MobileRead Forums - View Single Post - PRS-650 battery drain

delphin · 05-25-2011, 03:22 AM

Lot's of other users have had experience with rapid battery discharge on the 650, but it can usually be fixed by a full reset, so it's good that you tried that before jumping to the conclusion that the battery has suddenly gone bad.

This has happen to me, but only once so far. Like you, I had recently charged my PRS-650, and came back to find it completely discharged.

I suspect that what is happening is that due to a minor bug of some kind, a erroneous zombie process is getting spawned and running with a high CPU load in the PRS-650's internal Linux OS. When this happens, apperently this bad sub-process doesn't 'sleep' properly or shut down, so in just a few hours it completely drains the battery.

I know for a fact that the PRS-650 is a bit twitchy about stray user inputs; for example, it's rare, but you can completely lock-up the PRS-650 sometimes by simply double tapping to open a book (instead of using a single tap as is correct).

This makes me wonder if the situation that causes this 'rapid battery discharge' situation might also involve stay inputs that arrive just at the wrong moment (which may be what spawns the zombie 'battery sucker' process).

So now I am careful to always single click, when single clicks are needed, and I also avoid accidentally hitting any other keys (or the touch screen) when sliding the power switch and shutting down (on the theory that such inputs, just as the reader is trying to shut down, could hang a process, and create a zombie battery sucker process).

Maybe this theory is totally wrong, and it's just good luck, but since taking these measures, it's been a couple months now, and I have has ZERO problems with sudden battery discharges.

Edit: Another potential battery draining situation could occur if there is excessive dust on, or around the edges of the touch screen. This can trigger stray touch inputs, and increase the CPU load, as it has to wake up every few milliseconds to try to figure out what is gong on.

Normally, when the touch screen gets a stray input that can't be processed properly, a little circle with a bar, like a wrong way sign, shows up on the status bar at the bottom right. Not sure if this is always the case, so if there is gunk around the edges of your screen, and your battery life is short, it might be a good idea to clean around the screen.

05-25-2011, 03:22 AM	#4
delphin Evangelist Posts: 434 Karma: 346901 Join Date: Dec 2010 Device: SONY PRS-650	Lot's of other users have had experience with rapid battery discharge on the 650, but it can usually be fixed by a full reset, so it's good that you tried that before jumping to the conclusion that the battery has suddenly gone bad. This has happen to me, but only once so far. Like you, I had recently charged my PRS-650, and came back to find it completely discharged. I suspect that what is happening is that due to a minor bug of some kind, a erroneous zombie process is getting spawned and running with a high CPU load in the PRS-650's internal Linux OS. When this happens, apperently this bad sub-process doesn't 'sleep' properly or shut down, so in just a few hours it completely drains the battery. I know for a fact that the PRS-650 is a bit twitchy about stray user inputs; for example, it's rare, but you can completely lock-up the PRS-650 sometimes by simply double tapping to open a book (instead of using a single tap as is correct). This makes me wonder if the situation that causes this 'rapid battery discharge' situation might also involve stay inputs that arrive just at the wrong moment (which may be what spawns the zombie 'battery sucker' process). So now I am careful to always single click, when single clicks are needed, and I also avoid accidentally hitting any other keys (or the touch screen) when sliding the power switch and shutting down (on the theory that such inputs, just as the reader is trying to shut down, could hang a process, and create a zombie battery sucker process). Maybe this theory is totally wrong, and it's just good luck, but since taking these measures, it's been a couple months now, and I have has ZERO problems with sudden battery discharges. Edit: Another potential battery draining situation could occur if there is excessive dust on, or around the edges of the touch screen. This can trigger stray touch inputs, and increase the CPU load, as it has to wake up every few milliseconds to try to figure out what is gong on. Normally, when the touch screen gets a stray input that can't be processed properly, a little circle with a bar, like a wrong way sign, shows up on the status bar at the bottom right. Not sure if this is always the case, so if there is gunk around the edges of your screen, and your battery life is short, it might be a good idea to clean around the screen. Last edited by delphin; 05-25-2011 at 03:39 AM.