PRS-650 New Owner - A few questions.

[elcreative]

Definitely not... full discharge starts to cause internal crystals to form which initially reduce capacity and eventually destroy the cell(s)... this is not anecdotal information, it's from the battery manufacturers... if you leave the unit unused then it's also recommended to turn it off fully with a half charge...

Originally Posted by Fortissimo

Also, when you first got your reader, did you caliberate the battery? That is, by allowing it to discharge fully before you charge it again? I read in a previous thread that this is bad for LiPo batteries in general. But perhaps I have to do this the first few times I charge it?

I'm really trying to get the best out of my reader.

[Fortissimo]

Originally Posted by elcreative

Definitely not... full discharge starts to cause internal crystals to form which initially reduce capacity and eventually destroy the cell(s)... this is not anecdotal information, it's from the battery manufacturers... if you leave the unit unused then it's also recommended to turn it off fully with a half charge...

Thanks El. As soon as it hits the halfway mark, it's getting a re-fill. Also, apparently, when the red light goes off is actually not the time to turn off the power? I should leave it plugged in for about 2 more hours. Is this correct, sir?

[elcreative]

You don't have to leave for another couple of hours but you do get more charge, I find easiest is simply charge overnight every 7-10 days or when bar drops to 2 or less...

[Pinecone]

Although, if the circuitry is reasonably good, the unit will shut off BEFORE you reach the minimum voltage for a lipo.

[delphin]

Originally Posted by elcreative

Definitely not... full discharge starts to cause internal crystals to form which initially reduce capacity and eventually destroy the cell(s)... this is not anecdotal information, it's from the battery manufacturers... if you leave the unit unused then it's also recommended to turn it off fully with a half charge...

Yes, but like virtually ALL modern products with Lithium batteries, the PRS series readers are designed to make sure that 'full discharge' will NOT happen. Even when the battery gage hits zero bars remaining there is some reserve capacity, and at that point the unit will force a shutdown to protect the battery.

Having said this, I agree 100% that for best cycle-life, it's probably a good idea to charge when your battery gage is down to about half.

I thought I did notice a small improvement after a few charge discharge cycles but I think that this had more to do with usage patterns changing as you become more comfortable with the device and stop playing with features and settle down to mainly using it to read as intended.

I wouldn't worry about intentionally running the battery down to complete shutdown to calibrate the battery pack, because the Sony Readers have only a simple 4 segment readout battery gage icon, that doesn't show a detailed 'time remaining' readout like some other devices.

Also, you will probably eventually run it down to shutoff by accident sooner or later, and although I wouldn't make a habit of this, doing it once or twice (or even a dozen times) isn't going to hurt anything, because the PRS circuits are designed to force a full power down before you reach a discharge level that would hurt the battery.

So, bottom line, try to get the unit on the charger when it hits about the half way point if you can manage it, but no need to be paranoid about it. (For example, I wouldn't stop reading a good book on the train, just because the battery hits the half way point)

[Fortissimo]

Thanks pinecone, delphin & elcreative. Please assess this;

After my initial charge(when I first got the unit), I used it for 3 days and approximately 350 page turns until it dropped one bar from the battery. In the three days, it has either been on stand-by, or on and was only shut down at night when going to bed.
Using simple proportion, it seems the battery will last about 350 X 4 page turns till the battery gives out. This is not bad, but is nowhere near the advertised number and considering the battery is expected to decline with time, it becomes a bit worrisome.

Thanks.

[delphin]

Originally Posted by Fortissimo

Thanks pinecone, delphin & elcreative. Please assess this . . .

Thanks.

Those ratings of thousands of page turns are highly theoretical, and are based on someone just standing there repetitively turning pages as fast as possible.

At one page turn a second, you could in theory do about 3600 page turns in an hour, and though I haven't tried this, I don't doubt that you could get several thousand page turns on one charge under these conditions.

But when you are actually using the reader, then the math gets a little more complicated.


For example, if you did the exact opposite of the above, and changed pages as slowly as possible (without the reader actually timing out and going into sleep mode), then it might surprise you, but I would be very surprised if the reader can run more than about 40 hours straight.

Even at a very leisurely rate, with these very slow page changes, you should still be able to finish your book given 40 hours.

If you read quickly (let's say a page change every 30 seconds), then things would be even be worse, and you might only get 20 or 30 hours of actual reading, but this would be more than enough time to finish a book or two because of the faster reading rate.

So, this isn't as bad as it sounds.

Using the sleep feature instead of completely shutting down the reader also causes an additional battery drain.

From my experience so far with my PRS-650, I would estimate that just being in sleep standby mode, draws enough power to run the battery down completely in about 7 to 10 days.

This is because the SDRAM memory chips in the PRS-650 are active while it is in standby and need to be refreshed even though the CPU is sleeping. If Sony had used fully static CMOS memory, then the standby power would be almost negligible, but a quarter GIG of CMOS would be much more expensive, so like everyone else, Sony uses SDRAM.

By keeping the memory active, the PRS-650 can wake up from sleep almost instantly, but the downside is that you have this constant draw on the battery, so you are looking at about a week and a half battery life EVEN IF YOU DO ALMOST NO READING.

So you pick it; The battery life is . . .

Thousands of page turns in a couple hours -

-or-

Twenty to Forty Hours of constant reading -

-or-

Seven to Ten Days in sleep mode standby (even with little or no reading) -

-or-

Weeks and weeks of intermittent use (if completely powered off when idle) -

-or-

Several Months when powered off and unused -


Obviously, in ACTUAL USE you will have mix of the above situations, and your battery life will vary accordingly.

In actual practice, if I shut down the reader completely when not in use, and try to read straight through without too many distractions (which would cause me to set down the PRS-650 without shutting it down) then I can easily read two, or possibly even three, full length novels on a single charge, over two or three weeks of intermittent reading time.

As a practical matter, I often don't bother to shut down the reader overnight (just letting it go into sleep/stanby mode), and this cuts down the battery life somewhat, so I'm happy if I can read one full length novel over the course of 5 to 7 days.

[Poppaea]

About a 1000 ppages and two weeks reading, reader in constant stand-by. Thats it. For all of us. If you want it to last longer you have to turn it down completely over night, gives you about a week more between charges.

[Fortissimo]

Thanks a lot people. If you'll excuse me,

[Latinandgreek]

Originally Posted by Fortissimo

Thanks a lot people. If you'll excuse me,

You are excused

[Poppaea]

Originally Posted by Fortissimo

Thanks a lot people. If you'll excuse me,

Originally Posted by Latinandgreek

You are excused

See, Latin, see! He is turning his pages with a swipe!!! Good he bought a Sony. You will be able to do the same in a couple of days!!