I had an MBP whose battery swelled up so large that it was pusuhing the Touchpad out of its seat. I was pretty alarmed when I found the cause, worried the thing might blow up on me. But from what I read at the time, it actually is the (or, at least, a) normal progression of the battery.
It is normal aging progression of a battery that is not compressed inside a rigid container. In electric vehicles, a constant and firm compression over the entire face of the cell, stops this from occurring [1]. It does not look like a compression plate was incorporated into the design.
Source: design engineer for EV company.
1: The compression is most commonly about 70kPa, but varies by manufacturer recommendations. Some manufacturers lately have started to recommend not to compress their cells because they have solved the swelling in other ways.
Think about this, do you think laptop designers designed laptop to expand with the laptop? No, I don't think so. While there might be a tiny bit of space allowance I have never seen a laptop that has been designed to "grow" with its battery.
Not every swollen battery is a bomb that is going to blow, but do you really want to risk it? You have no way of determining whether it is safe to use or not and for this reason you need to treat is as unsafe.
Your 'think about this' asks someone to do this for a living to think about something that they are likely thinking about it every day of their working life.
Yes, laptop designers - and designers of all high density consumer packaged batteries - are designing their cases with battery aging in mind. In fact this is such an important point we explicitly check for it during evaluation of companies that produce such hardware because if this isn't done carefully it is a safety risk.
Laptops aren't designed to 'grow' with their battery, that's just a strawman you made up. The choices are:
- leave the battery some room in the case so that its normal life expansion can be accommodated (the battery enclosure will have to be flexible for this to work properly)
or
- design the enclosure in such a way that the battery is situated so that it can not expand at all.
Batteries do not actually have to swell and indeed, not every swollen battery is bad, in fact this may well be calculated in during the design phase. So yes, you will 'risk it', it being perfectly ok.
> You have no way of determining whether it is safe to use or not and for this reason you need to treat is as unsafe.
We actually do. It's called materials science and accelerated aging as well as learning from past mistakes. Engineering is the accumulated knowledge of many 1000's of failed experiments coupled with rigorous research into the materials used for engineering themselves, chance is minimized as much as possible.
@jacquesm: I can't reply to your post, so do it here:
Even assuming you do know what you are doing, it is still very irresponsible to tell this to people who will have no way to make use of the knowledge safely.
When somebody has their expensive laptop swollen they have incentive to delude themselves it is ok. It is not and it is dangerous. There is no way to tell the reason the battery is swollen and so the thing they should do is to not charge the battery and get it replaced.
You're fearmongering all over this thread. Stop digging, you are at hobbyist level with your knowledge on a forum with professionals. if you can't tell the difference between 'batteries will swell some during their operating life' vs 'excessive swelling is a sign things are about to go pear shaped' then you shouldn't be working on your own laptop period.
Any laptop older than 12 months will have a slightly swollen battery (even if that swelling is accommodated by the case immediately around the battery so you won't see it).
HN stands for 'hacker news', if batteries scare you then don't use them. The same goes for powertools, explosives, household cleaning products, chisels, hammers and so on. Danger is a relative thing. Knowing the head fire marshall of a very large (2 million inhabitants) European city: if you are afraid of fire then you should disconnect all your wall-warts. Those are the cause of a very large number of fires and the best way to deal with them is to switch them all off when you leave your home. Batteries are a very distant second to that and stories of them catching fire are rare enough that they make the news. See also: Samsung and Boeing.
Note that a perfectly good battery can go into thermal runaway in a couple of seconds if mistreated, the amount of energy these pack is very impressive and if that energy is released quickly then the results can be catastrophic, even resulting in the hull-loss of airliners if the combination of circumstances is particularly bad:
Did you even read the text of that link? In case you didn't:
"Apple carries out a number of iPhone repairs in-store these days, but there is one fault that stores are forbidden from touching, and that’s swollen batteries.
There’s just too high a risk that these will be accidentally punctured during disassembly or removal, and a video of a DIY attempt at replacing a swollen battery in an iPhone 5s provides a graphic illustration of this…
Reddit user tryagainin47seconds posted a video of a coworker attempting to dismantle an iPhone, which burst into flames. The most likely explanation is that the man punctured the battery.
The battery itself appears to have been third-party[+].
Battery had been replaced by coworker who originally owned the phone and he thinks it was faulty equipment. Battery was swelling up when I charged it and he was taking it apart to see what was going on."
[+] -> this is a pretty important detail and my indicate a battery that was not matched well to the charge circuitry leading to an accelerated degradation and/or outright destruction of the cells.
Which pretty much confirms just about everything I wrote above modulo some edge cases that this particular instance did not cover.
Batteries that have swollen outside their design parameters are a lot more risky than those that have not, and that clearly was the issue here.
And it does not say anywhere in that article that 'swollen batteries are not to be used', though - again - you'd be pretty dumb to use batteries that have a pillow shape indicating significant gas development has occurred which most likely has all kinds of negative effects on the state of the laminations and the batteries' ability to keep a charge. But a battery that has expanded a bit can be perfectly safe to operate assuming it is still within design parameters.
Anyway, I'm done with your name calling, have a really nice day and enjoy your safe life without any Lithium tech. Because swell they will, whether you like it or not.
Some more interesting links for people interested in battery tech:
Thank you, I'm perfectly ok and actually know what I'm doing. Your fears are misplaced. Batteries are - as long as the design is proper and the charge requirements are met - reasonably safe.
Given that we have many 100's of billions of them in operation and that there are not that many reports of spontaneous combustion is good proof of that.
Dead batteries are murdered, they don't die of their own accord.
What kills batteries and may cause them to misbehave:
- overheating
- overcharging
- repeatedly deep discharging
- short circuiting
- puncturing
- deformation of the container
- poor enclosure design
- shock loads (usually in combination with poorly designed mounts such as wrap around straps on heavy batteries)
Other than that you should be perfectly fine. Your concern is appreciated but the misconception is on your end, keep in mind that I do tech DD for a living and I'm quite familiar with the literature regarding battery safety, medical devices and other on the body devices using LiPo and other high density batteries are commonplace now and everybody is trying to work hard to avoid being the next Wakemate.
The examples listed in your linked article are all way past the design limits and obviously there is no point in even attempting to continue to use a battery like that and in fact poses significant risk. But that does not contradict anything I said: high density batteries tend to expand a bit over their design life. If you don't want to accept that that is fine with me, but maybe then you should stop using such batteries altogether.
"As we just found out, LiPo cells can & will swell. It's actually somewhat normal as they age since electrolyte decomposition is occurring all the time. The speed at which it occurs, and if excess O2 or CO2 is released, is based on many factors including how hard you run (discharge) the packs, how fast you charge them, how you store them, their age, the quality of the packs, and of course how much they heat up during use."
Which is a pretty correct summary of the reality of operating such high energy density batteries.
Typical battery chemistry involves a step that may produce some gas and this is perfectly normal. Because gas occupies more volume than the solid the gas came out of the battery geometry will change and because the charge/discharge cycle isn't perfect over time you may have a build up of some gas. This is why the battery 'sleeve' is a bit elastic and very strong. In fact, that's the whole reason they puff up in the first place, if the sleeve were porous or had an overpressure vent then the swelling would not happen. Too much swelling is a sign a battery is end-of-life and should be replaced. As a good rule of thumb: if the battery is outside of its designed space or geometric limit then the swelling is excessive, in other words, if it touches stuff that it would not normally touch when it was still new then it should be discarded.
If you want to be nice to your batteries: keep the charge/discharge cycle between 95 and 50% or so, ensure they are well ventilated, if there is any sign of overheating stop charging, never ever puncture a high density battery and if you ever drop the gear the battery is in inspect the battery before charging it again. Do not short-circuit or overload a battery, they have super low internal resistance and will be more than happy to outgass so fast if you do that the enclosure may blow up, worst case you will induce thermal runaway with all of the consequences that go with it.
