Single episode of quickly cycling through "Charging" & "On battery" messages.
A couple of days ago my laptop (Toshiba Satellite) went through an episode where it would cycle as follows
- Running-on-external-power (and charging battery) behaviour for ~3 seconds.
- Notifications area on taskbar (or "system tray") shows icon for (mostly full) battery & power cable, indicating external power is being supplied.
- Hovering over icon in notifications area shows a tooltip message like "Charging (85%)".
- Screen is slightly brighter.
- Running-on-battery behaviour for ~1 second.
- Notifications area on taskbar (or "system tray") shows icon for (mostly full) battery, indicating no external power is being supplied.
- Hovering over icon in notifications area shows a tooltip message like "Battery (85%)".
- Screen is slightly dimmer.
and then repeat. Until I turned it off. (Sorry, I didn't get the exact wording of the tooltip messages.)
This happened after the laptop had been on for less than a day, and I had purposely rebooted after doing a couple of updates, and not launched a bunch of applications, but rather manually shut down a bunch of (what I deemed) non-essential applications and services running in the background (think update agents, VPN agents, etc.). Then I ran a backup script from a relatively simply batch script that I wrote, which calls 7-Zip. I have run it before, with no such issues. I started the script on this occasion, and there were initially no issues. I went out; when I came back, the script was still running, and the symptoms had appeared.
It never did that before, I don't think. Usually I have the laptop always plugged in to the power, whether the laptop's on or off. Commonly I put the laptop to sleep; occasionally I turn it fully off.
Since the above episode — to my surprise, but thank goodness — it's not doing it anymore.
So what could cause this???
Hardware issue on power adapter? But why would it be a one-off? It shouldn't really be overheating more than usual in this cool weather. I don't think the cables were moved to be suddenly bent or anything. Likewise the connector: I did give it a bit of twist during the episode to see if I could improve the connection, and also tried to push the power cable into the power brick (it was already fully in) but there was no effect from either.
Power fluctuations at the wall socket?? I didn't notice any other appliances (mainly the room lights/lamp) misbehaving.
Fault in the laptop's power supply unit? No prior evidence of such.
Fault in the laptop's battery? The laptop battery is definitely old and in decline. But the system was not showing symptoms of the battery going missing, but rather symptoms of the external power supply dropping out. The battery is generally reported to be 100% charged, unless the power has been disconnected.
Fault in the software (Windows OS, or some power-management component)?
^(NOTE: I am forced to choose a "flair" for this post. I am not allowed to choose a flair that says "I don't know whether it's a hardware or software issue" :-/)
Is there any test I should do?
- Could I learn anything useful by hooking the output of the power adapter up to a multimeter? Or an oscilloscope? Any safety risk? Any risk of damage to the meter/scope/adapter?
Any further action I should take?