Quote:
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
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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.