PRS-350 PRS350 Battery life, real world...

[zmix]

Bought my PRS350 brand new, it had no charge on the battery, so I fully charged it, and for the first charge it lasted nearly 2 weeks, as advertised.

At the end of 2 weeks fully recharged the dead battery.

One week later, dead battery... one week!

What sort of battery life are you experiencing?

[jgray]

It has been discussed here before, but you should never completely discharge a Lithium battery. This type of battery works best when only partially discharged before being fully recharged. This is also true of lead/acid batteries.

You may have shortened the life of your battery by discharging it too much. Try a few full recharge and partial discharge cycles to see if things improve.

It's hard to tell exactly what the remaining capacity is, just from the battery icon on the Sony. However, when it shows only one bar left, I would recharge it as soon as it is convenient. If you run the battery flat, until the reader turns off, you're shooting yourself in the wallet.

I know everyone likes to have bragging rights about how long the battery lasts on these readers, but is it really that much of an inconvenience to plug the thing in once a week?

Joe

[rkomar]

Originally Posted by zmix

Bought my PRS350 brand new, it had no charge on the battery, so I fully charged it, and for the first charge it lasted nearly 2 weeks, as advertised.

At the end of 2 weeks fully recharged the dead battery.

One week later, dead battery... one week!

What sort of battery life are you experiencing?

Two charge cycles probably aren't enough to go on. Google "lithium polymer conditioning". Also, adding lots of books chews up the charge. Give it more time.

[jgray]

I'll have to disagree on the need for "conditioning" of any Lithium batteries. In fact, when I did Google as you suggested, I only found hits that quoted non-authoritative sources.

There are many manufacturer sources that describe the best way to use a Lithium battery. Most are in techno-speak. Here is one from Apple that is in plain English: http://www.apple.com/batteries/. In particular, read the section titled "Standard Charging" and the explanation of a charge cycle.

I don't want to start an argument over this, so I'll just say that however anyone charges their batteries is their own affair. I will continue to charge mine according to what is recommended by those who manufacture them. I've been doing this for years and getting very long life out of my batteries (of course, this is only my experience).

Joe

[Xanthe]

I think what size font you use will make a difference. The larger the font, the more screen pages/refreshes needed just to show a single "paper" page of text. Someone who is using the smallest font size isn't going to have to refresh the page as frequently, so less battery usage.

[rkomar]

Originally Posted by jgray

I'll have to disagree on the need for "conditioning" of any Lithium batteries. In fact, when I did Google as you suggested, I only found hits that quoted non-authoritative sources.

Joe

I assume you were writing in response to me, since no one else brought up Google. In retrospect, my response was likely too terse, as I wasn't suggesting that anyone condition their Li-ion batteries. I suggested the original poster google it, however, to find out that conditioning such batteries is a bad idea (as pretty much every authoritative and non-authoritative web site points out).

Sorry if I gave the wrong impression, and thanks for pointing it out. Let me try again: DO NOT RUN FULL CHARGE/DISCHARGE CYCLES LIKE USED TO BE DONE FOR NI-CD BATTERIES!

[jgray]

Originally Posted by rkomar

I assume you were writing in response to me, since no one else brought up Google.

Yes, you are the guilty party

I'm glad you weren't advocating deep discharging Lithiums. When you mentioned few discharge cycles and then conditioning, I did assume that was what you meant.

When I did a quick Google on the terms you provided, just about everything that I looked at was some non-authoritative source recommending at least some amount of deep discharge for Lithiums.

The only authoritative sources that I find that cautiously recommend such a procedure are specifically targetted at battery packs with built in charge indicator circuitry that may need periodic "calibration" if the battery is often shallowly discharged.

From what I know of the batteries used in these readers, coupled with the fact that users are very unlikely to repeatedly shallow discharge the battery, I doubt that any such "calibration" is needed.

As we both agree on, deep discharging Lithiums is a bad idea.

Joe

[jgray]

While we're discussing batteries, I suggest that everyone read that brief piece from Apple that I linked to. Note that it says that a Lithium is fast charged to only 80% before switching to a trickle charge to reach 100%. This is generally true of all Lithiums. I'm not sure about the Sony readers, but it is common practice to extinguish the charging LED at this 80% point.

What this means is that unless you are in a hurry to finish reading some novel, leave your reader plugged in for a while after the charging LED goes out. This will ensure that you are charging the battery fully. Since most of us do need to sleep about eight hours each day, I'd suggest leaving the reader on charge overnight (or whenever you sleep).

Joe

[zmix]

@jgray: It would require an extended storage period with an uncharged battery for a modern Li-Ion battery to enter a 'deep discharge state'. All modern batteries have a built in computerized charge management system, it's why they are so expensive. Charging the PRS350 initially (from the DEAD state which it was shipped) and then recharging it once after two weeks is not atypical. The Apple battery charging guide is an excellent resource for learning how to get the longest life from your battery. I have followed their suggestions for years on this and certainly do understand the physics behind it. I was simply commenting here because I was surprised that the battery life was half the advertized after only a few cycles.

@rkomar: certainly it's premature to declare that the battery has issues, which is why I started this thread: To see how other PRS350 owners were faring. I'd also like to know if the PRS650 is any better... so far no actual users have replied.


@Xanthe: Many devices like the Sony and the Kindle state the battery life in terms of page turns. I do use the smallest font, always. I average about 400 words per page. My girlfriend uses her Kindle in the opposite way, averaging about 140 words per page, it has a much larger battery too.

[bmatt]

I have a PRS-650, had it for about a month now, and I did the inital full charge. I read about an hour a day usually, at least. I probably top it off once a week or so, but usually I only lose about 1 bar, sometimes 2 bars, during that time. I wait until I have at least one bar down and usually a while after it has lost a bar before I recharge. So I'd say 2 weeks or so is a reasonable estimate, though I'm obviously not a heavy user. I try to charge before it loses the third bar, which I would assume would be about 25% battery capacity. From what I've read you don't want the battery to be constantly at full capacity and obviously most documents state deep charge cycles are not ideal for these batteries, so I figured between 25-50% is a decent point to charge at.

[rkomar]

Originally Posted by zmix

@rkomar: certainly it's premature to declare that the battery has issues, which is why I started this thread: To see how other PRS350 owners were faring. I'd also like to know if the PRS650 is any better... so far no actual users have replied.

I can't help you with either newer model, but I can say that my 2 year old PRS-505 still lasts about 2 weeks if I let it sit, but can drain in one day if I pop the SD card in and out many times and make it re-index the hundreds of books over and over. Indexing can use a lot of power, and could easily have dropped your time to one week if you were adding books to your device in that time.

On a similar note, when I first got my reader, I tried listening to music just to see if it worked (it did), then unplugged the headphones and put the reader to sleep. I got a bit panicky when my reader died within a few hours of operation the next day. It turned out that the music was still continuously playing and draining the battery. I couldn't figure out how to make it stop, so I deleted the songs from the device :P. Battery life was back to normal after that.

So, it's easy to discharge a perfectly good battery within a week.

[MasterGame]

I don't disagree with any of the comments about not needing to fully discharge lithium batteries prior to charging. However, lithium batteries do have a brief break-in period of 2 or 3 charge cycles (discharge about halfway then recharge) before they behave up to their full capacity. Also, occasional discharge to near empty (NOT necessarily total drain) helps the battery level meter (fuel gauge) calibrate to the actual voltages being output by the battery, making for a more accurate meter.

[SeaBookGuy]

My 650 arrived fully charged. I've charged it once (3 bars remaining), as I was going to be traveling without my netbook, and didn't want to get stuck.
I'm really grateful for this thread as I'd been laboring under the memory effect misunderstanding for a long time, worried about re-charging "too soon"!

[MaxLV]

Originally Posted by zmix

@jgray: It would require an extended storage period with an uncharged battery for a modern Li-Ion battery to enter a 'deep discharge state'. All modern batteries have a built in computerized charge management system, it's why they are so expensive. Charging the PRS350 initially (from the DEAD state which it was shipped) and then recharging it once after two weeks is not atypical. The Apple battery charging guide is an excellent resource for learning how to get the longest life from your battery. I have followed their suggestions for years on this and certainly do understand the physics behind it. I was simply commenting here because I was surprised that the battery life was half the advertized after only a few cycles.

@rkomar: certainly it's premature to declare that the battery has issues, which is why I started this thread: To see how other PRS350 owners were faring. I'd also like to know if the PRS650 is any better... so far no actual users have replied.


@Xanthe: Many devices like the Sony and the Kindle state the battery life in terms of page turns. I do use the smallest font, always. I average about 400 words per page. My girlfriend uses her Kindle in the opposite way, averaging about 140 words per page, it has a much larger battery too.

Ibought my 650 in mid september.
I have recharged it twice, mainly to test the third party charger I bought two days ago and to see how long it took to recharge from a USB port on my computer.

Both times the battery was still 75% full according to the battery meter.

I have found that the battery seems to discharge quicker if I let the reader go into standby mode rather than power it off when not using it.

But I haven't come anywhere near fully discharging it.

I use (read) it 3-5 hours a day since buying it, have 300+ books loaded on a 4GB SD card, and have the font set at the default size.

HTH

[grooks]

Originally Posted by MaxLV

I have found that the battery seems to discharge quicker if I let the reader go into standby mode rather than power it off when not using it.

I performed a test on my original 600 and found that shutting it down at night resulting in longer battery between charges versus putting into stand-by mode every time.