PRS-650 Concern about charging the battery via USB

[BMaloney]

Please see next post...

[BMaloney]

I didn't buy the cell phone. Did I just save my own life?

Seriously: do you think using a plug from another kind of device could cause that kind of overheating?

I'm on six days and counting. The battery indicator still hasn't gone down! I'm going to start listening to music too; see if that uses up some juice...

[elcreative]

If it's a USB PSU for a USB device then it'll work... USB = 5V and that's what's important, the current taken is appropriate to device ie if it needs 1A and PSU gives 2A, it'll only take 1Abut if it needs 5V and you give it 10V then frying time.

And the examples quoted were extremes and usually involved faulty batteries/devices in the first place... think how many mobile phones, iPods, mobile computers etc are out there... had you ever heard of this happening before this thread, if it was common then the media would be front-paging and jumping up and down on it all the time...

[leighisme]

Does that mean an Apple (iPhone) plug will work? I just bought a 350 and I'd like to avoid buying another charger.

[elcreative]

Probably not, Apple chargers and system were established prior to the now universal standard... almost any other one should work, in particular mobile phone chargers that use micro-USB... see also other threads relating to PSUs...

[Pinecone]

It all depends on the output of the charger and the internal charging circuitry of the Sony reader.

Most cell phones these days use the same battery type of the readers do. They are nominally 3.7 volts, but fully charged at 4.2 volts. Fully discharged is 3.0 volt. Preferably you don't want to fully discahrge or fully charge them. Many cell phones charge to 70 - 80% to increase the cycle life (number of charges) that battery can handle.

Since they all use the same battery, and USB is speced to put out 5 volts, that is sort of the standard these days.

But I really like the iGo system, each tip sets the proper voltage and polarity for the devices.

[elcreative]

Somewhat right, somewhat wrong...applies to non-micro-usb connectors but the current generation of mobiles are predominantly using micro-usb which is 5V... USB = 5V whether micro, mini A or B... USB is 5V

Originally Posted by Pinecone

It all depends on the output of the charger and the internal charging circuitry of the Sony reader.

Most cell phones these days use the same battery type of the readers do. They are nominally 3.7 volts, but fully charged at 4.2 volts. Fully discharged is 3.0 volt. Preferably you don't want to fully discahrge or fully charge them. Many cell phones charge to 70 - 80% to increase the cycle life (number of charges) that battery can handle.

Since they all use the same battery, and USB is speced to put out 5 volts, that is sort of the standard these days.

But I really like the iGo system, each tip sets the proper voltage and polarity for the devices.

[delphin]

Originally Posted by elcreative

Somewhat right, somewhat wrong...applies to non-micro-usb connectors but the current generation of mobiles are predominantly using micro-usb which is 5V... USB = 5V whether micro, mini A or B... USB is 5V

A few minor points -

Any of the newer so-called 'universal' micro USB type chargers should work just fine with all the newer PRS Sony readers. These chargers are designed to meet a new European and Chinese spec that requires them to signal the presence of an external USB charger device by placing a simple short circuit (50 ohms or less) between the USB data lines to signal that an external charger is hooked up.

As already noted, some older Apple USB chargers use an alternate circuit with a voltage divider network to tell the connected device that a charger is hooked up and, because they do not meet the 'data pins shorted' requirements of the newer USB charger spec, THEY WILL NOT WORK.

I bought a USB charger set with both an AC and a DC Car charger from 'Gizmo-Dorks' on Amazon for only a couple bucks, and both worked perfectly.

As far as the best strategy for dealing with the lithium cell battery in your Sony reader, by all means DO feel free to keep them topped-off.

Lithium cells are the opposite of the older NiCad or NiMH cells in this regard. For Lithium cells, repeated deep discharge will actually SHORTEN your batteries useful life.

Excessively deep discharge can destroy a lithium cell in a single charge discharge cycle, so lithium cell powered devices are designed with an unconditional 'hard shutdown' protective circuit that keeps the battery pack safe.

In this regard Lithium batteries are similar to the old style Lead Acid batteries used to start your car. Keep them properly charged and they last YEARS, but let them go completely dead even one time and they can be completely destroyed.

Though it's true that ALL types of batteries will vent or heat up if overcharged, Lithium cells are more of an issue in this regard because lithium can be explosively unstable if the battery does let go. For this reason, modern lithium cell charge controllers are designed to be failsafe against the possibility of an overcharge situation.

Apple, one of the first to jump into Lithium battery technology, also has had several highly publicized safety recalls. You still occasionally hear about a major manufacture dropping the ball and being forced to recall one of their phones or notebooks, but it's getting pretty rare.

In any case, a healthy lithium cell is just going to be intrinsically safer than a sick one, and the best way to keep them healthy is to avoid deep discharge when possible.

I usually recharge my devices at no less than the 50% mark, and have some L-Ion battery packs going on 10 years.

Once every several months, you might want to let the battery drop down to the auto-cuttoff level, just so the device can recalibrate the battery gage, but aside from that, I would aways try to get the device back on charge before you hit that last bar.

[elcreative]

Nice analysis and summation of all the points some of us keep reiterating... here's hoping it's not necessary again... but I doubt it...

[Pinecone]

It is not only the lithium, but the lithium polymer cells used in cell phones and readers also contain a bit of a flammable solvent.

So the combination can make for an impressive condition.

But yes, lithium cells are very senstive to over discharge.

[delphin]

Originally Posted by elcreative

Nice analysis and summation of all the points some of us keep reiterating... here's hoping it's not necessary again... but I doubt it...

Sorry if my summary rehashed, but I thought it would be beneficial to summarize the most salient points.

As a final note, for those of you who have reported that finding a charger was not an issue for you, because you were able to just use one of your old cell phone chargers - good for you, because that was the whole point of trying to standardize these chargers in the first place.

The idea was supposed to be that, with new generations of electronic devices coming out every few months, at least the chargers could be recycled and reused, lessening the amount of disposable e-waste that gets trashed every few months.

In America this standard does not seem to have taken hold yet, so my cell phone charger could NOT be used.

Amazon recognizes this and ships a tiny AC plug to USB charge adapter with their Kindle to U.S. customers, but Sony has never been generous with accessory items that they could charge for anyway, and with this wonderful eco-excuse handy, they decided to opt for maximizing their profits as usual.

After all, you have to hook the reader up to the PC periodically to transfer books anyway, right? - and, in a pinch, the PC will work just fine as a charger, right?

Unfortunately, also thanks to eco-friendly design features, PCs have this nasty habit of going to sleep and SHUTTING DOWN THE USB PORTS to save power after as little as 20 minutes, which I am sure has created a ton of "This stupid thing won't hold a charge" problems and a lot of product returns on the PRS-650 for Sony.

Indeed, there are at least THREE things that can create these kinds of "Doesn't stay charged" problems.

1. As already noted, some older USB chargers will not charge the PRS-650.

2. When charged from the PC, the PRS-650 may receive only a partial charge if the PC's power save features shut down the USB ports before charging is complete.

3. MP3 playback drops the battery life from weeks to hours, and the PRS-650 stupidly does not have a smart 'jack sense' switch to detect that headphones are not actually plugged into the device. So, if the user doesn't notice that it has been accedentally turned on by seeing the musical note Icon at the bottom of the screen, then the battery life will drop to less than a single day.


All of these things taken together seem to have conspired to give the new Sony PRS-350/650 readers a bit of a reputation for battery/charger issues.

Sony could have very easily avoided all these issues by suppling a proper charger and designing the unit so that it would automatically disable MP3 playback when no headphones are plugged into the device, but they didn't, so the best we can do is . . .

1. Get an inexpensive charger that IS PRS-650 compatible (less than $10 on Amazon)

2. If charging from a PC, make sure that the PC's sleep or automatic power saving settings are either disabled completely or set to at least 3 hours to give the PRS-650 time to fully charge (some PC's may keep the ports active while sleeping, so this may, or may not, be an issue).

3. Watch for the little 'musical note' icon next to the battery charge indicator at the bottom of the PRS-650 screen, and make sure that background MP3 audio playback is actually OFF when not wanted. As an additional precaution, you might want to ALSO make sure that you leave the REPEAT feature OFF, and that a long album or audio book is NOT selected for playback. This will give additional protection, just in case the "Resume Playback" function should be activated by something brushing the touch screen (kind of rare, but I have had it happen once). If you leave the player set to the short demo track for example, with the 'repeat' feature off, then even in the worst case that something does accentually 'Resume Playback' then the background audio will only run a few minutes till it reaches the end of that track. On the other hand, if you leave a long multi-track audio book selected, or have any of the music repeat modes turned on, there will be nothing to stop the unintended audio playback, and you can expect the battery to drain quite quickly.

Again, sorry if it seems like this subject has been beat to death, but the whole point is, that with just a little attention to these minor issues, nearly all of the reported problems that folks have been having in getting their PRS-650 to charge, and keeping it charged, should go away.

[Pinecone]

There have been reports of readers left hoooked to powered down USB ports actually discharging.

But some motherboards (a recent build with a Gigabyte in my case) have a utility to keep the USB ports powered on when the computer goes to sleep.

And one thing, all the gloom and doom about what can go wrong with lithium cells, realize that in these devices the cahrging circuits are designed to do the righ tthing, and unless the designer screwed up, they will work well for MANY charge cycles.