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Several weeks ago, I noticed a swollen lithium-ion battery in an older MacBook laptop. Substantial swelling, the battery looks almost twice as thick as normal near one corner. I initially noticed the swelling because it deformed the bottom plate of the laptop. Since then, I have not used the device and currently am storing it in a fire safe location. Unfortunately, the battery is screwed in place inside the laptop and I initially worried that unscrewing might cause further damage or put pressure on the battery. Now, that it has been a while since I noticed the damage to the battery, I assume that it has discharged substantially (though the state of charge was unknown at the time of failure).

Is this assumption safe to make? Can I expect that the danger of fire is lower after safely storing it for this period of time and not observing any changes? Do you think that there is still danger in unscrewing and removing the battery? How cautiously should I need to handle the battery?

  • Discharging the battery by operating the Macbook is probably a good idea.| Once it is as discharged as you can reasonably make it, - As JimmyB says , removing it with sensible care is probably the best idea. – Russell McMahon Jun 21 '19 at 14:49
  • I did not consider manually discharging the battery because I expected it to be more dangerous than just letting it sit without a current. So would you consider powering it on to see if there is still enough voltage from the cells to power the computer? Or is there another (safer) way to slowly discharge? – user73014 Jun 21 '19 at 16:06
  • @user73014 How much swelling? A amount of moderate swelling is acceptable for a lithium battery. A photo might help here. – Nick Alexeev Jun 21 '19 at 23:22
  • @user73014 Discharge by turning the computer on probably will not cause problems (nothing in life is certain). IF you have access to the terminals you could use a suitably low-current load BUT I personally would be happy to carefully and sensibly dismantle the system and remove the battery. It is more likely than not that the battery swelling is not a very major hazard, but it is best to eliminate the possibility than to risk the PC's (and your) safety. – Russell McMahon Jun 22 '19 at 0:12
  • @RussellMcMahon Not sure if having any current flow through the battery is actually a good idea. Sounds like more risky than just removing the battery to me. – JimmyB Jun 22 '19 at 0:42
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Can I expect that the danger of fire is lower after safely storing it for this period of time and not observing any changes?

No. It may already be deeply discharged, or it may be 50% full. No way to tell from "the state of charge was unknown" and "it has been a while".

Do you think that there is still danger in unscrewing and removing the battery?

No. A battery is not nitroglycerin. Moving it without bending or pressing on it is safe. I'd say that it probably can be removed from the device without significant mechanical stress, so the 'risk' depends on how careful you are. You already know that you don't want to apply force to the battery in the process, but I believe you won't have to.

I feel that the risk of letting it sit where it is is much higher than removing and securing it a.s.a.p. If it starts to burn right now, at least the MacBook will burn too, so get rid of the battery as soon as you can.

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  • Just want to make sure Russell McMahon's comment stays near this answer: run the battery down as low as possible before removing. Furthermore, make sure you do not short the battery terminals...doing so would make removing the battery much more dangerous than leaving it in place. – Elliot Alderson Jun 21 '19 at 15:13
  • A swollen battery means at least one cell has 'out-gassed', But the other cells in the battery will still hold their charge. An out gassed cell is not all that dangerous, it has already passed its failure state without 'venting with flame'. It should be entirely safe to run it down in the laptop before removing. – hekete Jun 22 '19 at 4:30
  • @jIMMYb We are not in disagreement. I'd have expected he'd have looked at our mutual device and taken one or other course (predischarge using laptop then remove, or just remove.) I've encouraged him to GET IT OUT. You may wish to do so too. – Russell McMahon Jun 28 '19 at 12:07
  • @RussellMcMahon Did it now by bold-ing the last phrase of my answer :) – JimmyB Jun 28 '19 at 12:39

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