Jun 3, 2026 3:52:35 AM Jan Stary <[email protected]>:
On my Dynabook Portege X40-J running OpenBSD 7.9, the battery report
from `apm -v` always returns 0% despite the battery being fully
charged and AC connected.
AC/BAT state does change when AC is connected/disconnected, only the
battery remains at 0%.
apm -v output
(AC UNPLUGGED)
Battery state: charging, 0% remaining, 0 minutes recharge time
estimate
AC adapter state: connected
Performance adjustment mode: manual (2901 MHz)
(AC PLUGGED)
Battery state: CRITICAL, 0% remaining, 0 minutes life estimate
AC adapter state: not connected
Performance adjustment mode: auto (400 MHz)
There's nothing wrong with the battery physically, it reports
correctly under Linux and holds charge well.
So what does it report under Linux?
(And other OSes, for that matter?)
Attached is dmesg and sysctl output
sysctl hw would probably be enough for this :-)
acpibat0 at acpi0: BAT1 model "G71C000MA210" serial 4266600 type LiON
oem "BYD"
hw.sensors.acpibat0.volt0=4266.60 VDC (voltage)
hw.sensors.acpibat0.volt1=4266.60 VDC (current voltage)
hw.sensors.acpibat0.power0=1804.16 W (rate)
Batteries differ in the semantics of what they report
- surely it's not 4 kV and 1.8kW; probably mili.
hw.sensors.acpibat0.watthour0=1804.16 Wh (last full capacity)
It seems odd that this is exactly the same number
as the rate above in (mili)watts.
hw.sensors.acpibat0.watthour1=3300.26 Wh (warning capacity)
hw.sensors.acpibat0.watthour2=0.00 Wh (low capacity)
hw.sensors.acpibat0.watthour3=3308.11 Wh (remaining capacity), WARNING
hw.sensors.acpibat0.watthour4=1804.16 Wh (design capacity)
So 3308 Wh of the designed 1804 Wh remain?
I suspect the battery itself reporting something strange
- possibly linux's acpibat knows its quirks?
Jan
Thanks for your time, below is the information pulled from Void Linux and
FreeBSD (Live USB) while AC is unplugged.
Void Linux: upower (3rd party program), print contents of files under
/sys/class/power_supply/BAT1
FreeBSD: acpiconf, sysctl
--------------------------
Void Linux (Kernel 7.0.11)
--------------------------
$ upower dump
Device: /org/freedesktop/UPower/devices/battery_BAT1
native-path: BAT1
vendor: BYD
model: G71C000MA210
serial: 263
power supply: yes
updated: Wed Jun 3 04:57:13 2026 (0 seconds ago)
has history: yes
has statistics: yes
battery
present: yes
rechargeable: yes
state: discharging
warning-level: none
energy: 22.576 Wh
energy-empty: 0 Wh
energy-full: 27.612 Wh
energy-full-design: 53.13 Wh
energy-rate: 6.175 W
voltage: 15.4 V
charge-cycles: N/A
time to empty: 3.7 hours
percentage: 82%
capacity: 51.9706%
technology: lithium-ion
icon-name: 'battery-full-symbolic'
History (rate):
1780477033 6.175 unknown
1780477032 5.990 discharging
1780477030 5.467 discharging
1780477029 5.128 discharging
1780477027 6.160 discharging
1780477025 6.190 discharging
1780477024 5.436 discharging
1780477022 6.391 discharging
1780476965 5.846 discharging
----trimmed
$ find /sys/class/power_supply/BAT1/ -type f | xargs grep .
/sys/class/power_supply/BAT1/uevent:DEVTYPE=power_supply
/sys/class/power_supply/BAT1/uevent:POWER_SUPPLY_NAME=BAT1
/sys/class/power_supply/BAT1/uevent:POWER_SUPPLY_TYPE=Battery
/sys/class/power_supply/BAT1/uevent:POWER_SUPPLY_STATUS=Discharging
/sys/class/power_supply/BAT1/uevent:POWER_SUPPLY_PRESENT=1
/sys/class/power_supply/BAT1/uevent:POWER_SUPPLY_TECHNOLOGY=Li-ion
/sys/class/power_supply/BAT1/uevent:POWER_SUPPLY_CYCLE_COUNT=0
/sys/class/power_supply/BAT1/uevent:POWER_SUPPLY_VOLTAGE_MIN_DESIGN=15400000
/sys/class/power_supply/BAT1/uevent:POWER_SUPPLY_VOLTAGE_NOW=15400000
/sys/class/power_supply/BAT1/uevent:POWER_SUPPLY_POWER_NOW=12859000
/sys/class/power_supply/BAT1/uevent:POWER_SUPPLY_ENERGY_FULL_DESIGN=53130000
/sys/class/power_supply/BAT1/uevent:POWER_SUPPLY_ENERGY_FULL=27612000
/sys/class/power_supply/BAT1/uevent:POWER_SUPPLY_ENERGY_NOW=20589000
/sys/class/power_supply/BAT1/uevent:POWER_SUPPLY_CAPACITY=75
/sys/class/power_supply/BAT1/uevent:POWER_SUPPLY_CAPACITY_LEVEL=Normal
/sys/class/power_supply/BAT1/uevent:POWER_SUPPLY_TYPE=Battery
/sys/class/power_supply/BAT1/uevent:POWER_SUPPLY_MODEL_NAME=G71C000MA210
/sys/class/power_supply/BAT1/uevent:POWER_SUPPLY_MANUFACTURER=BYD
/sys/class/power_supply/BAT1/uevent:POWER_SUPPLY_SERIAL_NUMBER=263
/sys/class/power_supply/BAT1/serial_number:263
/sys/class/power_supply/BAT1/technology:Li-ion
/sys/class/power_supply/BAT1/power_now:12859000
/sys/class/power_supply/BAT1/present:1
/sys/class/power_supply/BAT1/power/runtime_active_time:0
/sys/class/power_supply/BAT1/power/runtime_status:unsupported
/sys/class/power_supply/BAT1/power/runtime_suspended_time:0
/sys/class/power_supply/BAT1/power/control:auto
/sys/class/power_supply/BAT1/manufacturer:BYD
/sys/class/power_supply/BAT1/energy_now:20589000
/sys/class/power_supply/BAT1/type:Battery
/sys/class/power_supply/BAT1/capacity:75
/sys/class/power_supply/BAT1/cycle_count:0
/sys/class/power_supply/BAT1/voltage_now:15400000
/sys/class/power_supply/BAT1/status:Discharging
/sys/class/power_supply/BAT1/alarm:0
/sys/class/power_supply/BAT1/model_name:G71C000MA210
/sys/class/power_supply/BAT1/voltage_min_design:15400000
/sys/class/power_supply/BAT1/hwmon3/in0_input:15400
/sys/class/power_supply/BAT1/hwmon3/power/runtime_active_time:0
/sys/class/power_supply/BAT1/hwmon3/power/runtime_status:unsupported
/sys/class/power_supply/BAT1/hwmon3/power/runtime_suspended_time:0
/sys/class/power_supply/BAT1/hwmon3/power/control:auto
/sys/class/power_supply/BAT1/hwmon3/power1_input:12859000
/sys/class/power_supply/BAT1/hwmon3/name:BAT1
/sys/class/power_supply/BAT1/capacity_level:Normal
/sys/class/power_supply/BAT1/energy_full_design:53130000
/sys/class/power_supply/BAT1/charge_control_end_threshold:100
/sys/class/power_supply/BAT1/energy_full:27612000
--------------------
FreeBSD 15.0-RELEASE
--------------------
# acpiconf -i 0
Design capacity: 53130 mWh
Last full capacity: 27612 mWh
Technology: primary (non-rechargeable)
Design voltage: 15400 mV
Capacity (warn): 552 mWh
Capacity (low): 0 mWh
Low/warn granularity: 531 mWh
Warn/full granularity: 531 mWh
Model number: G71C000MA210
Serial number: 263
Type: LiON
OEM info: BYD
State: discharging
Remaining capacity: 65%
Remaining time: 1:37
Present rate: 11041 mW
Present voltage: 15400 mV
# sysctl -a | grep -i battery
battery0: <ACPI Control Method Battery> on acpi0
hw.acpi.battery.info_expire: 5
hw.acpi.battery.units: 1
hw.acpi.battery.state: 1
hw.acpi.battery.rate: 10256
hw.acpi.battery.time: 99
hw.acpi.battery.life: 61
dev.battery.0.%iommu:
dev.battery.0.%parent: acpi0
dev.battery.0.%pnpinfo: _HID=PNP0C0A _UID=1 _CID=none
dev.battery.0.%location: handle=\_SB_.BAT1
dev.battery.0.%driver: battery
dev.battery.0.%desc: ACPI Control Method Battery
dev.battery.0.%parent:
