T420 hibernating due to battery level?

Every couple days my T420 will just randomly hibernate.. I'm using it, then the screen just suddenly dims out, the hard disk usage goes crazy for like 30+ seconds, the power light starts flashing, then it shuts off. I hit the power button, and it boots right back up from hibernate. This time I read the windows boot message, and it said "click to continue resume" and it said it shut down to critical battery level.

I'm at 94% battery with my charger plugged in..

This started happening every week or so maybe 2 months ago, lately it has started doing it every 1-3 days or so. I'm not sure if it always happens when on the charger or not, I haven't payed attention to that.

I have the 94wh extended battery, it shows 13% wear level. I have changed the processor out with a core i7 2670QM, added a 8gB stick of memory to go with the 4gB stick, and I have a second hard drive in the cd rom bay. I'm running 1.37 bios (so my memory can run at 1600mhz), and I'm on windows 7 ultimate. It has the factory battery, and a 90w ebay charger.

Anyone know if this could be a software problem? Bios problem? Possibly a battery, or the fact its an aftermarket charger?

 

mmm, Looks like TP fan control might be my problem
Critical battery shut down - at 50%!!!! (T420) - Lenovo Community

Anyone else have any input on this? I really like running TP fan control with my core i7, helps keep my temps at bay. I like having the fan ramp up to 3k rpm at 40c, keeps my notebook running a good 42-50c while surfing the web and general use. Not to mention, the stock bios settings, wouldn't even allow my fan to hit 4500rpm until 90c+, and I'd quickly hit 98c or so and get throttled. Not I have it ramp up to 4500 at 80c, and at 90c ramp up beyond stock limits to 5400, I rarely break 90c now even running prime 95 for 20+ minutes.
Btw my fan is very quiet in this laptop, almost inaudible at 3000rpm, and at 4500 not all that loud. Contradictory to what I've read about many T420's and having a loud fan, and people actually setting the fan to not run as high with TP fan control, instead of making it run faster like I am!


edit: After more googling, it appears that TPfan control could be my problem. From other people having issues on varying models of thinkpads, TP fan control doesn't seem to get along with Lenovo power manager.

Anyone know of a work around? I might even just disable hibernate, In 9 months I have never let the battery drop low enough to hibernate, I always plug it in at 7% when it warns me or I could manually hibernate if I'm away from a charger... I love having my laptop not run toasty hot all the time, keeping manual fan control is high on my list of wants!

re-edit: Ok so it happened again, without it being plugged in, this is the first time its happened twice in one day.
I went ahead and disabled auto-hibernate, I'll see what happens over the next few days.

 

I don't have a T420 here, but most of my ThinkPads run Power Manager along with TPFC and I've never bumped into this issue.

Let me make myself clear: I'm not saying that the issue does not exist or that you're imagining things. Just that I've never ran into it although I've seen my unfair share of ThinkPads.

It might be a mismatch between a particular version of PM vs. a particular version of TPFC.

You're doing the smart thing by disabling hibernation IMO.

Good luck.