When Dells explode...

Probably battery damage.

isn't that pic from thebroken.org when they put thermite in the battery compartment?

edit: I guess not, but it looks similar to what happened.

I dunno squat about anything, but my buddy at work has to replace his laptop battery due to it's flawed design. He brought this up as an example before I read this. He said the battery was poorly designed so it would expand when heated.

Something not to dissimilar happened with my Motorola mobile phone battery once.

My mobile phone was in my pocket while I was eating lunch and I suddenly noticed my leg getting very warm. I quickly took my mobile phone out of my pocket and could see the back of the case was all swollen up. I took the back of the case off and the battery inside was swelling up right in front of me. It looked like it was about to explode so I ran outside and threw it into a bin and went back to finishing my lunch ...not sure if it exploded or caught fire later on [smile]

I put it down to me somehow short-circuiting the battery cause my keys were in the same pocket ... I'm still not sure though but it definitely always preys on my mind when I'm carrying my mobile phone and I no longer keep my keys or any spare change in the same pocket it is in [cool]

I've heard most of these problems are because of crappy casings on the battery; when the casing busts open the battery guts are exposed to the air and boom.

I dunno if this is true as I know almost nothing about the insides of batteries. Apparently Dell has a whole platoon of these things back at HQ, though.

My coworker told me this:

A battery can be charged to it's peak at ambient temperature.

If the battery is cooled, it "looses" some charge, or inversly, it can hold more charge thus it be charged more.

If the battery is hot, it charges quicker because it holds less overall charge. Inversly, if you use a computer with a cold battery, then warm it up, you will see that the "battery remaining" actually goes up for a while (although the battery charge then goes down more rapidly.

So to make it "explode/burn up", you charge the battery to is peak when it's cool or ambient. Then in the laptop when it heats up, the battery may heat up as well, in effect overcharging the battery because of the gain in temperature. This overcharing effect, along with premature damage on the battery itself will react and cause a chain reaction on the entire battery, especially when exposed to O2. Lithium burns quite well (not as good as magnesium).

This can't happen from a couple once-in-a-while 'very pissed off' laptop slams can it? (where you take a fist, and then just pound once or twice on the palm rests of the laptop)

I just bought a Seagate 7200.10 hard drive, and on the label it says "Warranty void if label removed, or drive is shocked in excess of 350G's".


I was like, "Er, ok."


/Though I'm guessing 350 G's is a lot easier to obtain than I probably think it is...
//I guess I have to put my rocket plans on hold for a little while longer...

Quote:

Original post by Mithrandir /Though I'm guessing 350 G's is a lot easier to obtain than I probably think it is...

It isn't, and if you ever pull it off the status of your harddrive will be the furthest thing from your mind.

CM

Quote:

Original post by Mithrandir /Though I'm guessing 350 G's is a lot easier to obtain than I probably think it is...

Take the acceleration of gravity, and multiply it by 350. 3.4 km/s^2, which is pretty hard to get, unless you were to shoot it out of a particle accelerator or some shit. I dunno how to measure impact force (don't know how many N is 350G).

If you're moving that fast, your organs have been crushed to dust. In any event, I have a Seagate Momentus drive here that says the warranty is void if in excess of 75G, which is still quite a bit.

Quote:

This can't happen from a couple once-in-a-while 'very pissed off' laptop slams can it? (where you take a fist, and then just pound once or twice on the palm rests of the laptop)

Probably not, though that won't help the drive.

Just so you know, a simple tap with a hammer can easily deliver a millisecond's worth of +200 Gs.

350G's is NOT that much because that kind of acceleration will be exceeded by a "hard" object being dropped on a stone or marble floor.

350 G is virtually nothing when talking about deceleration on impact. A drop of approximately 30 cm height of a HDD onto a hard surface generates about 350 G. According to this paper, a drop from only 80cm (ie. from a little over your desk) generates over 1000 G !

The usual 75G certification is pretty ridiculous, if you think about it - that impact deceleration is already generated by a drop from a height of only a few cm !

Quote:

Original post by superdeveloper 350G's is NOT that much because that kind of acceleration will be exceeded by a "hard" object being dropped on a stone or marble floor.

That's what I figured, which is why I dropped the escape clause in there about impact force.