Battery

So today i was in class and used my battery till it only has 5% left so it went to hibernate mode. When i turned it on and checked battery wear, it says its 3%. i have only had this laptop since monday, should i be worried?

 

short answer: no.

long answer: i've let my machine discharge <5% four times since getting my machine in may, two of which were attempts at calibrating the battery. during both calibrations i let the battery drain very close to <1%. power settings didn't start hibernation, the critical action, till 1% remaining with the system beeps/alarms going off. some people think that's purposefully and needlessly deteriorating battery life and others consider it a proper calibration, to be performed every few months if the battery's otherwise on constant power.

anyway, after the first calibration the wear level rose to 3.5% (from technically a "negative wear level" meaning the current capacity was reading higher than the total capacity for the first couple months). it sort of freaked me out so i made a post about it and the consensus was mixed, like i said. and then i started to think that if i calibrated every few months (i.e. four times/year) with the same result increasing the wear level by ~5% each time, that's roughly 20% wear per year. battery would be at 50% wear 2.5 years out. so i concluded that that was pretty normal and nothing to worry about.

with my last calibration, the wear level didn't change at all so 50% wear is even further out than i originally estimated (as it probably should be). but yea, the whole concept is to calibrate every so often in order for the battery to redetermine its total capacity. plus built-in safeguards prevent you from ever reaching a full charge or a total discharge anyway.

long story short, probably not the best idea to run the battery down to 5% everyday, but long-term it's probably moot. if you want to leave the machine on constant power that's fine too. the battery undergoes natural discharge so you're cycling even if it's always plugged in. if you're storing a battery long-term it should be at 30-40% capacity, otherwise just use your machine normally and you shouldn't have anything to worry about. that's why the battery's there after all.

and yes, i learned all of that from NBR. hope that's some peace of mind for you.


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EDIT:
damn, i just edited this reply at least twenty times. haha

 

Do you still have 3%wear after charging it back to 100%?

 

yeah the wear is still there after charging it back to 100%.
@mattcheau, thanks that makes me feel a lot better. The battery when it first came had a full charge capacity over the designed capacity, now its just below, so i guess thats normal?

 

yup, that's more precisely what i meant--the fully charged capacity exceeded the designed capacity. so we've both experienced nearly the same thing.