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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 enti

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.

lmilcin 6y ago
It is not normal aging progression. 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.
- jacquesm 6y ago
  Yes, it is perfectly normal when not compressed. 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.
  - lmilcin 6y ago
    I only wish you don't get your flat/home burned up due to faulty battery because of your misconception and that others will ignore it. Again, never, under any circumstances, try to charge a swollen laptop battery. https://www.howtogeek.com/244846/what-to-do-when-your-phone-or-laptop-has-a-swollen-battery/ https://www.howtogeek.com/244846/what-to-do-when-your-phone-...
    - jacquesm 6y ago
      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. https://www.coolbuster.net/2010/12/wakemate-fire.html https://www.coolbuster.net/2010/12/wakemate-fire.html 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. From: https://www.rchelicopterfun.com/puffed-lipo.html https://www.rchelicopterfun.com/puffed-lipo.html "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.
jacquesm 6y ago
This is spot on.

lmilcin 6y ago

It is not normal aging progression. 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.

jacquesm 6y ago
Yes, it is perfectly normal when not compressed. 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.
- lmilcin 6y ago
  I only wish you don't get your flat/home burned up due to faulty battery because of your misconception and that others will ignore it. Again, never, under any circumstances, try to charge a swollen laptop battery. https://www.howtogeek.com/244846/what-to-do-when-your-phone-or-laptop-has-a-swollen-battery/ https://www.howtogeek.com/244846/what-to-do-when-your-phone-...
  - jacquesm 6y ago
    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. https://www.coolbuster.net/2010/12/wakemate-fire.html https://www.coolbuster.net/2010/12/wakemate-fire.html 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. From: https://www.rchelicopterfun.com/puffed-lipo.html https://www.rchelicopterfun.com/puffed-lipo.html "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.

jacquesm 6y ago

This is spot on.