On Mon, 1 Dec 2025, Qingwei Zhang via linux wrote: > > Hi rday, > > Your understanding of the start/end thresholds is correct — the > battery should start charging at 75% and stop at 80%. If your Dell > laptop keeps charging past 80%, it usually means the firmware/EC > does not actually support Linux-controlled charge thresholds, even > though the sysfs files exist. > > On many Dell models, the kernel exposes charge_control_*_threshold, > but the hardware ignores them unless the feature is supported by the > Dell WMI battery driver or configured directly in BIOS. > > A few quick checks: > > lsmod | grep dell > modprobe dell-wmi-battery # if supported > > If dell-wmi-battery is missing (common), Linux cannot enforce > thresholds. In that case, charging limits must be set in the BIOS > (“Custom Charge”) if available — otherwise they cannot be > controlled. > > In short: the sysfs interface is present, but your firmware isn’t > honoring it. it appears that, no, that specific module is not on my system: /lib/modules$ find . -name dell-wmi* ./6.12.43+deb13-amd64/kernel/drivers/platform/x86/dell/dell-wmi-sysman ./6.12.43+deb13-amd64/kernel/drivers/platform/x86/dell/dell-wmi-sysman/dell-wmi-sysman.ko.xz ./6.12.43+deb13-amd64/kernel/drivers/platform/x86/dell/dell-wmi.ko.xz ./6.12.43+deb13-amd64/kernel/drivers/platform/x86/dell/dell-wmi-led.ko.xz ./6.12.43+deb13-amd64/kernel/drivers/platform/x86/dell/dell-wmi-ddv.ko.xz ./6.12.43+deb13-amd64/kernel/drivers/platform/x86/dell/dell-wmi-descriptor.ko.xz ./6.12.43+deb13-amd64/kernel/drivers/platform/x86/dell/dell-wmi-aio.ko.xz ./6.12.57+deb13-amd64/kernel/drivers/platform/x86/dell/dell-wmi-sysman ./6.12.57+deb13-amd64/kernel/drivers/platform/x86/dell/dell-wmi-sysman/dell-wmi-sysman.ko.xz ./6.12.57+deb13-amd64/kernel/drivers/platform/x86/dell/dell-wmi.ko.xz ./6.12.57+deb13-amd64/kernel/drivers/platform/x86/dell/dell-wmi-led.ko.xz ./6.12.57+deb13-amd64/kernel/drivers/platform/x86/dell/dell-wmi-ddv.ko.xz ./6.12.57+deb13-amd64/kernel/drivers/platform/x86/dell/dell-wmi-descriptor.ko.xz ./6.12.57+deb13-amd64/kernel/drivers/platform/x86/dell/dell-wmi-aio.ko.xz so that explains it, thanks. rday