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My 3.5 year old laptop is suffering from a swollen battery despite having completed only 100 cycles. It's been plugged in for at least 18 months, which I read likely contributed to its degradation.

I'm going to get it repaired but would like to take steps to prevent / delay this from happening again.

According to this article the 'optimum' charge for a Li-ion battery is 40%-80%, but more generally the advice seems to be to avoid leaving your laptop permanently plugged in.

One approach could to be plug the laptop into the mains through a simple timer, which could cut the power from 00:00 - 12:00, so that each day from when I switch the laptop on at 09:00 to 12:00 the battery would drain and then be recharged.

Aside from any performance issues of the laptop running on battery v.s. mains power, are there any drawbacks to this approach, and could I reasonably expect an improvement in the lifespan of the battery? Any advice on timing schedules - I could set the timer weekly rather than daily, for example - also appreciated.

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  • \$\begingroup\$ I think swollen is bad news, swollen batteries can go bang, batteries shouldn't swell and if they are swollen they're already dead... I think? \$\endgroup\$ – user253751 Mar 19 at 11:20
  • \$\begingroup\$ Funnily enough the system reports that the condition of the swollen battery is 'normal' and it still seems to work reasonably well on battery power. But yes, I'll be getting it replaced asap. Looking to extend the life of the replacement battery \$\endgroup\$ – Matt Saunders Mar 19 at 11:25
  • \$\begingroup\$ (though I notice that modern Macbooks are very thin, so perhaps it only takes a tiny amount of swelling to break the touchpad; I wouldn't imagine a very slightly swollen battery was in immediate danger of going bang) \$\endgroup\$ – user253751 Mar 19 at 11:35
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Do you actually need to run the laptop not plugged in? Is it an option to simply plug it in when you're using it or have the timer run for that period of time?

A 12 hour charge is likely to at least somewhat overcharge the battery, so you may wish to run it dead and see how long a full charge actually takes. My laptop charges fully in about 1 hr and 45 minutes and it's nothing special. I would think a modern laptop would only apply a periodic topping charge to a fully charged battery and that leaving it plugged in would produce few issues, but if it is damaging itself, yes, limiting overcharge time will increase battery life somewhat. Outdoor block heater timers come to mind. They're about $20 where I live and you can control the power cycle over the full day in 15 minute increments by flipping little tabs.

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  • \$\begingroup\$ Useful input thanks and yes that's the kind of timer I was thinking about. It feels like a balancing act - a low number of charge cycles is bad for the battery (apparently), but so is a high number of charge cycles. I'm just looking to strike the middle ground with a solution I can implement and then forget about \$\endgroup\$ – Matt Saunders Mar 19 at 11:23
  • \$\begingroup\$ If you're sure of the times of day you'll be using it and it's between 60 and 80% charge by the time you're done, you could protect it slightly more even by having it charge a bit before you use it instead of after you use it. For long term storage just over half charge charge and just under 20 degrees C is ideal. \$\endgroup\$ – K H Mar 19 at 11:30
  • \$\begingroup\$ Ah good idea - thanks! \$\endgroup\$ – Matt Saunders Mar 19 at 11:32

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