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My laptop is an Acer Aspire 5750 that used to run Windows 7 but is now dual-booted with Ubuntu 12.04 (now my predominant OS). Recently an annoying bug developed in that my laptop won't boot without being connected to the charger.

Once booted I can unplug the charger and use as normal, which gives me around 2 hours of battery life. I don't know what is causing this and would like any advice.

For the record this is the contents of /sys/class/power_supply/BAT0:

==> /sys/class/power_supply/BAT0/alarm <==
0
==> /sys/class/power_supply/BAT0/capacity <==
76
==> /sys/class/power_supply/BAT0/charge_full <==
1995000
==> /sys/class/power_supply/BAT0/charge_full_design <==
4400000
==> /sys/class/power_supply/BAT0/charge_now <==
1517000
==> /sys/class/power_supply/BAT0/current_now <==
741000
==> /sys/class/power_supply/BAT0/cycle_count <==
0
==> /sys/class/power_supply/BAT0/device <==

==> /sys/class/power_supply/BAT0/manufacturer <==
PANASONIC 
==> /sys/class/power_supply/BAT0/model_name <==
Li_Ion_4000mA 
==> /sys/class/power_supply/BAT0/power <==

==> /sys/class/power_supply/BAT0/present <==
1
==> /sys/class/power_supply/BAT0/serial_number <==
0008
==> /sys/class/power_supply/BAT0/status <==
Discharging
==> /sys/class/power_supply/BAT0/subsystem <==

==> /sys/class/power_supply/BAT0/technology <==
Li-ion
==> /sys/class/power_supply/BAT0/type <==
Battery

==> /sys/class/power_supply/BAT0/uevent <==
POWER_SUPPLY_VOLTAGE_MIN_DESIGN=10800000
POWER_SUPPLY_VOLTAGE_NOW=11422000
POWER_SUPPLY_CURRENT_NOW=741000
POWER_SUPPLY_CHARGE_FULL_DESIGN=4400000
POWER_SUPPLY_CHARGE_FULL=1995000
POWER_SUPPLY_CHARGE_NOW=1517000
POWER_SUPPLY_CAPACITY=76
POWER_SUPPLY_MODEL_NAME=Li_Ion_4000mA 
POWER_SUPPLY_MANUFACTURER=PANASONIC 
POWER_SUPPLY_SERIAL_NUMBER=0008

==> /sys/class/power_supply/BAT0/voltage_min_design <==
10800000   
==> /sys/class/power_supply/BAT0/voltage_now <==
11422000

Updated information: - Without power the laptop won't even reach the acer logo or grub screen. It is simply completely unresponsive to the power button. - I have also found that if I put the laptop into sleep mode when it boots back up it has been completely restarted, it doesn't save the current session as it should despite having full battery when turned off (it also didn't drain any battery at all during 'sleep')

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1  
I would try a new battery. 2 hour lifespan is abysmal. –  Ramhound Mar 6 at 21:52
    
To be honest I mostly use it plugged in (which I know will have damaged the battery life) or in one lecture at a time. I may yet replace the battery but even of I do I'd like to know (mostly for future reference and curiosity) what is causing this problem. –  user163911 Mar 7 at 0:39
2  
I suspect the problem is the battery itself hence my suggestion to fix it –  Ramhound Mar 7 at 0:51
    
Batteries used to have a limited life (a year or so). Things are better now, but they still have the annoying habit of dying before the machine does... –  vonbrand Mar 7 at 2:02
    
What happens if you boot Windows? Or does the system just not power on at all? –  Canadian Luke Mar 7 at 6:10

1 Answer 1

Hard drives can use more power when first spinning up than they do at speed... Many raid enclosures will spin up hard drives in sequence to avoid power spikes. It is possible that your battery has enough juice to run, but not boot up.

Related topic here: http://www.tomshardware.com/forum/262119-32-hard-drives-window

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Even if it's not the hard drive, the hardware runs probably through some checks to see what's there - which of course needs more power(or, what my guess is - voltage) than the fully booted OS which can power down most of the hardware(CPU, display, etc.) –  MKzero May 23 at 10:47

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