Rapidly draining battery


Nov 9, 2013
Somehow, my laptop went from 92% power to fully drained (as in, it shut off on its own) in just 52 minutes. Despite the fact that all I had open were Notepad, Chrome (admittedly with around nine or ten tabs open, but I don't know if those would account for the rapid drain), and Acrobat Reader (two very long documents; again, could that cause drain, even when minimized?). The battery is, admittedly, five years old (system: Toshiba Satellite C855-S5350), and when I set up a battery report, it turns out that its full charge capacity has declined from 47,520 mWh to 38,383 mWh. Which should still manage two hours (I think the original capacity was earmarked for three hours, at least). I had the machine cleansed of malware back in November.


Jun 6, 2006

Yeah, 5 yr old battery that only lasts an hour? That sounds about right for a laptop. My last laptop would only last about 30 minutes without being connected to a power source. Originally it would like for 4 hours. Batteries fade.
SSD's can help.
CPU downgrades can help (but who wants to go slower?)


Well....5 years is a long time. I've had them go before 5 years quite often.
Also....I just googled it and I have seen 2-4 years.....3-5 years.....1000 charge cycles.....so you are in the "need a new battery" region at least.


Dec 6, 2008
I've had four laptops in 12 years. Here's the rundown of how they have faired for me:

2006 model Dell E1705 - 2 years before not holding charge
2009 model Dell Inspiron ? - 3 years before not holding charge
2011 model Lenovo Thinkpad T410 - still holding charge (it is a larger optional battery, not the standard one)
2014 model HP Pavillion G7 - still holding charge

The latter two are still in operation but I rarely ran any of these straight off batteries and only did so to cycle charges. I kept/keep them mostly plugged into the AC adapter as they were/are used for many hours daily. Recommendations for doing this variate between manufacturers.
To understand what's happening, computers gauge battery level by the voltage. As the battery loses charge, the voltage slowly drops. An algorithm on the computer translates the current voltage into a % charge remaining. (It's a bit more complicated than this, but this is basically what happens.)

As the battery gets older, the maximum amount of current its able to deliver decreases. So whereas before the battery might be able to put out 30 Watts, now it might only be able to put out 20 Watts. On top of this, the maximum current is linked to the voltage - lower voltage is coupled with lower current. So at 100% charge your battery might be able to put out 20 Watts. At 80% it may drop to 10 Watts, which might not be enough to keep your laptop powered on.

If the battery reaches this state, one of two things can happen. Either the laptop immediately powers off because it's not getting enough power, and you have a battery which still has most of its charge but dies at 80%. Or the laptop's charging circuitry recognizes this situation and sets the new 0% at the old 80%. So your battery's max capacity shows up as severely depleted.

In either case, the only fix is a new battery. In theory it's possible to recondition Li-ion batteries, but it's highly not recommended because they have a tendency to catch on fire or blow up if you do it just slightly wrong. For future reference, to try to prolong the lifespan of your battery and stave off diminished capacity:

  • ■ Avoid charging the battery to 100%. Many laptops now come with an app or setting which lets you limit the max charge to something like 80% or 90%. Use it if you have it. Others do this automatically (a hardware info app will report the battery's mAh capacity as less than its true capacity).
    ■ Avoid discharging the battery to 0%. This one is pretty easy - don't run the laptop on battery until it dies. Plug it back in before the battery state gets too low. The microscopic components of the battery physically change shape as they charge and discharge, and charging or discharging to the extremes can cause physical damage which leads to reduced capacity.
    ■ Contrary to the above two points, you should charge it to 100% and discharge it entirely about once every month or two. This helps the charging circuitry recalibrate and adjust the charging cycle to accommodate the gradual degradation of the battery with use. Between these monthly full cycles, try keeping the battery state between 20%-80% charge.
    ■ Avoid getting the battery very hot. This can be difficult to impossible on gaming laptops. But for most regular laptops, it means making sure there's always adequate ventilation underneath the laptop, and not doing things like using it on top of a blanket.
    ■ Avoid leaving the laptop plugged in all the time. If you do use it primarily plugged in, take it off of AC about once a week and exercise the battery a little (run it down to 20%-30% and charge it back up to 80%).
This used to be a lot easier when laptop batteries were removable. You could just take the battery out (charged to about 70%), and put it back only when you needed to take the laptop off AC. But now that most batteries are internal, you have to work to maintain them.
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