nipple or each and every rechargeable cell sits an overpressure valve (this is why there are holes in it)
when you solder on the nipple, the pressure valve seal material gets overheated, and melts.
Often, the valve then sticks, which is very dangerous, the battery can explode if treated wrong, instead of making a controlled electrolyte release !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!  :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm:


The right way to do it is to use a spot welder for batteries, and zinc strips. You can get very cheap chinese ones from the usual sources.
Alternatively, get batteries with tabs, and solder the tabs ! That's safe, as long as the tab edges don't rub against the isolating sleeves of the batteries.
« Last Edit: December 21, 2015, 06:33:11 pm by f4eru »
 

Offline gildasd

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Re: EEVblog #822 - World's Worst Tablet Computer Teardown
« Reply #155 on: December 21, 2015, 07:51:07 pm »
There's really nothing wrong with soldering to batteries as long as you do it correctly :)
:palm: :palm: :palm: :palm: :palm: :palm:
Of course it's WRONG !! it's very dangerous !!
Under the plus pole nipple or each and every rechargeable cell sits an overpressure valve (this is why there are holes in it)
when you solder on the nipple, the pressure valve seal material gets overheated, and melts.
Often, the valve then sticks, which is very dangerous, the battery can explode if treated wrong, instead of making a controlled electrolyte release !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!  :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm:


The right way to do it is to use a spot welder for batteries, and zinc strips. You can get very cheap Chinese ones from the usual sources.
Alternatively, get batteries with tabs, and solder the tabs ! That's safe, as long as the tab edges don't rub against the isolating sleeves of the batteries.
I agree.
Our uni makes it own custom LI-Ion battery packs for solar boat racing.
We use a the pedal spot welder picked off a junk heap somewhere and it works great.
I'm electronically illiterate
 

Offline MartinHocking

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Re: EEVblog #822 - World's Worst Tablet Computer Teardown
« Reply #156 on: February 22, 2016, 03:28:22 am »
Yes I have seen jobs like that before, and even done stuff like that when I was younger lol. anyway what do you do with it after tear down ?? I may have a use for it after a REBUILD ?. anyway keep up the good work love the videos.
 

Offline Warhawk

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Re: EEVblog #822 - World's Worst Tablet Computer Teardown
« Reply #157 on: February 22, 2016, 10:04:24 pm »
There's really nothing wrong with soldering to batteries as long as you do it correctly :)
:palm: :palm: :palm: :palm: :palm: :palm:
Of course it's WRONG !! it's very dangerous !!
Under the plus pole nipple or each and every rechargeable cell sits an overpressure valve (this is why there are holes in it)
when you solder on the nipple, the pressure valve seal material gets overheated, and melts.
Often, the valve then sticks, which is very dangerous, the battery can explode if treated wrong, instead of making a controlled electrolyte release !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!  :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm: :palm:


The right way to do it is to use a spot welder for batteries, and zinc strips. You can get very cheap chinese ones from the usual sources.
Alternatively, get batteries with tabs, and solder the tabs ! That's safe, as long as the tab edges don't rub against the isolating sleeves of the batteries.

Tell it to the R/C modelers ;-). Experienced guys would never use spot welded battery packs. Especially those attending competitions or having their toys a bit "professional". I've soldered a lot of battery packs without any failure. Of course I killed few cells on the beginning. ::)

I admit that R/C modelers are bit crazy... I've seen really crazy stuff over years, e.g. "human delta peak" charging for famous Sanyo 1700 SCR....

In general, you are right and people with no experience should not try to solder any cells, but with your thousand face palms you are overreacting.

« Last Edit: February 22, 2016, 10:08:02 pm by Warhawk »
 

Offline Fungus

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Re: EEVblog #822 - World's Worst Tablet Computer Teardown
« Reply #158 on: February 23, 2016, 05:35:00 am »
I've soldered a lot of battery packs without any failure. Of course I killed few cells on the beginning. ::)

So.... you haven't soldered a lot of battery packs without failure.

And the ones that "survived", how do you know they aren't damaged?
 

Offline Warhawk

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Re: EEVblog #822 - World's Worst Tablet Computer Teardown
« Reply #159 on: February 23, 2016, 07:48:59 am »
I've soldered a lot of battery packs without any failure. Of course I killed few cells on the beginning. ::)

So.... you haven't soldered a lot of battery packs without failure.

And the ones that "survived", how do you know they aren't damaged?

Come On ... my battery packs have been working for years...

Here is an example of the soldering process example:
http://www.lomcovak.cz/dilna/old/baterky.htm

(translate from Czech to English or just go through the pictures).
There are of course other alternate ways (soldering side by side).
« Last Edit: February 23, 2016, 07:50:41 am by Warhawk »
 

Offline mux

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Re: EEVblog #822 - World's Worst Tablet Computer Teardown
« Reply #160 on: February 23, 2016, 08:07:42 am »
If you solder it well, there won't be any measurable damage on the inside. Lithium ion will fail under heat stress through:
  • Ion reduction (long-term heat, arrhenius effect, +10C = 2x faster ageing)
  • Thermal runaway (140-170C)
  • Thermal dissociation of e.g. the electrolyte

When soldering the cathode, which is connected both electrically and thermally to the entire outside of the battery, it's extremely hard to introduce enough heat into the battery to cause any of the failure modes. You'd have to be heating it for minutes to get anywhere near dissociation or runaway, and even then you don't have any current through the battery to kickstart the runaway reaction. Mind you, lithium ion doesn't use water-based electrolytes. There is no pressure build-up at any time, unless if you're producing hydrogen during thermal runaway.

On the anode, you're generally not directly thermally connected to anything but the carbon/polymer rod, so 1) you'll be done in seconds, way too little time to introduce any significant amount of heat into the pack and 2) you have very bad thermal contact to the sensitive bits, so I doubt if you can even get the electrolyte past 100C

Spot welding is not necessarily better than soldering. The reason cells are spot welded is simply because it's economical, however you don't get a particularly low resistance weld. The actual welded area is only a few mm2, good enough for laptop battery packs that never go above 1A discharge, but not nearly enough for high-current applications like RC stuff. Soldering is best practice in this case, and if you half know what you're doing it's not going to impact longevity at all for any practical purposes.

Hell, up to a few years ago most high-end electric tool manufacturers used special high-copper solder to build their packs (instead of spot welding). Now that surface welding has matured they've moved over to that, but that should say a lot.
 

Offline Warhawk

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Re: EEVblog #822 - World's Worst Tablet Computer Teardown
« Reply #161 on: February 23, 2016, 08:12:32 am »
You are right that I used misleading statement. It should have been :"I've soldered a lot of battery packs without any failure after I learnt how to do that".

Btw there is a small business in Olomouc (http://www.satria.cz/ ) where a guy makes new battery packs or refurbishes them for various handtools e.g. drills, screwdrivers etc. As far as I know he has been been in the business for years and became famous in the community for his quality. He uses soldering as well.
Another guy (working now at ON Semi in Roznov) made for him several "ProForms" http://tichytomas.info/clanek.php?id=23 which he uses for battery checks....

R/C aficionado is not always a kid with his foam toy in a park ;-)

Offline Arlen Moulton2

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Re: EEVblog #822 - World's Worst Tablet Computer Teardown
« Reply #162 on: March 01, 2016, 07:13:55 am »
That strange pattern on the display looks just like the displays we used at a company I used to work for. IIRC, they were a ruggedized, hardened glass projected-capacitance touch panel, designed for industrial applications where the operator needed to use the touchscreen while wearing gloves. I think they were made by a company called Zytronic. That display might be a similar type.

I've seen it on ATMs as well.
it is because of the capacitive touch display. They are so bad.
amoulton
 

Offline Fungus

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Re: EEVblog #822 - World's Worst Tablet Computer Teardown
« Reply #163 on: March 01, 2016, 09:33:47 am »
That strange pattern on the display looks just like the displays we used at a company I used to work for. IIRC, they were a ruggedized, hardened glass projected-capacitance touch panel, designed for industrial applications where the operator needed to use the touchscreen while wearing gloves. I think they were made by a company called Zytronic. That display might be a similar type.

I've seen it on ATMs as well.
it is because of the capacitive touch display. They are so bad.

They do the job they're designed for.

Obviously they'd be unacceptable on an iPad, but for something industrial or something that people use for a couple of minutes? Not a problem.

 


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