Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have completely followed this walkthrough, but my computer is still shutting down at 3%. The advanced setting for critical battery level refuses to allow me to set this under 3%. My laptop battery is getting a memory and is losing 1% total every recharge. My BIOS does not have any settings for this/is not configurable.

Any solutions?


I decided to test how bad it is to fully discharge a Lion battery that can "get no memory" on a previous laptop I was using last year that would only charge to 5% and had a runtime of about 10 minutes.

The laptop has been unplugged for over a month, and I just started recharging it yesterday. To my surprise after about 30 minutes it already had a 15% charge on it. I just checked back on the progress after it was going up and up, and it is now 100%! (So if a full discharge damages it, this is an odd case, since I now have a battery that is like new!)

That system was running XP and had the same issue where it would automatically shutdown at 3% so I could not fully discharge it. Until I let it naturally drain that last 3% by leaving it unplugged, did it finally get to ZERO. I am now starting to wonder if the guides and advice out there are actually correct, because that was a Lion battery and I can tell you, it indeed had a memory.

Has anyone actually fried a Lion battery by fully discharging it to 0%?

Most likely I am going to try the same thing with my current laptop, because I have lost another 6% (in memory) since I started this, believe it or not.

share|improve this question
Are the batteries particularly hot and/or being overcharged? L-ion batteries can rapidly loose capacity if they are kepy fully charged while hot. IIRC a L-ion battery that is kept full at 40°C permanently loses something like a third of it's capacity in a year. Also, are you using the correct power pack (or alternatively the "wrong" battery for the laptop)? This might be charging the battery too quickly, which may also cause a loss of capacity. – DMA57361 Sep 30 '10 at 10:40
@DMA I have been especially careful not to overcharge it. Honestly I have no way of gauging the actual temperature, but I have my monitor brightness set to lowest and the CPU idles at 4% usage most of the time. The battery and power supply is what came with the laptop and was supplied by the manufacturer. – Talvi Watia Sep 30 '10 at 10:58
Fair enough, gets a few of the basics out of the way. As for temperature, just feel it - does it feel hot? – DMA57361 Sep 30 '10 at 11:06
@DMA not really. It has on occasion, but not for very long. (the rare instance my CPU has to churn for 30 minutes.) – Talvi Watia Sep 30 '10 at 11:20
Well, in that case I'm out of helpful comments. I will say that I agree with Moab thou, L-ion batteries don't suffer from a real memory effect - they just lose capacity. For the real memory effect you need to partly discharge a NiCd battery to the same level (eg, 30%) then recharge to full repeatedly. What then happens is the battery will still charge to full, but when discharging will experiance an unexpected drop in voltage once it get's below the "memory point", in this example below 30%. – DMA57361 Sep 30 '10 at 11:37
up vote 1 down vote accepted

Lion batteries do not have "memory" like NiCad and NmH do. Draining a Lion battery to 0 can damage it.

They do deteriorate and need occasional calibration. Consult your owners manual for your laptop on how to do this.

share|improve this answer
Ok. So I guess I need to know how to re-calibrate the fuel gauge then. Obviously, I've done a full discharge (down to 3%) and it did not correct. – Talvi Watia Sep 30 '10 at 2:27
I can be different for various manufacturers, consult your owners manual. – Moab Sep 30 '10 at 22:55

Is it possible you can run on AC power until you actually need to use your battery? I run my notebook on AC power ONLY (no battery installed) when I'm at home or don't need to bring it with me, and plug my fully charged battery in and run it till its completely dry of battery juice.

share|improve this answer
This is not what I am asking. I am trying to FULLY drain my battery to 0% since it is gaining a memory. – Talvi Watia Sep 30 '10 at 1:52

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.