Problem: I have a laptop. It works very well on AC power, but on battery power, it powers off in a few minutes, if not seconds, without warning.
In many of such links, people suspect 'a fan problem,' but I doubt it, because it never happens on AC power. On AC power, I run very heavy programs that use all of 4 cpus with hyperthreading, (so CPU usage 800%) without power off even a single time.
To describe my system a little bit more,
- it is ASUS N55SF (15", i7 quad core, 8GB, and I added SSD).
- I use Ubuntu 12.04, and I strongly suspect this might be a problem, but no evidence yet.
- Once, I have used a Targus charger (19V 4A) for a few weeks instead of the original charger (19V 6A), and from this time the batter calibration got mangled, but not sure if it is related.
- I fully charge, and the battery history graph indicates 100% charge, and it shuts down a few seconds later on battery. When reconnected to power and powered on, battery meter indicates 100% again. Measured with multi-meter, it IS full.
- The charger output voltage is 19V, but the voltage in software battery meter is 11V. Could this be a problem?
As N55SF doesn't have a battery calibration, I did manual full charge and discharge some times, but no help.
I got a new (supposedly unused unless the seller is lying) battery from ebay, and I still have same problem (even worse). I got the battery from ebay because ASUS doesn't have its official store, as far as I know.
With all pieces of information gathered, I tried to rebuild the scenario like this:
- it powers off without warning --> sensor does not recognize the batter voltage lowering?
- Maybe battery output voltage fluctuates, and maybe a protection circuit against it is broken?
but still no clue.
For now, I got another cheap laptop ($200) for mobile use, and gave upon using the main laptop on the go. However it will be great if I could fix this problem.