Lenovo Laptop Battery Reading Erratically

[xnecron101x]

I have a Lenovo Y40-80 that I purchased two years ago. About a year ago exactly, I had to replace the battery because it no longer charged. Fast forward to now, I have replaced the display on the laptop and only a week or so ago replaced to HDD with a Samsung Evo SSD and reinstalled both Windows 8.1 and Ubuntu 16.04.3 from scratch.

The battery seemed to work well for the first couple of days (and even lasted much longer than before), but over the last couple days, the battery percentage has been reading as 100% for the first 2-3 hours, then very quickly draining down to about 25-30% within the next 2 hours, then running out of power completely. So clearly the battery life itself is not much of an issue, but the incorrect reading is more than a little inconvenient.

What I have done:
-Installed the necessary drivers from Lenovo's website (did this the first day)
-attempted to recalibrate the battery by charging it completely and then letting it drain to 0 and recharging again without letting it fall asleep

Also, the issue is persistent in both Windows and Ubuntu which makes me think it's either a firmware issue or an issue with the battery itself, but like I said before, the battery life is actually quite good compared to what I had before, but I'd really like to get this readout to be more accurate.

Any ideas, troubleshooting steps etc. are greatly appreciated!

Edit: While trying to troubleshoot something else, I disabled Fast Boot in Windows, rebooted into Ubuntu, and the battery meter now seems to be discharging normally. I don't want to rush to conclusions, but I'm taking this as a positive sign. I'll try booting into Windows after a while to see if it's reading correctly now too.

Edit 2: it looks like that optimism was ill-fated, we're back to reading incorrectly again and I'm pretty much out of ideas

 

[webworkings]

Sounds like you need a new battery to me.

 

[xnecron101x]

Sounds like you need a new battery to me.

Well two things: first of all, Does that not seem odd then? that the battery would last a long time, just read incorrectly?

Secondly, I've discovered something else a little screwy that may be related, but I honestly don't know as I've never come across this sort of situation before. Because my laptop has also recently had a lot of trouble keeping track of the time (which I actually started noticing more and more after making the initial post) in both Windows and Ubuntu, I'm starting to think that somehow, in some way, and for some reason, the CMOS battery on the motherboard is acting up. I haven't gotten around to opening the computer yet as I've been busy, but it does seem to me that a computer that's confused about what time it is will definitely be confused about how long its own battery lasts. The only thing I can't figure out is what exactly is happening with the time. I would assume that an issue with the CMOS battery would reset the time and date to the minimum allowed by the motherboard, but the clock actually just jumps ahead a few hours.

It's really starting to seem like I just need a new laptop as this one has been driving me up a wall, but that's just not in the cards right now monetarily, so again, any input/help/ideas greatly appreciated. I haven't given up quite yet.

 

[webworkings]

You may want to try replacing the CMOS battery first. If there is an error in the charging related to that in any way (not a likely cause, but one never knows) then that would be a lot cheaper to replace.

 

[xnecron101x]

You may want to try replacing the CMOS battery first. If there is an error in the charging related to that in any way (not a likely cause, but one never knows) then that would be a lot cheaper to replace.

Yeah, I think I'm gonna do that first, and if it still doesn't work, I'll just replace the battery. Thanks for the help