Charging a lithium battery to 80% only?

Re:Charging a lithium battery to 80% only? by venj on Tuesday November 21, 2023 @04:35AM (#38361442)

I think a lot of laptops do this because their cooling system is too weak for the CPU.

The Lenovo Thinkpad t480s comes to my mind: with factory settings, the CPU was unable to reach its advertised boost frequency nor maintain its max non-boost frequency for more than a few minutes. After 5 to 10 minutes, the machine was usually running at 300/400mhz under its advertised clock speed.

Undervolting helped a lot but could not fix the issue completely, under clocking was the only solution to maintain a consistent clock speed.

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Re:Charging a lithium battery to 80% only? by sgarland on Tuesday November 21, 2023 @07:49AM (#38362953)

IMO, at least with x86, there is a point where it simply doesn’t make sense to cram higher clocks into a laptop. The last Intel MBP could be had with an i9, and IME if you left turbo enabled, even at idle the fans were annoyingly loud. If you pushed it, you’d get a quiet jet engine as they struggled to keep temps just below 95 C.

It was usually less annoying for me to just disable turbo, and only turn it on if I really needed the boost.

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Re:Charging a lithium battery to 80% only? by Zak on Tuesday November 21, 2023 @08:44AM (#38363490)

Thinkpads, for a long time have had a fan speed that's possible, but never reached by the firmware's automatic mode. On Linux, this sets the fan to its true maximum:

    # echo disengaged > /proc/acpi/ibm/fan

I use the thinkfan utility to run the fan more aggressively, including 'disengaged' over 70C.

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Re:Charging a lithium battery to 80% only? by nottorp on Tuesday November 21, 2023 @09:15AM (#38363877)

How's your hearing? If any left.

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Re:Charging a lithium battery to 80% only? by Zak on Tuesday November 21, 2023 @09:29AM (#38364056)

I put in foam-tipped earbuds if I'm doing a big compile or something, but the Ryzen 6850u runs pretty cool most of the time.

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Re:Charging a lithium battery to 80% only? by venj on Tuesday November 21, 2023 @10:04AM (#38364554)

Indeed, and for the t480s we could undervolt the CPU to help with thermals but these are not normally accessible to the end user.

So if you are an average user of a Lenovo laptop without technical skills, you probably have a machine that does not meet the advertised performance, and no way to fix it.

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Re:Charging a lithium battery to 80% only? by Perz1val on Tuesday November 21, 2023 @10:33AM (#38364990)

This is likely the case with all but gaming laptops. Most users won't care about performance under consistent, heavy workload, as much as it loading that .docx in 2 instead of 6 seconds. That burst of performance is what makes the system feel snappy and fast. If the user is happy, it was well worth the money too.

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