Battery Discharging Whilst On AC Power

[Eddie Plum]

Hi all, newbie here, so please be gentle

Despite what you may think from the title, I'm posting this in the software section for good reason. I recently noticed that my laptop battery (Lenovo ThinkPad T530 with original battery) discharges when the laptop is plugged in to mains power. It will discharge quite rapidly (~8-12 hours) from 100% down to 10% and then much more slowly (1% every day or two) from there down. I'm not sure if it will ever actually get to 0%, but even once it's got to 8%, it's pretty useless if I want to unplug and go somewhere.

If I unplug the mains and plug back in, not much changes, but if I pull the battery out and slot it back in, it will charge back up to 100% (or thereabouts) and then start discharging again.

"Dodgy battery!" I hear you say. Fortunately, my work laptop is also a T530, so I swapped batteries. My work laptop runs Windows 7 and the battery charges up to 100% and then stays somewhere around there (Lenovo's power software letting it drain down to 96% or so before topping it off). Likewise, the battery from my work laptop has been in mine for a little under 24 hours and is currently showing 10% (was 96% ish when plugged in, I used it on battery for a couple of hours whilst watching Windows charge it up on the other machine, then swapped the AC back over to mine. Work laptop battery charged up to 100% in my laptop, then started the slow downward spiral).

"Dodgy charger!" you cry. Nope, I tried the above experiment with my charger in both mine and my work laptop, so I've discounted that one.

"Dodgy laptop socket/motherboard/charging circuit!" Again, I've discounted that by booting my laptop into Windows 8 and the battery charges and remains charged.

Is there anything else I can try? Does this happen to anyone else? Anyone reading this got a T530 or similar, and does it work okay for you? Is there any info I can provide to help you lovely lot to diagnose the problem? I'm guessing it must be a setting somewhere in the power management software either in Ubuntu or the KDE desktop (17.04, unmolested and up to date).

Thanks in advance,

Ed.

[oshunluvr]

Sounds like APIC is not letting the battery charge.

Any comments in dmesg or syslog about the charger or the battery?

Try booting with acpi=nolapic in the boot options.

[oshunluvr]

Also:
http://code.jasonbhill.com/linux/fau...ovo-batteries/

[Eddie Plum]

Thanks for the replies @oshunluvr. Nothing obvious in dmesg or syslog (only "I found a battery" and "power device added" type messages at boot and hotplug respectively).

I'll try disabling APIC (any potential fallout I need to be aware of from that?)

[oshunluvr]

I'll try disabling APIC (any potential fallout I need to be aware of from that?

Maybe, but you don't have to make it permanent until you've tested it. Just add it to the boot line by editing grub menu and adding it between "quite splash". Then it won't be there next time you boot. If it fixes the issue and doesn't cause other problems, edit /etc/default/grub and add it there to make it stick.

[Eddie Plum]

Sorry, never got back to you on this. Alas, NOAPIC makes NODIFFERENCE. In fact, it makes no difference to anything, as far as I can see, so it can stay in there!

[Eddie Plum]

Update: Although applying NOAPIC and rebooting made no difference, I've been away for a few days and left the machine powered off. When I booted it back up, the battery charged up from 8% to full and has stayed full for almost 24 hours now. I'm not sure why a full power down for an extended period would make any difference to a reboot, but the battery seems to be remaining charged now.

Note: The laptop had been plugged in the whole time it was powered off and did not charge the battery at all. It was only once I'd powered it back on after a few days that it started charging.

Very weird, but I'm going to assume the NOAPIC actually has fixed it, but only after a full power cycle (not just a reboot) unless anyone else has any ideas why it would suddenly start working?