I have a rather odd issue that I’m curious to know if anyone else has with their AMD 13-inch laptops. I have two 7840U boards and a 7640U board that I’ve been using the last year or so, mostly plugged in, and I noticed that one of them have a rather high cycle count given that it’s always plugged in. Upon further investigation, what appears to be happening is it will charge up to 80% (the limit I set in BIOS) and once it stops charging it will run off of the USB input power for a bit, but within a few minutes will start drawing power from the battery and reduce the power being puled from the charger. Then, it will drain to 75% at which point it will start charging again, up to 80%.
A bit of additional information on some things:
- I verified that the input power drops when the battery is draining with one of those USB power monitors; it won’t drop to zero but to around 3-4 watts with the battery picking up the rest. This happens even if I leave the laptop idle.
- I normally use a Dell Thunderbolt 4 dock (WD22TB4) but also happens with any other charger I’ve tried, including a 140W Ugreen charger.
- This behavior is NOT observed on the other 7840U nor the 7640U laptop with exactly the same bios and operating system configurations. They will charge to 80% and stay there, not drawing power from the battery at all.
- All of the laptops are on the same bios and EC version (3.17)
- Battery power/usage readings are from upower.
I don’t plan on doing any other testing at the moment as I’ll be swapping out both the mainboard and battery in a week or so and I regularly use this machine, so I’ll test it externally once it’s been swapped out. At the moment I’m just wondering if anyone else has experienced this issue.
Lastly, I don’t believe this is relevant as I don’t believe the battery charging can be controlled directly by the OS (and therefore didn’t tag this with Linux), however everything is running up-to-date Arch Linux installs currently with kernel version 6.18.2-arch2-1, though this has been happening for a while.
Edit: Here’s the output from upower showing the battery draining while in pending-charge status:
% upower -i /org/freedesktop/UPower/devices/battery_BAT1
native-path: BAT1
vendor: NVT
model: FRANGWA
serial: XXXX
power supply: yes
updated: Wed 24 Dec 2025 12:25:45 PM MST (6 seconds ago)
has history: yes
has statistics: yes
battery
present: yes
rechargeable: yes
state: pending-charge
warning-level: none
energy: 44.5824 Wh
energy-empty: 0 Wh
energy-full: 58.1119 Wh
energy-full-design: 60.6042 Wh
voltage-min-design: 15.48 V
capacity-level: Normal
energy-rate: 7.83288 W
voltage: 16.346 V
charge-cycles: 150
time to empty: 5.7 hours
percentage: 77%
capacity: 95.8876%
technology: lithium-ion
icon-name: 'battery-full-charging-symbolic'
History (rate):
1766604345 7.833 pending-charge
1766604315 7.786 pending-charge
1766604285 7.353 pending-charge
1766604255 7.074 pending-charge