My laptop, after a hard 6 years of use, is finally showing signs of electrical wear and tear through a myriad of strange issues, this being one of the least severe of them.
I've experienced recently (and consistently) the issue that my laptop will cut out within about a second of being unplugged from an outlet. The strange thing about my issue is that it isn't simply a dead battery refusing to hold charge, as it (a) does not complain in sleep mode; (b) will turn on, but at times will not show bios splash and at other times will get past grub and die upon OS initialization; (c) delays before dying when unplugged while powered by about the same time as it would delay before showing unplugged before the issue presented itself; and (d) relays accurate ACPI information that shows nothing wrong (as far as I can tell). If not for (a) and (d), I could have found it reasonable to consider it a bad connection either to the battery or on the motherboard, the former of which I attempted to test by reinserting the battery several times.
The data to back up (d) is:
$ cat /proc/acpi/battery/BAT1/state present: yes capacity state: ok charging state: charging present rate: 843 mA remaining capacity: 3546 mAh present voltage: 12514 mV $ cat /proc/acpi/battery/BAT1/info present: yes design capacity: 4400 mAh last full capacity: 3782 mAh battery technology: rechargeable design voltage: 11100 mV design capacity warning: 0 mAh design capacity low: 0 mAh cycle count: 0 capacity granularity 1: 1 mAh capacity granularity 2: 1 mAh model number: MS-1058 serial number: battery type: LION OEM info: MSI Corp. $ acpi -V Battery 0: Full, 100% Battery 0: design capacity 4400 mAh, last full capacity 3782 mAh = 85% [...]
As far as I can tell, there is nothing wrong with the battery itself. I bought it less than a year ago from Amazon to replace the previous battery that had very obviously lost the ability to hold charge.
If the laptop is unplugged while sleeping (with the sleep indicator blinking), it will drain power from the battery as it normally would while on if this issue was not present and has no issues with being unplugged, leading me to believe that it may be a kernel or other software issue (though I don't recall making any noteworthy changes in the past few days). Once returned to AC after draining power in sleep, it will recharge the battery as normal.
EDIT: Not sure if this information is entirely useful, but the laptop is an MSI A6000 running Linux Mint 12.